I have a 87 shee. It is misfiring on one cylinder @ low rpm and idle. It has 125 psi compression in both cylinders. It has recently been rebuilt. Does anyone have any possiblities of what is going on.

 

I dunno.. but you better check it out before you go riding.. or your banshee ends up like this: http://www.geocities.com/yamahabanshee96/right.jpg

 

Check the plug caps for the proper resistance.

 

Sounds like the problem could be the rubber hose that connects the two carbs together. If this hose is disconnected at either carb, it will run like you described.

This hose is black in color, approx. 4 inches long and approx 3/8" in diameter. It must be connected to the correct vent line on each carb to balance them out.

Good luck!

 

What do you mean misfire? Do you mean it's backfiring? Well if one side is backfiring I would tell you to take the carb off the side that's backfiring and to clean the pilot circuits out and remove and clean the pilot jet.

 

By misfire I mean that it does not seem to fire. It does not backfire. It runs strong mid and top end but real weak at low end.

 

Make sure your carbs are in sync. and make sure the vaccuum tube is hooked up between the carbs.
good luck

 

If the carb slides are not adjusted properly (ie. one opens slightly earlier), then one cylinder will receive fuel while the other will not at low RPM, which could cause the situation you are describing. Check this by removing the air filters/ rubber boot on the back of the carbs, then crack the throttle slightly and look to see if they both open. If they both open in sync, try cleaning the jets.

 

make sure your slides are installed correctly....
(cutaway towards air filter)yes ive seen people do it.....
clean your carbs...
check the connecting hose between carbs...
sycronize your carbs!!!(this is important)...
and put in new plugs...
try that

 

make sure your slides are installed correctly....
(cutaway towards air filter)yes ive seen people do it.....
clean your carbs...
check the connecting hose between carbs...
sycronize your carbs!!!(this is important)...
and put in new plugs...
try that