Polaris Sportsman 700 - Pressure in valve cover

[NorWayMarius]

Dear All,

My friend has a Sportman 700 whit hydraulic lifters. On this bike it is buliding up a pressure in the valve cover when we are turning the engine around. We see the plastic valve cover moves up and down during turning the engine.

This happens also when both sparkplugs are out.

Any idea what can caise this?

 

Best 

Marius

 

 

[Mech]

Surely air pressure can't flex the cover. If it did, the cover would flex so fast running it would crack in no time.

Check the engine breather is clear and breathing, but then if it keeps doing it I'd suspect the cover is getting pushed from the inside. I know nothing about those tngines but is it possible the cover is on backwards or something, no gasket perhaps, and the valves are hitting ?.

 

[Gwbarm]

Agreed, i think something is pushing on the cover.