PGO Bug Rider BR-250 Service Manual
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PGO Bug Rider BR-250 Service Manual

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BR-250 / BR-250SS / M2-250
SERVICE MANUAL
Manufactured by PGO
of Motive Power Industry Co., Ltd

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Do you have a question about the Bug Rider BR-250 and is the answer not in the manual?

Questions and answers

Yiannis
April 19, 2025

My pgo buggy 200 dosnt start at all but sometimes start without problem the battery is new

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1 comments:
Mr. Anderson
May 10, 2025

Possible reasons for a PGO Bug Rider BR-250 not starting consistently despite having a new battery include:

1. Worn or damaged cylinder, piston, or piston rings.
2. Excessive carbon build-up in the combustion chamber or on the piston head.
3. Incorrectly installed piston.
4. Worn piston pin hole or piston pin.
5. Damaged or clogged carburetor parts such as jets, valves, or gaskets.
6. Worn or damaged starter driven gear, idle gear, or shaft.
7. Faulty starter one-way clutch components (rollers, plungers, springs).
8. Dirty or damaged cam chain guide or cylinder gasket.

These issues can affect compression, fuel delivery, or mechanical operation, preventing consistent starting.

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Summary of Contents for PGO Bug Rider BR-250

  • Page 1 BR-250 / BR-250SS / M2-250 SERVICE MANUAL Manufactured by PGO of Motive Power Industry Co., Ltd...

  • Page 2: Table Of Contents

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ INSPECTION/ADJUSTMENT __________________________________________________________________________________ SERVICE INFORMATION ------------------------------------------------- 1- 1 MAINTENANCE SCHEDULE---------------------------------------------- 1- 2 FUEL LINE/FUEL FILTER-------------------------------------------------- 1- 3 THROTTLE OPERATION -------------------------------------------------- 1- 3 ENGINE OIL-------------------------------------------------------------------- 1- 4 AIR CLEANER----------------------------------------------------------------- 1- 5 SPARK PLUG ------------------------------------------------------------------ 1- 5 VALVE CLEARANCE-------------------------------------------------------- 1- 6 CARBURETOR IDLE SPEED---------------------------------------------- 1- 6...

  • Page 3: Inspection/Adjustment

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT SERVICE INFORMATION GENERAL ！ WARNING •Before running the engine, make sure that the working area is well ventilated. Never run the engine in a closed area. The exhaust contains poisonous carbon monoxide gas, which may cause death to people. •Gasoline is extremely flammable and is explosive under some conditions.

  • Page 4: Maintenance Schedule

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT MAINTENANCE SCHEDULE Perform the periodic maintenance at each scheduled maintenance period. I: Inspect, and Clean, Adjust, Lubricate or Replace if necessary. A: Adjust C: Clean R: Replace T: Tighten Regular Service Mileage (km) Whichever Frequency comes...

  • Page 5: Fuel Line/Fuel Filter

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT FUEL LINE/FUEL FILTER Remove the center cover. Check the fuel lines and replace any parts, which show signs of deterioration, damage or leakage. Check for dirty or clogged fuel filter and replace with a new one if it is clogged. ＊...

  • Page 6: Air Cleaner

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT OIL LEVEL INSPECTION Stop the engine and support the motorcycle upright on level ground. Wait for 2∼3 minutes and check the oil level with the dipstick. Do not screw in the dipstick when making this check. OIL CHANGE ＊...

  • Page 7: Spark Plug

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT Remove the air cleaner element. Air Cleaner Element Check the element and replace it if it is excessively dirty or damaged. CHANGE INTERVAL More frequent replacement is required when riding in unusually dusty or rainy areas. ＊...

  • Page 8: Carburetor Idle Speed

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT Remove the cylinder head cover. Turn the A.C. generator flywheel to the top dead center (TDC) on the compression stroke so that the “T” mark on the flywheel aligns with the index mark on the left crankcase cover. Top Dead Center Inspect and adjust valve clearance.
  • Page 9 BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT Remove the spark plug. Insert a compression gauge. Open the throttle valves fully and pushes the starter button to test the compression. Compression: 16.5±2kg/cm² If the compression is low, check for the following: •Leaky valves •Valve clearance to small Compression Gauge...

  • Page 10: Final Reduction Gear Oil

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT FINAL REDUCTION GEAR OIL ＊ • Place the motorcycle on its main stand on level ground. Stop the engine and remove the oil checks bolt. The oil level shall be at the oil check blowhole. If the oil level is low, add the recommended oil SAE90# to the proper level.

  • Page 11: Clutch Shoe Wear

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT Turn on the headlight switch. Adjust the headlight aim by turning the headlight aim adjusting bolt. CLUTCH SHOE WEAR Start the engine and check the clutch operation by increasing the engine speed gradually. If the motorcycle tends to creep or the engine stalls, check the clutch shoes for wear and replace if necessary.

  • Page 12: Brake System

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT Start the engine and check if there are no bubbles in the coolant and the coolant level is stable. Reinstall the radiator cap. If there are bubbles in the coolant, bleed air from the system.

