Two-stroke sled loses top end: carboned exhaust valves
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Applies to: Arctic Cat, Ski-Doo and Polaris two-stroke sleds with exhaust valves
Symptoms
- Flat on top, won't pull past mid-range
- Bogs at mid RPM
- Lots of trail riding at part throttle
Why it happens
Exhaust power valves collect carbon from oil and part-throttle riding until they stick partly closed, choking top-end power.
How to fix it
- Remove the exhaust valves per the manual.
- Soak and clean carbon from the valves and their bores.
- Check bellows, springs and actuators for wear.
- Reinstall and check valve movement; clean at the manual's interval.
Tools and parts
- Carbon cleaner
- Scraper
- Valve gaskets or bellows
What the factory service manual covers
Engine: exhaust valve removal, cleaning interval, actuator test. The full procedure, specs and wiring diagrams are in the factory service manual for your machine.