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Related Manuals for Bridgestone 50 SPORT
Summary of Contents for Bridgestone 50 SPORT
- Page 1 BRIDGESTONE OWNER’S HANDBOOK & SERVICE MANUAL 50 Sport, 60 Sport, 90, 90 Trail, 90 Mountain, 90 Sport, 175 Dual Twin...
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Page 2: Table Of Contents
E. Selenium Rectifier ........50 Sport, 60 Sport and 90cc models ...... -
Page 3: Specifications
SPECIFICATIONS BS 50 Sport BS 60 Sport 'Engine: (1) Type: 2-stroke, Single Cyl. 2-stroke, Single Cyl. (2) Piston Displacement: 50cc.(3.15cu.in.) 58cc.(3.54cu.in.) (3) Bore & Stroke 39 mm x 42 mm (1.53 x 1.65 in.) 42 mm x 42 mm (1.65 x 1.65) (4) Compression Ratio: 6.60:1... - Page 4 'Transmission (1) Clutch: Manual, Multi. disc in oil Manual, Multi. disc in oil (2) Transmission: 4 speed constant mesh 4 speed constant mesh gear & foot control gear & foot control (3) Gear Ratio: Primary (Hel. gr.) 1 : 4.05 1 : 4.05 Gear Box: 1st: 1 : 2.92 1 : 2.92...
- Page 5 SPECIFICATIONS 90 cc *Engine: (1) Type: 2-stroke. Single Cylinder (2) Piston Displacement: 88 c.c. (5.39 cu-inch) (3) Bore & Stroke: 50 mm x 45 mm (1.97 x 1.77 inch) (4) Compression Ratio: 6.8 : 1 (5) Max. Brake H.P. 7.8 HP/7000 rpm. (8.8 HP/8000 - 90 Spt) (6) Max.
- Page 6 •Transmission (1) Clutch: Manual, Multiple discs in oil bath (2) Transmission: 4 speed constant-mesh gear & foot control (3) Gear Ratio: Primary (Helical Gear): 1 : 3.95 1st: 1: 2.77 2nd: 1: 1.72 3rd: 1: 1.23 4th: 1: 0.924 Secondary (Chain): 1 : 2.43 Total Gear Ratio: 1st: 1 : 26.58...
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Page 7: Dual Twin
SPECIFICATIONS 175 Dual Twin *Engine (1) Type : 2-stroke, Dual Cylinders (2) Piston Displacement: 177 cc. (10.8 cu-inch) (3) Bore & Stroke: 50 mm × 45 mm (1.97 × 1.77 inch) (4) Compression Ratio: 9.5: 1 (5) Max. Brake Horsepower: 20HP/8,000 rpm (6) Max. - Page 8 *Transmission ( 1 ) Clutch : Manual, Multiple discs in oil bath. ( 2 ) Transmission : Dual Transmission, selective 4-speed constant mesh-rotary or 5-speed constant mesh-return by shifting "sportshift" lever ( 3 ) Gear Ratios: Primary (Helical gear) : 1:3.41 Gear Box: 1:2.61...
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Page 9: Engine Disassembly & Reassembly
6. Insert a screw driver through the access aperture and loosen the carburetor mounting bolt. (Fig. 2) 50 Sport, 60 Sport and 90cc models 7. Disconnect the fuel line from the fuel cock. Most service can be performed on the engine 8. - Page 10 Withdraw the engine in this operation. This is provided in the mounting bolts from the left hand side of the Bridgestone special tool kit. machine. 26. Position the engine on the bench, magneto 20. Lower the engine out of the frame.
- Page 11 29. Carefully mark the position of the magneto 35. Remove the 6 clutch springs. armature plate relative to the crankcase with a prick punch or with a felt marking pen. 36. Flatten the up turned sides of the bend These reference marks will make it possible to washer and remove the clutch retaining nut reinstall the magneto armature plate in on the 90cc engine after shifting the...