  • Page 13: Wheels/Tires

    BR & M2 250 ENGINE . INSPECTION/ADJUSTMENT Tighten them to their specified torque values if any looseness is found. WHEELS/TIRES Check the tires for cuts, imbedded nails or other damages. Check the tire pressure. ＊ • Tire pressure should be checked when tires are cold.
  • Page 14 BR 250 ENGINE . INSPECTION/ADJUSTMENT __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ INSPECTION/ADJUSTMENT __________________________________________________________________________________ SERVICE INFORMATION ------------------------------------------------- 2- 1 MAINTENANCE SCHEDULE---------------------------------------------- 2- 2 FUEL LINE/FUEL FILTER-------------------------------------------------- 2- 3 THROTTLE OPERATION -------------------------------------------------- 2- 3 ENGINE OIL-------------------------------------------------------------------- 2- 4 AIR CLEANER----------------------------------------------------------------- 2- 5 SPARK PLUG ------------------------------------------------------------------ 2- 5 VALVE CLEARANCE-------------------------------------------------------- 2- 6 CARBURETOR IDLE SPEED---------------------------------------------- 2- 6 CYLINDER COMPRESSION----------------------------------------------- 2- 7...

  • Page 15: Inspection/Adjustment

    BR 250 ENGINE . INSPECTION/ADJUSTMENT SERVICE INFORMATION GENERAL ！ WARNING •Before running the engine, make sure that the working area is well ventilated. Never run the engine in a closed area. The exhaust contains poisonous carbon monoxide gas, which may cause death to people. •Gasoline is extremely flammable and is explosive under some conditions.

  • Page 16: Maintenance Schedule

    BR 250 ENGINE . INSPECTION/ADJUSTMENT MAINTENANCE SCHEDULE Perform the periodic maintenance at each scheduled maintenance period. I: Inspect, and Clean, Adjust, Lubricate or Replace if necessary. A: Adjust C: Clean R: Replace T: Tighten Regular Service Mileage (km) Whichever Frequency comes first ð...

  • Page 17: Fuel Line/Fuel Filter

    BR 250 ENGINE . INSPECTION/ADJUSTMENT FUEL LINE/FUEL FILTER Remove the center cover. Check the fuel lines and replace any parts, which show signs of deterioration, damage or leakage. Check for dirty or clogged fuel filter and replace with a new one if it is clogged. ＊...

  • Page 18: Air Cleaner

    BR 250 ENGINE . INSPECTION/ADJUSTMENT OIL LEVEL INSPECTION Stop the engine and support the motorcycle upright on level ground. Wait for 2∼3 minutes and check the oil level with the dipstick. Do not screw in the dipstick when making this check. OIL CHANGE ＊...

  • Page 19: Spark Plug

    BR 250 ENGINE . INSPECTION/ADJUSTMENT Remove the air cleaner element. Check the element and replace it if it is excessively dirty or damaged. CHANGE INTERVAL More frequent replacement is required when riding in unusually dusty or rainy areas. ＊ • The air cleaner element has a viscous type paper element.

  • Page 20: Carburetor Idle Speed

    BR 250 ENGINE . INSPECTION/ADJUSTMENT Remove the cylinder head cover. Turn the A.C. generator flywheel to the top dead center (TDC) on the compression stroke so that the “T” mark on the flywheel aligns with the index mark on the left crankcase cover. Top Dead Center Inspect and adjust valve clearance.
  • Page 21 BR 250 ENGINE . INSPECTION/ADJUSTMENT Remove the spark plug. Insert a compression gauge. Open the throttle valves fully and pushes the starter button to test the compression. Compression: 16.5±2kg/cm² If the compression is low, check for the following: •Leaky valves •Valve clearance to small Compression Gauge •Leaking cylinder head gasket...

  • Page 22: Final Reduction Gear Oil

    BR 250 ENGINE . INSPECTION/ADJUSTMENT FINAL REDUCTION GEAR OIL ＊ • Place the motorcycle on its main stand on level ground. Stop the engine and remove the oil checks bolt. The oil level shall be at the oil check blowhole. If the oil level is low, add the recommended oil SAE90# to the proper level.

  • Page 23: Clutch Shoe Wear

    BR 250 ENGINE . INSPECTION/ADJUSTMENT Turn on the headlight switch. Adjust the headlight aim by turning the headlight aim adjusting bolt. CLUTCH SHOE WEAR Start the engine and check the clutch operation by increasing the engine speed gradually. If the motorcycle tends to creep or the engine stalls, check the clutch shoes for wear and replace if necessary.

  • Page 24: Brake System

    BR 250 ENGINE . INSPECTION/ADJUSTMENT Start the engine and check if there are no bubbles in the coolant and the coolant level is stable. Reinstall the radiator cap. If there are bubbles in the coolant, bleed air from the system. Fill the reserve tank with the recommended coolant up to the upper line.

  • Page 25: Wheels/Tires

    BR 250 ENGINE . INSPECTION/ADJUSTMENT WHEELS/TIRES Check the tires for cuts, imbedded nails or other damages. Check the tire pressure. ＊ • Tire pressure should be checked when tires are cold. Tire Pressure Off road On road Front 0.3kg/cm² 0.5kg/cm² Rear 0.3kg/cm²...
  • Page 26 BR & M2 250 ENGINE . LUBRICATION SYSTEM __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ LUBRICATION SYSTEM __________________________________________________________________________________ LUBRICATION SYSTEM DIAGRAM ----------------------------------- 3-1 SERVICE INFORMATION ------------------------------------------------- 3-2 TROUBLESHOOTING------------------------------------------------------- 3-2 ENGINE OIL/OIL FILTER -------------------------------------------------- 3-3 OIL PUMP REMOVAL------------------------------------------------------- 3-4 OIL PUMP DISASSEMBLY ------------------------------------------------ 3-4 OIL PUMP INSPECTION --------------------------------------------------- 3-5 OIL PUMP ASSEMBLY ----------------------------------------------------- 3-5 OIL PUMP INSTALLATION ----------------------------------------------- 3-6...
  • Page 27 BR & M2 250 ENGINE . LUBRICATION SYSTEM LUBRICATION SYSTEM Rocker Arm Shaft Crankshaft Oil Filter Screen Oil Pump...

