fglove

Rear cylinder blows fuel out through the carburetor throat! Anyone know what could be the cause. I held my finger over the spark plug hole and it seems as though there is compression. I do not have a compression tester. My guess is bad reed valve. It runs, but it seems like it should run better, like maybe its only running on 2 cylinders.

mtcompeau

almost definitely a reed valve, if it does not seal it will blow backwards through the carb

JUST-IN-TIME

reed yep!!!!!!!!!!!!

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HUMAN BUILT = HUMAN FIXED

fglove

I had already ordered reeds before the post. Just wanted someone else to confirm my diagnosis. That was definitely the problem, one of the tabs was blown back into the cage... no pieces missing... hopefully no cylinder damage. Thanks for the advice. Ski runs better, although new plugs seem to burn rich (dark brown to black)... BR8ES, does anyone know what the gap should be set at? Also, does anyone know what the procedure is for adjusting the carbs?

Pahchay

Do the reeds need to seat tightly when there is no back pressure on them? it looks like over time they develop a slight arc that may let some fuel back through the carb when the piston moves down. I'm guessing that when the piston moves down, it happens quickly enough that it would slam the reeds shut pretty quick, but I may be wrong.

If they develop this "Arc" can they just be flipped over?

Thanks for any advice you experts out there may have on this. Can't wait for summer!

dgold047

BR8ES is the wrong plug book says BR9EYA I had trouble finding them I got them at NAPA auto parts. I burned a hole in side of piston while using BR8ES