- Page 12 41. To remove the rotary valve disc, insert your finger up through the bottom of the fuel inlet port and gently dislodge the rotary valve disc from the crankshaft collar. If a screw driver is used to assist in removing the disc, use extreme caution to avoid damaging any part of the rotary valve cavity.
- Page 13 53. Inspect the two transmission shafts and gears to be certain that they are all in good 56. Withdraw the crankshaft assembly. Notice condition. Further disassembly of the that spacing shims are used on either side of transmission is not necessary unless one or the crankshaft balance assembly.
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Page 14: Reassembly
II. REASSEMBLY 6. Holding both shafts and shift drum together as a unit, install the transmission assembly into All parts installed inside the two crankcase the crankcase half. When the shafts have been halves are installed into the magneto clutch partially inserted, rotate them slightly to mesh section. - Page 15 return spring before inserting the retaining screw. The collar goes beneath the shift drum stopper. Tighten the shift drum stopper pivot screw securely. 14. Install the snap ring on the kick starter shaft. 15. Using a needle-nosed pliers, install the crankshaft collar locating pin into the crankshaft.
- Page 16 25. Install the 6 clutch springs and reinstall the clutch thrust plate using the 6 thrust plate bolts. Tighten them securely. 26. If the clutch release push screw has been removed from the transmission cover, reinstall it from the inside so that the flats of the screws (as seen from the outside of the transmission cover) are in a relatively horizontal position with the back of the release...
- Page 17 11. Remove the cover plate on which the transmission selector lever is mounted. BRIDGESTONE 175 DT ENGINE 12. Remove the gear shift pedal. DISASSEMBLY AND REASSEMBLY 13. Raise the carburetor rubber cap from the top I.
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Page 18: Engine Disassembly
1. With the engine placed on a suitable bench, remove the cylinder heads and cylinders. 2. Remove the piston pin retaining clips and, using the piston pin pusher from the Bridgestone Special Tool Kit, remove the piston pins and pistons. - Page 19 15. Place the clutch stopper, a special tool, in place to hold the clutch stationary while the clutch retaining nut is removed. 10. Remove the rotary valve from the crankshaft. Removal can be facilitated by inserting your index finger through the fuel 16.
- Page 20 20. Remove the right rotary valve and collar. It is not necessary to remove the spline from the crankshaft. 21. Mount the flywheel puller in the threaded holes provided in the generator gear and with the center bolt of the special tool bearing against the generator gear bolt, remove the generator gear from the tapered generator shaft.
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Page 21: Engine Reassembly
33. Lift the fifth speed shift fork to the right so 40. Remove the spring clip which retains the kick that the guide pin spring and spring seat can starter shaft in the lower crankcase section. be removed from the shift fork. 34. - Page 22 continuity tester lead grounded, again rotate the shaft until the continuity tester bulb lights. If the bulb will not light in both positions, check the installation of the switch contact and, if it is out of round, replace it. 4. Place the fifth speed shift fork into the transmission case so that the guide pin boss faces the transmission selector lever shaft.
- Page 23 19. Coat the abutting surfaces of the two crankcase sections with a rubber-base gasket compound such as Pliobond. 20. Install the 2 knock pins into the upper crankcase section and join the two sections. Place all of the joining bolts into the holes provided for them and check to see that approximately ½...
- Page 24 Left and right sides of the engine are determined by facing the direction in which 30. Locate the two punch marks on the clutch the machine travels. gear. These marks are located between gear teeth approximately three inches apart. 31. Install the clutch onto the transmission countershaft.
- Page 25 38. Install the generator strap and mount the 42. Install the knock pins into the crankcase generator. Do not tighten the generator assembly and place a new gasket over the mounting bolts securely. knock pins. 39. Again, facing the right hand side install the 43.