  • Page 28: Lubrication System Diagram

    BR & M2 250 ENGINE . LUBRICATION SYSTEM SERVICE INFORMATION GENERAL INSTRUCTIONS • The maintenance of lubrication system can be performed with the engine installed in the frame. • Drain the coolant before starting any operations. • Use care when removing and installing the oil pump not to allow dust and foreign matters to enter the engine and oil line.

  • Page 29: Engine Oil/Oil Filter

    BR & M2 250 ENGINE . LUBRICATION SYSTEM ENGINE OIL/OIL FILTER ＊ • Place the motorcycle upright on level ground for engine oil level check. • Run the engine for 2∼3 minutes and check the oil level after the engine is stopped for 2∼3 minutes.

  • Page 30: Oil Pump Removal

    BR & M2 250 ENGINE . LUBRICATION SYSTEM Bolts OIL PUMP REMOVAL First drain the coolant. Remove the right crankcase cover. ( ð 9-3) Remove the A.C. generator starter driven gear. ( ð 9-4) Remove the attaching bolt and oil separator cover.

  • Page 31: Oil Pump Inspection

    BR & M2 250 ENGINE . LUBRICATION SYSTEM OIL PUMP INSPECTION Measure the pump body-to-outer rotor clearance. Service Limit: 0.25mm replace if over Outer Rotor Measure the inner rotor-to-outer rotor clearance. Service Limit: 0.20mm replace if over Inner Rotor Measure the rotor end-to-pump body clearance. Service Limit: 0.12mm replace if over Pump Body Rotor End...

  • Page 32: Oil Pump Installation

    BR & M2 250 ENGINE . LUBRICATION SYSTEM Install the pump cover by aligning the hole in the cover with the dowel pin. Tighten the screw to secure the pump cover. Make sure that the pump shaft rotates freely without binding. Dowel Pin Arrow Mark OIL PUMP INSTALLATION...
  • Page 33 . CYLINDER HEAD/VALVES BR & M2 250 ENGINE __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CYLINDER HEAD/VALVES __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 4- 1 SERVICE INFORMATION ------------------------------------------------- 4- 2 TROUBLESHOOTING------------------------------------------------------- 4- 3 CYLINDER HEAD COVER REMOVAL--------------------------------- 4- 4 CAMSHAFT REMOVAL ---------------------------------------------------- 4- 4 CYLINDER HEAD REMOVAL -------------------------------------------- 4- 6 CYLINDER HEAD DISASSEMBLY -------------------------------------- 4- 7 CYLINDER HEAD ASSEMBLY ------------------------------------------- 4- 8...

  • Page 34: Cylinder Head/Valves

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES SCHEMATIC DRAWING...

  • Page 35: Service Information

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder head can be serviced with the engine installed in the frame. Coolant in the radiator and water jacket must be drained first. • When assembling, apply molybdenum disulfide grease or engine oil to the valve guide movable parts and valve arm sliding surfaces for initial lubrication.

  • Page 36: Troubleshooting

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES TROUBLESHOOTING • The poor cylinder head operation can be diagnosed by a compression test or by tracing engine top-end noises. Poor performance at idle speed White smoke from exhaust muffler • Compression too low •...

  • Page 37: Cylinder Head Cover Removal

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES CYLINDER HEAD COVER REMOVAL Remove the center cover.) Remove the met-in box. Remove the cylinder head cover four bolts and then remove the cylinder head cover. Bolt CAMSHAFT REMOVAL Turn the A.C. generator flywheel so that the “T” mark on the flywheel aligns with the index mark on the crankcase.
  • Page 38 BR & M2 250 ENGINE . CYLINDER HEAD/VALVES Remove the camshaft gear from the cam chain to remove the camshaft. Camshaft Gear CAMSHAFT INSPECTION Check each cam lobe for wear or damage. Measure the cam lobe height. Service Limits: IN: 34.14mm replace if below EX:34.02mm replace if below Camshaft Bearings Check each camshaft bearing for play or damage.

  • Page 39: Cylinder Head Removal

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES Inspect the camshaft holder, valve rocker arms and rocker arm shafts for wear or damage. ＊ If the valve rocker arm contact surface is worn, check each cam lobe for wear or damage.
  • Page 40 BR & M2 250 ENGINE . CYLINDER HEAD/VALVES springs, spring seats and valve stem seals using a valve spring compressor. ＊ • Be sure to compress the valve springs with a valve spring compressor. • Mark all disassembled parts to ensure correct reassembly.

  • Page 41: Cylinder Head Assembly

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES Check the spark plug hole and valve areas for cracks. Check the cylinder head for warpage with a straight edge and feeler gauge. Service Limit: 0.05mm repair or replace if Feeler Gauge over VALVE SPRING FREE LENGTH Measure the free length of the inner and outer...

