Yamaha MM700A, Manual, Page: 78 / 282

72 CHAPTER
9. With an assistant's help, lift up the rear of the snowmo-
bile to drain as
coolant as possible.
Use a primer pump and a suitable length of hose to si-
phon the coolant from the coolant recovery (Figure
27) into a suitable container.
Do not by a hose.
The coolant mixture poisonous in-
very small amount
sickness.
Check the gasket on the drain bolt and replace if worn
or damaged. Reinstall the drain bolt (Figure and
tighten to 13
(1
12. Remove the and, on models so equipped, remove
the rear bumper
13. Remove the bleed bolt
(Figure 31) on the rear heat
exchanger.
14.
Add coolant the coolant cap opening. Use a
mixture of recommended and distilled
water. Coolant capacity is listed in Table 5. adding
coolant, watch the bleed bolt hole (Figure When air
bubbles disappear at the hole, reinstall the bolt and tighten
securely.
15.
Add more coolant then loosen the bleed bolt (Figure
on the water outlet. Continue to add coolant through
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
16. Support the snowmobile with a jack so the track is
clear of the ground.
not anyone to stand
with the and the
engine running.
17. Run the engine at 2500 so the coolant pump cir-
culates coolant through the cooling system, If the coolant
drops, add to maintain the correct level in the
filler (Figure When the coolant level stabilizes,
stop the engine and lower the track to the ground. Install
the coolant cap.
Fill the reservoir to the mask.
19. Reinstall the rear bumper cover and
Close and secure the shroud.
Carbon Removal
Periodically remove carbon buildup from the piston
crowns, cylinder heads, exhaust ports and pipe.
Refer to the maintenance schedule at the end of this
chapter for the recommended removal time. Adjust the re-
moval
period depending on 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 Overheating and preignition
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
with a soft cloth soaked in solvent. If the depos-
its left too long make sure to scrape them off with a
metal scraper.
Remove the carbon using the softest tool that will re-
move the For instance, use a wooden dowel where
possible, then use a metal scraper only where needed. Do
not use pointed metal objects.