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Page 26: Installing Engine Into Frame
54. Replace the oil level screw and fiber washer IV. INSTALLING ENGINE INTO FRAME and install the right hand oil pump attaching screw. Tighten securely. 1. Position the engine in the frame and install the two rear mounting bolts. Install the front mounting bolts and attaching plates and tighten securely. -
Page 27: Construction And Operation
As soon as heavy exhaust is seen coming from the mufflers, the tank may be filled with regular gasoline. D. Be certain that the oil supply tank is filled with Bridgestone 2-cycle oil. CYLINDERS AND PISTONS: A. Construction and Operation:... -
Page 28: Cylinders And Pistons
The cylinders of the 30-60 SPT, 90 STD, 90 T, 90 M are of high-grade cast iron and accurately finished by honing. In the 90 SPT and 175 DT, the cylinders are made of aluminum alloy. Cylinder walls are honed after hard chromium plating and then porous treated. -
Page 29: Crankshaft And Rotary Disc Valves
The crankshaft is one source of vibration. If the crankshaft is not balanced properly, engine vibration will increase. Bridgestone crankshafts are designed to give smooth rotation and balanced operation with a minimum of vibration. -
Page 30: Rotary Valve Modification
Fig. 56. Component parts of rotary disc valve B. Rotary Valve Modification The rotary valves were redesigned early in 1965 to eliminate the steel hub which was formerly molded into the valve disc. The valve now fits onto a separate splined collar. Old style valves can be replaced by the new style valves by also installing the new splined collar and a new (shorter) crankshaft drive pin. -
Page 31: Dual Twin
KICK STARTER MECHANISM: Construction and Operation. All Bridgestone rotary valve models are equipped with the primary kick starting system. In this method, the engine can be started in any gear by simply squeezing the clutch. This is possible because this system employs an extra set of gears for by-passing the clutch in starting the engine. - Page 32 50 Sport, 60 Sport and 90cc KICK MECHANISM: As shown in Figure 62, the kick idle gear A meshes with the driven gear, kick idle gear B meshes with kick idle gear A, and the kick gear meshes with kick idle gear B. Since the kick gear is always in mesh with kick idle gear B, the force created by turning the kick pedal is transmitted from kick gear, through kick idle gear B, kick idle gear A, driven gear and pinion gear, to the crankshaft and starts the engine.
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Page 33: Clutch
CLUTCH: A. Construction:... -
Page 34: Operation
The clutch on all Bridgestone rotary disc models is a multiple disc type, running in oil. The clutch is mounted on the transmission countershaft. Clutch friction (fiber) plates are fitted inside the clutch housing with six teeth so that they turn with the clutch housing and driven gear. Clutch friction plates and inner plates are fitted alternately (steel plate first, then fibre plate, etc.) with the inner (steel) plates fitted to the... - Page 35 the distance, out to increase the distance. When properly positioned, secure with cable adjuster lock nut.) 3. Loosen clutch adjusting screw lock nut and turn screw in (clockwise) until you feel it just touch the clutch throw-out bearing. Then turn screw out (counter-clockwise) ¼ turn. 4.
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Page 36: Transmission
TRANSMISSION: A. Construction and Operation (Fig. 67) BS 50 60 Sport 90 cc Transmission Mechanism in Neutral Gear Position. The transmission in the rotary valve engines is of a constant mesh, rotary type, running in oil. In the 50, 60 Sport and 90 cc engines, the transmission is 4-speed. -
Page 37: Gear Shift Mechanism
The gears are so installed that the drive dogs on one gear engage the holes in the gear next to it. Gears are never installed with drive dogs facing each other. Also, the respective gears will fit only one shaft properly. Hence, all gears will mesh and drive dogs will properly engage the neighboring gears. - Page 38 The gearshift lever is located on the left side of the cycle and is foot-operated. Each time the front of the lever is depressed or lifted, the transmission is shifted either one gear up or down, respectively. Pedal pushed down front with foot once showing drum advanced one notch, (engaging 1st gear) 2 and Neutral follow in succession.
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Page 39: Gear Shift Operation
Bridgestone 175's manufactured before November, 1965, (Serial No. 16W02913) were equipped with the old style shift drum on which there were two neutral positions. As illustrated above right, one neutral was positioned between 1st and 2nd gear, the other between 4th and 5th gears. - Page 40 The fifth speed shift fork on B/S 175 has been modified after serial No. l6B04739. The changes include a guide pin in the crankcase, a new shift fork and 5 gear B. The new shift fork and gear are interchangeable in sets only.