  • Page 42: Cylinder Head Installation

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES Cylinder Head Gasket CYLINDER HEAD INSTALLATION Install the cam chain guide. Install the dowel pins and a new cylinder head gasket. Cam Chain Guide Dowel Pins Cam Chain Install the cylinder head and take out the cam chain Valve Rocker Arms Assemble the camshaft holder.
  • Page 43 BR & M2 250 ENGINE . CYLINDER HEAD/VALVES on the crankcase. Keep the round hole on the camshaft gear facing up and align the punch marks on the camshaft gear with the cylinder head surface (Position the intake and exhaust cam lobes down.) and install the cam chain over the camshaft gear.

  • Page 44: Cylinder Head Cover Installation

    BR & M2 250 ENGINE . CYLINDER HEAD/VALVES Apply engine oil to a new O-ring and install it. O-ring Tighten the cam chain tension cap screw. CYLINDER HEAD COVER ＊ Be sure to install the gasket into the groove Cylinder Head Cover properly.
  • Page 45 . CYLINDER/PISTON BR & M2 250 ENGINE __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CYLINDER/PISTON __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 5-1 SERVICE INFORMATION ------------------------------------------------- 5-2 TROUBLESHOOTING------------------------------------------------------- 5-2 CYLINDER REMOVAL------------------------------------------------------ 5-3 PISTON REMOVAL---------------------------------------------------------- 5-3 PISTON INSTALLATION--------------------------------------------------- 5-7 CYLINDER INSTALLATION ---------------------------------------------- 5-7...

  • Page 46: Schematic Drawing

    BR & M2 250 ENGINE . CYLINDER/PISTON SCHEMATIC DRAWING...

  • Page 47: Service Information

    BR & M2 250 ENGINE . CYLINDER/PISTON SERVICE INFORMATION GENERAL INSTRUCTIONS • The cylinder and piston can be serviced with the engine installed in the frame. • When installing the cylinder, use a new cylinder gasket and make sure that the dowel pins are correctly installed.

  • Page 48: Cylinder Removal

    BR & M2 250 ENGINE . CYLINDER/PISTON CYLINDER REMOVAL Cylinder Cam Chain Guide Remove the cylinder head. ( ð 4-7) Remove the water hose from the cylinder. Water Hose Remove the cam chain guide. Remove the cylinder. Gasket Remove the cylinder gasket and dowel pins. Clean any gasket material from the cylinder surface.
  • Page 49 BR & M2 250 ENGINE . CYLINDER/PISTON Inspect the piston, piston pin and piston rings. Remove the piston rings. ＊ • Take care not to damage or break the piston rings during removal. Clean carbon deposits from the piston ring grooves.
  • Page 50 BR & M2 250 ENGINE . CYLINDER/PISTON Service Limit: 16.96mm replace if below Measure the piston O.D. ＊ • Take measurement at 9mm from the bottom and 90° to the piston pin hole. Service Limit: 72.60mm replace if below Measure the piston-to-piston pin clearance. Service Limit: 0.02mm replace if over CYLINDER INSPECTION Inspect the cylinder bore for wear or damage.

  • Page 51: Piston Installation

    BR & M2 250 ENGINE . CYLINDER/PISTON Service Limit: 0.05mm repair or replace if over Measure the connecting rod small end I.D. Service Limit: 17.06mm replace if over PISTON RING INSTALLATION Install the piston rings onto the piston. Apply engine oil to each piston ring. ＊...

  • Page 52: Cylinder Installation

    BR & M2 250 ENGINE . CYLINDER/PISTON Remove any gasket material from the crankcase surface. ＊ • Be careful not to drop foreign matters into the crankcase. Piston Install the piston, piston pin and a new piston pin clip. ＊ •...
  • Page 53 BR & M2 250 ENGINE . CYLINDER/PISTON ＊ • Insert the tab on the cam chain guide into the cylinder groove. Dowel Pin Install the cylinder gasket and dowel pins. Connect the water hose to the cylinder. Install the cylinder head. ( ð 4-9) Tighten the cylinder base bolt.
  • Page 54 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ DRIVE AND DRIVEN PULLEYS/ KICK STARTER __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 6- 1 SERVICE INFORMATION ------------------------------------------------- 6- 2 TROUBLESHOOTING------------------------------------------------------- 6- 2 LEFT CRANKCASE COVER ---------------------------------------------- 6- 3 DRIVE PULLEY --------------------------------------------------------------- 6- 4 CLUTCH/DRIVEN PULLEY------------------------------------------------ 6- 8...

  • Page 55: Drive And Driven Pulleys

    . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER SCHEMATIC DRAWING...

  • Page 56: Service Information

    . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER SERVICE INFORMATION GENERAL INSTRUCTIONS • The drive pulley, clutch and driven pulley can be serviced with the engine installed. • Avoid getting grease and oil on the drive belt and pulley faces. Remove any oil or grease from them to minimize the slipping of drive belt and drive pulley.

  • Page 57: Left Crankcase Cover

    . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER LEFT CRANKCASE COVER REMOVAL Loosen the drive belt air tube band screw. Remove the four bolts on the left crankcase surface cover. Cover Bolts Remove the left crankcase cover bolts and left crankcase covers.

