Reed Valves Affecting Compression?

[outboard geek]

1988 110 Evinrude. Given to me recently. Compression is 110 and 110 on the top cylinders. Bottom cylinders are at 75 and 90. Reed valves are bad (open) on both bottom cylinders ( visually inspected). Could this be why the compression is low? Engine was not winterized, carbs were a mess as were the lower reed vlaves, appeared to be water damaged. Any advice would be appreciated. Thanks

 

[beau123]

Re: Reed Valves Affecting Compression?

If reeds are clearly open replace them. Completly<br />dissasemble cards and soak them.

 

[OBJ]

Re: Reed Valves Affecting Compression?

Welcome aboard iboats outboard geek!<br /><br />The reeds would not effect compression. The reason both bottom cylinders are low is probably because of the lower carb. The lower carb feeds both bottom cylinders.<br /><br />I would pull the heads and see what the cylinders look like inside.<br /><br />As hoss suggested, pull the intake manifold and get a good inspection of the reeds. Replace if needed.

 

[outboard geek]

Re: Reed Valves Affecting Compression?

Thanks - What would the carbs have to do with compression?- If valves are open would that not affect the compressed fuel air mixture entering the cylinder thence lowering the compression? I do not want to pull the heads as the gasket set is rather pricey. Reeds are clearly open on bottom cylinders I checked them with a flashlight. I really do not want to start dropping money into this motor . Outboard geeek is cheap cheap cheap. Sure do appreciate your answers.

 

[Chinewalker]

Re: Reed Valves Affecting Compression?

The carbs would CAUSE the loss of compression in the bottom two cylinders. If they're running lean (not enough fuel getting through) then the bottom two cylinders wouldn't be getting sufficient lubrication, which in turn can cause the pistons to burn up...<br /><br />The reeds affect crankcase compression but would have no effect on cylinder compression...<br /><br />- Scott