- Page 41 The second Gear A remaining in position, the Third Gear B slides to the left and the claws on this gear engage with the Second Gear B. The engine power is transmitted in the order of driven gear-clutch-countershaft-Second Gear A-Second Gear B-Third Gear B-driveshaft and drive sprocket.
- Page 42 Fourth Gear: The third Gear B remaining in position, the Second Gear A slides to the left and the dog teeth engage with the Fourth Gear A. The engine power is transmitted in the order of driven gear-clutch-countershaft-Second Gear A-Fourth Gear A-Fourth Gear B-driveshaft and drive sprocket.
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Page 43: Gear Ratios
D. Gear Ratios: Number of Teeth Transmission Gear Ratio Gear Countershaft Drive Shaft 50,60 Spt. 2.92 90 cc 2.77 175 DT 2.61 1.83 1.72 1.67 1.32 1.23 1.24 1.00 0.924 1.00 175 DT 0.85... -
Page 44: Carburetor
CARBURETOR: A. Construction and Operation: The Bridgestone rotary valve models are equipped with Amal-type carburetors, i.e. those which control both the fuel and air flow. The air passing through the air cleaner enters the carburetor venturi. The vacuum created in the venturi by this flow of air causes the fuel in the float chamber to be drawn through the main jet, needle jet and then through the passage to the fuel inlet port. - Page 45 When the kick starter lever is depressed with the throttle valve closed, air induction is generated behind the throttle valve by the engine suction. This condition is similar to that created when the choke of a conventional carburetor is fully closed. As the throttle valve is closed, air is inhaled only through the starter air channel.
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Page 46: Functions Of Various Parts
Listed below are the carburetor main jet sizes that are used as standard equipment on the Bridgestone rotary valve models. Also listed are other sizes that are available. -
Page 47: Adjustment
The air jet controls the flow of air entering the needle jet. The fuel passing through the needle jet mixes with the air coming in from the air jet. (3) Needle Jet At full throttle or at medium speeds, the fuel is first regulated by the main jet and the needle jet acting simultaneously. -
Page 48: To Adjust Float Level
MODEL ADJUSTMENT BS 50-60 Sport 1¾ turns BS 90STD, 90D, 90T, 90M 1¾ turns BS 90 Sport 1½ turns BS 175 DT 1½ turns (4) With the engine running, adjust idle speed with idle speed adjusting screw to the lowest RPM possible without stalling engine. (5) Turn idle mixture screw 1/2 turn in either direction until point is found where idle RPM is highest. -
Page 49: Oil Injection System - 90Cc
In the Bridgestone Oil Injection System, a premixed fuel is not necessary; gasoline and oil are supplied separately to the engine. -
Page 50: Adjustment
When the throttle grip is wide open, the cam of the control lever contacts the rod (c) at its highest point, thereby shifting the rod (c) to the right (arrow A). The distance of shift of the plunger is lengthened, and the volume of oil increased. B. -
Page 51: Special Attention To The Oil Injection System
2. Assemble the gear case gasket and housing in place and reinstall 3 screws, fastening securely. 3. Place a small quantity of oil in the gear case housing and reassemble the pump onto the engine, but do not install the mounting screws. 4. -
Page 52: Oil Injection System - 175Dt
• NOTE: Pinch part A first, then pinch part B; repeat alternately until air bubbles are eliminated and the oil flows freely out of the union bolt. 5. Tighten the oil inlet union bolt and repeat pinching with fingers; check the oil flow in the outlet tube (transparent) to the inlet in the rotary valve cover. -
Page 53: Adjustment
When the throttle is closed, the lobe of the stop cam limits the down stroke of the Plunger resulting in a short stroke. This short stroke of the Plunger reduces the amount of oil pumped at idle. As the throttle is opened, the Control Arm rotates the eccentric Stop Cam so that the length of the Plunger's stroke is progressively increased, resulting in an increased volume of oil being pumped to the injectors. -