  • Page 58: Drive Pulley

    . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER band screw. Tube Band Screw Universal Holder DRIVE PULLEY REMOVAL Remove the left crankcase cover. Hold the drive pulley using an universal holder and remove the drive face nut and washer. Remove the drive pulley face.
  • Page 59 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Movable Drive Face Assembly Ramp Plate DISASSEMBLY Remove the ramp plate. Remove the weight rollers. Weight Roller INSPECTION Check each weight roller for wear or damage. Measure each weight roller O.D. Service Limit: 18.00mm replace if below Drive Pulley Collar Measure the movable drive face bushing...
  • Page 60 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER assembly I.D. Service Limit: 27.13mm replace if over Check the drive pulley collar for wear or damage. Measure the O.D. of the drive pulley collar sliding surface. Service Limit: 26.90mm replace if below ASSEMBLY Install the weight rollers into the movable drive face.
  • Page 61 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Drive Pulley Collar Insert the drive pulley collar into the movable drive face. INSTALLATION Install the movable drive face onto the crankshaft. Movable Drive Face Assembly Driven Pulley Drive Pulley Collar Lay the drive belt on the driven pulley.

  • Page 62: Clutch/Driven Pulley

    . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Drive Face Nut Washer Universal Holder Hold the drive pulley with the universal holder and tighten the drive face nut. Torque: 49.0∼58.5N-m Special Universal Holder ＊ • Do not get oil or grease on the drive belt or drive pulley faces.
  • Page 63 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Service Limit: 2.0mm replace if below Clutch/Driven Pulley CLUTCH/DRIVEN PULLEY DISASSEMBLY Clutch Spring Compressor Hold the clutch/driven pulley assembly with the clutch spring compressor. ＊ • Be sure to use a clutch spring compressor to avoid spring damage.
  • Page 64 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER O-ring Movable Driven Face Remove the oil seal from the movable driven Oil Seal face. INSPECTION Measure the driven face spring free length. Service Limit: 130.5mm replace if below Check the driven face assembly for wear or damage.
  • Page 65 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Service Limit: 40.05mm replace if over DRIVEN PULLEY FACE BEARING REPLACEMENT Check the bearings for play and replace them if they have excessive play. Drive the inner needle bearing out of the driven pulley face.
  • Page 66 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Bearing Driver CLUTCH DISASSEMBLY Remove the circlips and retainer plate to Circlips disassemble the clutch. ＊ • Keep grease off the clutch linings. Retainer Plate Clutch Lining...
  • Page 67 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER CLUTCH ASSEMBLY Circlips Install the damper rubbers on the drive plate pins. Install the clutch weights/shoes and clutch springs onto the drive plate. Install the retainer plate and secure with the circlips.
  • Page 68 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Apply grease to the guide rollers and guide roller pins and then install them into the holes of the driven face. Driven Face Movable Driven Face Seal Collar Install the seal collar.
  • Page 69 . DRIVE AND DRIVEN PULLEYS/ BR & M2 250 ENGINE KICK STARTER Torque: 49.0∼58.8kg-m Special Universal Holder Install the drive belt. ( ð 6-7) Install the left crankcase cover. ( ð 6-3)
  • Page 70 . FINAL REDUCTION BR & M2 250 ENGINE __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ FINAL REDUCTION __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 7-1 SERVICE INFORMATION ------------------------------------------------- 7-2 TROUBLESHOOTING------------------------------------------------------- 7-2 FINAL REDUCTION DISASSEMBLY ----------------------------------- 7-3 FINAL REDUCTION INSPECTION-------------------------------------- 7-3 FINAL REDUCTION ASSEMBLY ---------------------------------------- 7-6...

  • Page 71: Schematic Drawing

    BR & M2 250 ENGINE . FINAL REDUCTION SCHEMATIC DRAWING...

  • Page 72: Service Information

    BR & M2 250 ENGINE . FINAL REDUCTION SERVICE INFORMATION GENERAL INSTRUCTIONS • The servicing operations of this section can be made with the engine installed. • When replacing the drive shaft, use a special tool to hold the bearing inner race for this operation. SPECIFICATIONS Specified Oil: SAE 90# Oil Capacity:...

  • Page 73: Final Reduction Disassembly

    BR & M2 250 ENGINE . FINAL REDUCTION FINAL REDUCTION Bolts DISASSEMBLY Remove the exhaust muffler. Remove the rear brake caliper. Remove the right rear shock absorber. Remove the rear fork. Remove the rear wheel. Remove the left crankcase cover. ( ð 6-3) Remove the clutch/driven pulleys.
  • Page 74 BR & M2 250 ENGINE . FINAL REDUCTION Inspect the final gear and final shaft for wear, damage or seizure. Drive Shaft Bearing Check the left crankcase bearings for excessive play and inspect the oil seal for wear or damage. Countershaft Bearing Final Shaft Bearing Drive Shaft Bearing...
  • Page 75 BR & M2 250 ENGINE . FINAL REDUCTION BEARING REPLACEMENT (TRANSMISSION CASE COVER) Remove the transmission case cover bearings using the bearing remover. Remove the final shaft oil seal. Drive Shaft Bearing Pilot, 15mm Drive new bearings into the transmission case cover.

