Three external adjustments are possible on the carburetor; the high-speed needle, low-speed needle and idle stop screw. Ride the snowmobile for a short distance to fully warm-up the engine. Remove the top access panel and adjust the carburetor in the following manner:
Adjusting Low-Speed Needle
1. Shut off the engine.
2. Carefully turn the low-speed needle clockwise until lightly seated. Do not force.
3. Back needle out I turn (Walbro) or 1-3/4 turns (Bendix). Back needle out 1-1/8 turns on 800 Snowmobile.
4. Start engine.
5. On Walbro carburetors, turn low-speed needle clockwise or counterclockwise until smoothest running and highest rpm is obtained.
NOTE: On machines equipped with Walbro carburetors, keep the low-speed needle adjusted as lean (clockwise) as possible, while still providing smooth idling and unfaltering acceleration. This will reduce spark plug fouling.
6. On Bendix carburetors, turn low-speed needle clockwise slowly until engine falters (looses rpm). Then back needle out 1/4 turn. Readjust idle stop screw as necessary.
Adjusting Idle Stop Screw
The idle stop screw is adjusted only when a change in idle speed is required. Set the idle speed at 2200 to 2600 rpm. Generally, if the idle stop screw is adjusted, the low-speed needle will have to be readjusted.
Adjusting High-Speed Needle
1. Shut off the engine.
2. Carefully turn the high-speed needle clockwise until lightly seated. Do not force.
3. Back needle out (counterclockwise) 3/4 turn (Walbro) and 1-1/2 turns (Bendix). Back needle out 1-1/8 turns on 800 Snowmobile.
4. Start engine and take snowmobile for a highspeed trial run in a large, level area.
5. Stop, turn high-speed needle 1/8 turn or less clockwise, and make another trial run.
6. Continue this procedure, 1/8 turn or less at a time, clockwise or counterclockwise, until optimum performance is obtained.
7. Turn needle 1/8 turn counterclockwise for final adjustment.
Too lean (clockwise) a high speed needle setting can seriously damage your engine. On the 800 Snowmobile DO NOT turn the high-speed needle (clockwise) LESS than I full turn open.
NOTE: High altitude (distance above sea level) requires a leaner carburetor setting. Use the following rule for leanest possible high-speed needle setting.
Above 5000 feet altitude (1524 meters) = 5/8 turn open (300), 1-turn open (400, 600 and 800)
If, after setting high-speed needle correctly, engine falters or hesitates on acceleration, it may be necessary to lean or enrichen low-speed needle slightly to correct this condition.
Never set the high-speed needle with the track off the ground and the engine in a "no-load" situation. Engine must be under load to prevent engine damage from overspeeding and to obtain proper carburetor adjustment. Overspeeding the engine may damage or destroy cooling fan belt.