Page 54: Special Attention - Pump Modification
C. Special Attention — Pump Modification Bridgestone 175 Dual-Twins manufactured after October, 1965, are equipped with a modified oil injection pump. The new pump is equipped with ball and spring check valves in each of the pump body oil outlets. -
Page 55: Electrical Equipment - 50, 60 Sport, 90Cc
The new connectors are easily identified because they are made of brass instead of aluminum. These new connectors are interchangeable on any of the old type pumps. When they are installed on old type pumps, the ball and spring must be eliminated from the connecting bolts. Any old type pump can be converted to the latest style by installing 2 of these new outlet connectors. -
Page 56: Condenser
which the lowest meter reading occurs or at which the continuity tester light dims. (Note that the ohm meter never reads "0" or the light never goes out entirely because the condenser is grounded). This is the point at which the spark plug fires. 5. -
Page 57: Testing The Ignition Coil
KEY TO USE CODE: A Standard plug for break-in and normal use. B Hotter plug for low speed use and when standard plug fouls easily. C Colder plug for high speed use and when standard plug burns easily. D Cold plug. Standard for competition use. E Extremely cold plug for high speed racing. -
Page 58: Testing The Lighting Coil
E. Testing the Lighting Coil: The efficiency of the lighting coil can be checked by connecting an ammeter of approximately 2 ampere reading capacity in series with the battery fuse as indicated in the drawing below. Start the engine and measure the current at approximately 2,500 rpm's and approximately 8,000 rpm's. -
Page 59: Electrical Equipment - 175 Dt
2. For chronic problems caused from the cycle being driven only at very low speeds, the charging coil from the B/S 7 Standard can be installed to increase charging. NOTE: When either method is used, battery water should be checked frequently and water added as necessary. -
Page 60: Right Cylinder Timing Adjustment
• NOTE: As you face the open end of the generator, the points and condenser set on your right, control the firing of the right cylinder. (See Figure 114.) 7. Rotate engine backwards by turning the rear wheel backwards until the right points close and test light is on. -
Page 61: Technical Standards
This high voltage current is supplied .to the spark plugs. The Bridgestone 175 DT has a battery ignition system. Twelve volt battery current flows into the primary coil of the ignition coil. When this primary current is cut off suddenly by the operation of the contact breaker, high voltage current is induced in the secondary coil. -
Page 62: Selenium Rectifier
H. Spark plugs: NGK B-8H spark plugs are standard for the Bridgestone 175 DT. Be sure to use the proper spark plugs as the engine cannot develop 100 percent performance if an incorrect spark plug is used. The spark plug is... -
Page 63: Dry Charged Storage Batteries
carbon accumulates on it, use a hot type of spark plug, that is one with a smaller number. If the insulator has a bleached appearance, use a cold type of spark plug, or one with a larger number. IF PLUG FOULS IF PLUG BURNS BRAND STANDARD... - Page 64 2. Allow battery to stand for 2-8 hours without charging. 3. Inspect liquid level and add more electrolyte, if necessary. 4. Measure specific gravity with a hydrometer. Table 1 indicates the approximate degree to which the battery is charged (stated as percent charged) and the approximate ampere/hours of charge which will be necessary to bring the battery to a fully charged condition.
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Page 65: Front Fork
NOTE: The front fork assemblies on the B/S 50 Sport model with serial numbers before 13N are sealed units. For these units the above instructions are not applicable. (Loss of fluid would require replacement of the entire inner tube assembly. ) - Page 66 1. To assemble fork, place the cover guide over the inner tube so that it rests on the spring. 2. Insert the fork assembly into the fork cover until the cover guide appears in the slot in the fork cover. 3.