  • Page 76: Final Reduction Assembly

    BR & M2 250 ENGINE . FINAL REDUCTION Drive new bearings into the left crankcase. Install a new drive shaft oil seal. Pilot FINAL REDUCTION ASSEMBLY Install the drive shaft into the left crankcase. Drive Shaft Install the final gear and final shaft into the left crankcase.
  • Page 77 BR & M2 250 ENGINE . FINAL REDUCTION Install the countershaft and gear into the left crankcase. Install the resin washer onto the counter-shaft. Install the dowel pins and a new gasket. Countershaft Install the transmission case cover. Transmission Case Cover Bolts Install and tighten the transmission case cover bolts.
  • Page 78 BR & M2 250 ENGINE . FINAL REDUCTION specified oil. ＊ • Place the motorcycle on its main stand on level ground. • Check the oil-sealing washer for wear or damage. Specified Gear Oil: SAE90# Oil Capacity: At disassembly : 0.2 liter At change : 0.18 liter Install and tighten the oil check bolt.
  • Page 79 BR & M2 250 ENGINE . CARBURETOR _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ CARBURETOR _________________________________________________________________________________ DIAPHRAGM AND PISTON OPERATION ---------------------------------------------- 8-1 SLOW SYSTEM ----------------------------------------------------------------------- 8-2 COASTING ENRICHMENT SYSTEM --------------------------------------------------- 8-2 MAIN SYSTEM ----------------------------------------------------------------------- 8-4 AUTO-ENRICHENER (AUTO-CHOKE) SYSTEM --------------------------------------- 8-5 FLOAT SYSTEM ---------------------------------------------------------------------- 8-6 ACCELERATOR PUMP SYSTEM ------------------------------------------------------- 8-7...

  • Page 80: Carburetor

    BR & M2 250 ENGINE . CARBURETOR 8-1 DIAPHRAGM AND PISTON OPERATION The carburetor is a variable-venturi type, whose venturi cross sectional area is increased or decreased automatically by the piston valve•. The piston valve moves according to the negative pressure present on the downstream side of the venturi A. Negative pressure is admitted into the diaphragm chamber ‚...

  • Page 81: 8-2 Slow System

    BR & M2 250 ENGINE . CARBURETOR 8-2 SLOW SYSTEM This system supplies fuel during engine operation when the throttle valve • is closed or slightly opened. The fuel from the float chamber ‚ is metered by the pilot jet ƒ where it mixes with air coming in through the pilot air jet „.
  • Page 82 BR & M2 250 ENGINE . CARBURETOR...

  • Page 83: 8-4 Main System

    BR & M2 250 ENGINE . CARBURETOR 8-4 MAIN SYSTEM As the throttle valve • is opened, engine speed rises and negative pressure in the venturi A increases. This causes the piston valve ‚ to move upward. The fuel in the float chamber ƒ...

  • Page 84: 8-5 Auto-Enrichener (Auto-Choke) System

    BR & M2 250 ENGINE . CARBURETOR 8-5 AUTO-ENRICHENER (AUTO-CHOKE) SYSTEM The automatic enrichener (automatic choke) device consists of the PTC heater A, the thermo-wax B and the plunger/needle •. When the thermo-wax B is cold, the plunger/needle • moves upward, Fuel is drawn into the enrichener circuit from the float chamber ‚. Enrichener jet ƒ...

  • Page 85: 8-6 Float System

    BR & M2 250 ENGINE . CARBURETOR 8-6 FLOAT SYSTEM The float • and needle valve ‚ work in conjunction with one another. As the float chamber ƒ, the float • rises and the needle valve ‚ pushes up against the valve seat. When this occurs, no fuel enters the float chamberƒ.

  • Page 86: 8-7 Accelerator Pump System

    BR & M2 250 ENGINE . CARBURETOR 8-7 ACCELERATOR PUMP SYSTEM This system works only when the rider opens throttle grip quickly as pump send the necessary amount of fuel to the carburetor bore for correcting fuel/air mixture ratio. When the rider open the throttle grip quickly, the intaken air volume becomes large and air velocity at the bottom of the throttle valve (piston valve)is slow and sucking volume of fuel is less.

  • Page 87: 8-8 Inspection

    BR & M2 250 ENGINE . CARBURETOR 8-8 INSPECTION Check the following parts for damage and clogging. * Pilot jet * Piston valve * Main jet * Starter jet * Main air jet * Gaskets and O-rings * Pilot air jet No.1 & No.2 * Pilot outlet and bypass * Needle jet holder * Coasting enrichement valve...
  • Page 88 . CARBURETOR BR & M2 250 ENGINE AUTO-ENRICHENER INSPECTION Ÿ Disconnect the lead wire coupler•. Ÿ Remove the cover‚. Ÿ Connect the positive ♁ terminal of a 12V battery to Yellow/white lead and the negative Θ terminal to Black/ White. Ÿ...
  • Page 89 BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH ENGINE __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ A.C. GENERATOR/STARTER CLUTCH __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 9-1 SERVICE INFORMATION ------------------------------------------------- 9-2 TROUBLESHOOTING------------------------------------------------------- 9-2 RIGHT CRANKCASE COVER REMOVAL ---------------------------- 9-3 STATOR REMOVAL--------------------------------------------------------- 9-3 FLYWHEEL REMOVAL----------------------------------------------------- 9-3 STARTER CLUTCH---------------------------------------------------------- 9-4 FLYWHEEL INSTALLATION --------------------------------------------- 9-5 STATOR INSTALLATION ------------------------------------------------- 9-6...

  • Page 90: Generator/Starter Clutch

    BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH SCHEMATIC DRAWING...

