Yamaha MM700A Manual page 78

72
9. With an assistant's help, lift up the rear of the snowmo-
bile to drain as much coolant as possible.
phon the coolant from the coolant recovery
27) into a suitable container.
Do not s@hon cuofant by mouth and a hose.
The coolant mixture is poisonous and in-
very small amount may cause
sickness.
or damaged. Reinstall the drain bolt (Figure 3@) and
tighten to 13 N*m (1 15 in.-lb.).
12. Remove the sedt and, on models so equipped, remove
the rear bumper cover.
13. Remove the bleed bolt (Figure 31) on the rear heat
exchanger.
14. Add coolant though the coolant cap opening. Use a
water. Coolant capacity is listed in Table 5. W-hile adding
coolant, watch the bleed bolt hole (Figure 311. When air
bubbles disappear at the hole, reinstall the bolt and tighten
securely.
15. Add more coolant then loosen the bleed bolt (Figure
the filler opening until air bubbles disappear at the bleed
bolt; tighten the bleed bolt securely. Continue to add cool-
ant until the coolant level is even with the filler neck as
shown in Figure 33,
16. Support the snowmobile with a jack so the track is
clear of the ground.
engine running.
17. Run the engine at 2500 rpm so the coolant pump cir-
culates coolant through the cooling system, If the coolant
filler neck (Figure 33). When the coolant level stabilizes,
stop the engine and lower the track to the ground. Install
the coolant cap.
19. Reinstall the rear bumper cover and smt.
Carbon Removal
Periodically remove carbon buildup from the piston
crowns, cylinder heads, exhaust ports and exl~aust pipe.
Refer to the maintenance schedule at the end of this
chapter for the recommended removal time. Adjust the re-
moval interval period depending on the amount of carbon
buildup.
On a two-stroke engine, carbon builds up quickly in the
combustion chamber, on the piston crown, in the cylin-
der's exhaust port and in the exhaust system. The carbon
deposits increase the compression pressure and decrease
engine performance. Overheating and preignition fiom
carbon deposits can cause engine damage.
If the carbon is removed at the specified intervals and a
good grade of two-stroke oil is used, the carbon buildup
will rarely amount to more than a thick film, which can be
its ase left too long make sure to scrape them off with a
Remove the carbon using the softest tool that will re-
move the carbon. For instance, use a wooden dowel where
possible, then use a metal scraper only where needed. Do
not use pointed metal objects.
CHAPTER T H m E