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Page 67: Rear Suspension
REAR SUSPENSION: The rear suspension system absorbs shocks in a similar manner to the front fork during operation. The rear suspension units are installed between the frame and the rear fork. The rear fork moves up and down, pivoting on a shaft which fits it to the frame. FRONT WHEEL: The front wheel brake is installed on the right side of the machine. -
Page 68: Rear Wheel
• Screw in for more play and out for less. • Lift front wheel and spin to check for brake drag. NOTE: The B/S 175 DT is equipped with the double cams on the brake drum to assure powerful braking performance. (1) The play in the brake lever may be adjusted while running with the screw adjuster on the lever (2) With the adjusting lock nuts on the front panel. -
Page 69: Adjusting Rear Brake
4. Remove rear shaft nut on left side (the big nut need not be touched.) 5. Pull out rear shaft together with chain adjuster. 6. Removing rear hub collar, wheel will come off the drive flange on the right side. •... -
Page 70: Pre-Delivery Service
PRE-DELIVERY SERVICE After the cycle has been uncrated and assembled, the following service and adjustments must be made to insure proper functioning of the machine: B/S 90 w/Oil Injection 1. OIL INJECTION: Fill the oil supply tank with a good grade of 2-cycle oil (for best results use Rockford oil). - Page 71 6. ADJUSTMENTS: A. Tire pressure 24 to 26 lbs. front; 26 to 30 lbs. rear. B. Brakes: Check and adjust as described in Owners' Manual. C. Horn: Check for proper operation. D. Lights: Check all lights for proper operation. E. Axle Nuts: Be certain that both the front and rear axles are properly secured. F.
- Page 72 B. Brakes check and adjust as described in owner's manual. C. Horn check for proper operation. D. Lights check all lights for proper operation. E. Axle Nuts be certain both front and rear axles are properly secured. Cotter pin must be installed in castle nut on front axle.
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Page 73: Troubleshooting: Engine
TROUBLESHOOTING: ENGINE Troubleshooting is a broad category. It covers the search for the cause of such complaints as hard starting, poor acceleration, poor top speed, engine missing, over-heating, short spark plug life, scoring, rough low-speed operation and a multitude of other symptoms. Regardless of the complaint, the best approach to solving any difficulty is a systematic approach which is followed regardless of the nature of the complaint. - Page 74 It will be fouled: (A) Oil Fouled. Wet oil deposits. Minor electrode wear. (B) Deposit Fouling. Red, yellow, brown, and white deposits indicate use of incorrect oil or high test gas. A. PLUG APPEARS NORMAL Check spark with gap tester. Electrodes should be spaced ¼” apart. "Good" spark will easily jump this gap. WEAK SPARK NO SPARK STRONG SPARK...
- Page 75 B. BURNED PLUG • Check spark with gap tester. WEAK SPARK GOOD SPARK (Not likely) (1) TIMING (a) Advanced (2) FUEL SYSTEM (a) Insufficient Oil (b) Incorrect oil pump adjustment (3) CARBURETION (a) Jets or passages plugged (b) Jet needle adjustment (c) Incorrect main jet (4) COMPRESSION (a) Cylinder packing...