  • Page 91: Service Information

    BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH ENGINE SERVICE INFORMATION GENERAL INSTRUCTIONS • All servicing operations and inspections in this section can be made with the engine installed. • Drain the coolant before removing the right crankcase cover. •...

  • Page 92: Stator Removal

    BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH Disconnect the water hoses from the right crankcase cover. Remove the nine bolts attaching the right crankcase cover and the cover. Water Outlet Hose A.C. Generator Stator Screws STATOR REMOVAL Remove the two pulser coil attaching screws and the pulser coil.
  • Page 93 BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH ENGINE Remove the starter driven gear. Starter Driven Gear Remove the starter idle gear and shaft. Starter Idle Gear INSPECTION Inspect the starter driven gear for wear or damage. Measure the starter driven gear I.D. and O.D. Service Limits: I.D.

  • Page 94: Flywheel Installation

    BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH INSTALLATION Install the starter driven gear onto the crankshaft. Starter Idle Gear Shaft Install the starter idle gear and shaft. FLYWHEEL INSTALLATION Install the flywheel onto the crankshaft by aligning Starter Driven Gear the key on the crankshaft with the groove in the Flywheel flywheel.

  • Page 95: Right Crankcase Cover Installation

    BR & M2 250 ENGINE . A.C. GENERATOR/STARTER CLUTCH ENGINE Install the wire grommet in the groove in the right crankcase cover securely. ＊ Be sure to route the stator wire under the pulser coil. Pulser Coil Dowel Pins RIGHT CRANKCASE COVER INSTALLATION Install the two dowel pins and a new gasket.
  • Page 96 BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ CRANKCASE/CRANKSHAFT __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 10-1 SERVICE INFORMATION ------------------------------------------------- 10-2 TROUBLESHOOTING------------------------------------------------------- 10-2 CRANKCASE SEPARATION---------------------------------------------- 10-3 CRANKSHAFT INSPECTION --------------------------------------------- 10-4 CRANKCASE ASSEMBLY ------------------------------------------------- 10-5...

  • Page 97: Schematic Drawing

    BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT SCHEMATIC DRAWING...

  • Page 98: Service Information

    BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT SERVICE INFORMATION GENERAL INSTRUCTIONS • This section covers crankcase separation to service the crankshaft. The engine must be removed for this operation. • When separating the crankcase, never use a driver to pry the crankcase mating surfaces apart forcedly to prevent damaging the mating surfaces.

  • Page 99: Crankcase Separation

    BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT CRANKCASE SEPARATION Remove the cam chain tensioner slipper bolt. Remove the cam chain tensioner slipper and cam chain. Remove the three right crankcase attaching bolts. Bolt Cam Chain Remove the left crankcase. Left Crankcase Right Crankcase Place the crankcase with the left crankcase down and remove the right crankcase from the left...

  • Page 100: Crankshaft Inspection

    BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT Left Crankcase CRANKSHAFT INSPECTION Measure the connecting rod big end side clearance. Service Limit: 0.6mm replace if over Measure the connecting rod small end I.D. Service Limit: 17.06mm replace if over Oil Seal Measure the crankshaft runout.

  • Page 101: Crankcase Assembly

    BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT Measure the crankshaft bearing play. Service Limits: Axial : 0.20mm replace if over Radial : 0.05mm replace if over Play Play CRANKCASE ASSEMBLY Axial Clean off all gasket material from the crankcase Radial mating surfaces.
  • Page 102 BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT Gasket Install the two dowel pins and a new gasket. Dowel Pins Right Crankcase Place the right crankcase over the crankshaft and onto the left crankcase. ＊ • Install the right crankcase squarely and do not tap it with an iron or plastic hammer.
  • Page 103 BR & M2 250 ENGINE . CRANKCASE/CRANKSHAFT Torque: 7.8∼11.8N-m Bolt Cam Chain Tensioner Slipper...
  • Page 104 BR & M2 250 ENGINE . COOLING SYSTEM __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________ COOLING SYSTEM __________________________________________________________________________________ SCHEMATIC DRAWING --------------------------------------------------- 11- 1 SERVICE INFORMATION ------------------------------------------------- 11- 2 TROUBLESHOOTING------------------------------------------------------- 11- 2 COOLING SYSTEM TESTING-------------------------------------------- 11- 4 RADIATOR--------------------------------------------------------------------- 11- 4 WATER PUMP----------------------------------------------------------------- 11-15 THERMOSTAT ---------------------------------------------------------------- 11-16...

  • Page 105: Schematic Drawing

    BR & M2 250 . COOLING SYSTEM ENGINE SCHEMATIC DRAWING...

  • Page 106: Service Information

    BR & M2 250 ENGINE . COOLING SYSTEM SERVICE INFORMATION GENERAL INSTRUCTIONS • The water pump must be serviced after removing the engine. Other cooling system service can be done with the engine installed in the frame. • The engine must be cool before servicing the cooling system. When the coolant temperature is over 100℃, never remove the radiator cap to release the pressure because the boiling coolant may cause danger.

  • Page 107: Cooling System Testing

    BR & M2 250 . COOLING SYSTEM ENGINE Radiator cap relief pressure 0.9±0.15kg/cm² Begins to open 80±2℃ Thermostat temperature Full-open 90℃ Valve lift 3.5∼4.5mm Radiator: 825cc Coolant capacity Total system 1165cc Reserve tank: 340cc COOLANT GRAVITY Temp. ℃ Coolant concentration 1.009 1.009 1.008 1.008 1.007 1.006 1.005 1.003 1.001 0.009 0.997 1.018 1.107 1.017 1.016 1.015 1.014 0.013 1.011 1.009 1.007 1.005 1.028 1.027 1.026 1.025 1.024 1.022 1.020 1.018 1.016 1.014 1.012...

  • Page 108: Radiator

    BR & M2 250 ENGINE . COOLING SYSTEM ＊ Apply water to the cap sealing surface before testing. Radiator Cap Radiator Cap Relief Pressure: 0.9±0.15kg/cm² Install the radiator tester onto the radiator and apply specified pressure to it. It must hold specified pressure for at least six seconds.
  • Page 109 BR & M2 250 . COOLING SYSTEM ENGINE Overflow Tube RADIATOR REMOVAL Drain the coolant. ( ð 3-9) Disconnect the air vent tube from the radiator filler. Remove the overflow tube clamp and disconnect the overflow tube. Air Vent Tube Upper Hose Loosen the hose band and disconnect the upper hose and lower hose from the radiator.
  • Page 110 BR & M2 250 ENGINE . COOLING SYSTEM Thermostatic Switch Wire Radiator Remove the two bolts and two nuts on the radiator. Bolts Nuts Fan/Shroud RADIATOR DISASSEMBLY Remove the four bolts and then remove the fan/shroud from the radiator. Bolts Fan Motor Wire Coupler Thermostatic Switch Check fan motor by battery.
  • Page 111 BR & M2 250 . COOLING SYSTEM ENGINE Fan Motor CHECK THERMOSTATIC SWITCH When coolant temperature lower then 85~90 ℃ the thermostatic switch OFF. When coolant temperature over 85~90℃ the Thermostatic Switch thermostatic switch ON. Install the fan shroud on the radiator with the four bolts.
  • Page 112 BR & M2 250 ENGINE . COOLING SYSTEM Nuts Bolts Upper Hose Connect the upper and lower hoses and secure them with hose bands. Connect the thermostatic switch wire and fan motor wire couplers. Thermostatic Switch Wire Lower Hose Overflow Tube Connect the overflow tube and secure with the tube clamp.

  • Page 113: Water Pump

    BR & M2 250 . COOLING SYSTEM ENGINE Right Crankcase Cover WATER PUMP MECHANICAL SEAL (WATER SEAL) INSPECTION Inspect the telltale hole for signs of mechanical seal coolant leakage. If the mechanical seal is leaking, remove the right crankcase cover and replace the mechanical seal.
  • Page 114 BR & M2 250 ENGINE . COOLING SYSTEM Impeller (Left Hand Threads) Remove the water pump impeller. ＊ The impeller has left hand threads. Mechanical Seal Inspect the mechanical (water) seal and seal washer for wear or damage. ＊ The mechanical seal and seal washer must be replace as a set.
  • Page 115 BR & M2 250 . COOLING SYSTEM ENGINE Water Pump Assembly Inner Bearing Remove the water pump bearing snap ring from the water pump assembly. Remove the water pump shaft and inner bearing. Snap Ring Water Pump Shaft Water Pump Assembly Remove the water pump shaft outer bearing.
  • Page 116 BR & M2 250 ENGINE . COOLING SYSTEM Drive in a new mechanical seal using a mechanical seal driver. ＊ Apply sealant to the right crankcase cover fitting surface of a new mechanical seal and then drive in the mechanical seal. Outer Bearing WATER PUMP SHAFT INSTALLATION...
  • Page 117 BR & M2 250 . COOLING SYSTEM ENGINE Install the dowel pins and a new gasket and then install the water pump assembly to the right crankcase cover. Tighten the eight bolts to secure the right crankcase cover. ＊ When installing the water pump assembly, aligning the groove on the water pump shaft Bolts with the tab on the oil pump shaft.
  • Page 118 BR & M2 250 ENGINE . COOLING SYSTEM Install the two dowel pins and a new gasket. Water Pump Cover Install the water pump cover and tighten the 4 bolts. Torque: 7.8∼11.8N-m Impeller (Left Hand Threads) THERMOSENSOR THERMOSENSOR REMOVAL Remove the seat, met-in box and center cover. Drain the coolant.

  • Page 119: Thermostat

    BR & M2 250 . COOLING SYSTEM ENGINE THERMOSENSOR INSPECTION Thermosensor Suspend the thermosensor in a pan of water over a burner and measure the resistance through the sensor as the water heats up. Temperature(℃) Resistance(Ω) Thermometer Thermosensor Wire THERMOSENSOR INSTALLATION Apply 3-BOND No.
  • Page 120 BR & M2 250 ENGINE . COOLING SYSTEM housing halves. Thermostat Thermostat Remove the thermostat from the thermostat housing. Thermostat Bolt THERMOSTAT INSPECTION Suspend the thermostat in a pan of water over a burner and gradually raise the water temperature to check its operation.
  • Page 121 BR & M2 250 . COOLING SYSTEM ENGINE O-ring THERMOSTAT INSTALLATION The installation sequence is the reverse of removal. ＊ Replace the O-ring with a new one and apply grease to it. Thermostat Housing Fill the cooling system with the specified coolant.

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Bug rider br-250ssBug rider m2-250

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