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Page 76: Engine Overheating
3. Avoid fast shifting through the gears. 4. Avoid overloading. • Once a Bridgestone cycle is broken in properly, it is the most trouble-free machine available as attested to by the number of large rental operators who are discontinuing other makes in favor of Bridgestone. -
Page 77: Troubleshooting: Transmission
D. Incorrect Spark Plug in Use. A spark plug not recommended for use under the particular operating conditions can result in overheating. Select the correct plug recommended for this particular model you may be working on. E. Spark Plug Incorrectly Gapped. An incorrectly gapped plug can effect ignition timing. The problem is most frequently found when an American-made plug is installed. -
Page 78: Troubleshooting: Electrical
(4) Check shafts for straightness. (5) Check the shift forks. Are they bent or broken? (6) Check the shift pins (end of shift drum). Are there any broken or missing ? TROUBLESHOOTING: ELECTRICAL 50, 60 Spt; 90cc I. KEY SWITCH If a grounded test light does not light with the switch in the "on"... -
Page 79: Head Light
Connect a grounded light bulb to the hot wire of the switch. It should light if the battery is charged and the key switch is O.K. Now connect it to the other lead from the switch. It should light when the brake pedal is pressed. -
Page 80: All Models
considered faulty. If this test was normal, check the other half of the rectifier by using the red post and touching the yellow, blue, and white and proceed as above. • If no positive conclusion can be made from this test, substitute another rectifier and test as in #2. 7. -
Page 81: Inspection And Maintenance
Check the fuse. Check the charging coil with an ohmmeter according to the specifications under Electrical Equipment, Section C, page 59. INSPECTION AND MAINTENANCE 1. Periodic Checking: 400 km (250 miles) 3,000 km (2,000 miles) 6,000 km (3,500 miles) AFTER ONCE ONCE BREAK-IN... -
Page 82: Service Standards
(6,000 miles) (6,000 miles) 220cc. of hydraulic jack oil (or mixture of 70 parts of Spindle oil SAE #60 to 30 parts of # 30 motor oil) SERVICE STANDARDS CYLINDER COMPRESSION STANDARD MINIMUM 50, 60 Spt: 90 : 110 P.S.I. 120 P.S.I. 90 P.S.I. 100 P.S.I. 175 DT: 120 P.S.I. -
Page 83: Appendix
Spark Plug ....175 in./lb. 5mm Bolts ....40 in./lb. 6mm Bolts ....60 in./lb. 8mm Bolts . -
Page 84: Conversions
CONVERSIONS Multiply To obtain Volume 0.061 Cubic inches Cubic centimeters Cubic inches 16.387 Cubic centimeters Liters 0.264 Gallons Gallons 3.785 Liters Liters 1.057 Quarts Quarts 0.946 Liters Cubic centimeters 0.0339 Fluid ounces Fluid ounces 29.57 Cubic centimeters Length Millimeters 0.03937 Inches Inches 25.4... -
Page 85: Examples Of Conversions
EXAMPLES OF CONVERSIONS 1. To convert 250 cubic centimeters to cubic inches, multiply 250 cubic centimeters by 0.061: 250 × 0.061 = 15.25 cubic inches 2. To convert 0.65 inch to millimeters, multiply 0.65 inch by 25.4: 0.65 × 25.4 = 16.51 millimeters 3, To convert 76 kilograms to pounds, multiply 76 kilograms by 2.205: 76 ×... -
Page 86: Piston Displacement
PISTON DISPLACEMENT The formula for finding piston displacement can be expressed as: D = B × R × S × N D = Piston displacement B = 3.14159265359 (a constant) S = Piston stroke N = Number of cylinders R = Radius of one cylinder (one-half of bore) , read “R squared”, means R multiplied by itself) Example 1 A single cylinder engine has a bore of 70 millimeters, and a stroke of 62 millimeters. -
Page 87: Horsepower And Torque
Example An engine has a piston displacement of 244.6 cubic centimeters and a combustion chamber volume of 41.5 cubic centimeters. What is its compression ratio? 244.6+38.2 282.8 7.4 to 1 (rounded off) Compression ratio = 38.2 38.2 HORSEPOWER AND TORQUE There is sometimes confusion about horsepower and torque. -
Page 88: Gear Ratio
Speed = 2,083 feet per minute GEAR RATIO Gear ratio is defined as the number of revolutions a driving gear makes to turn a driven gear through one complete revolution. By convention, a 4 to 1 gear ratio is said to be lower than a 2.5 to 1 ratio. Note that it is possible to have a gear ratio of less than unity. -
Page 89: Bolt Torque
BOLT TORQUE The following table lists nominal tightening torque for various metric thread sizes: BOLT TIGHTENING TORQUES Diameter Pitch Torque (Millimeters) (Millimeters) Foot-pounds (Meter-kilograms) Coarse thread 0.90 2.53 - 3.47 (0.35 - 0.48) 1.00 4.56 - 6.37 (0.63 - 0.88) 1.25 11.6 - 15.9 (1.6 - 2.2) - Page 90 BS175DT 50 Sport 60 Sport...
- Page 91 90 Mountain 90 Sport 90 Trail...
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