Banshee wont rev

[CRE Performance]

Hey guys, got a Banshee that has been down a long time and just now got it back together. We dont know the history of this quad or how it ran before. It had an ate up piston in it. We replaced the pistons with .100 over wisecos, it has a coolhead setup, and a motofast 2 into 1 pipe. This thing will idle fine but will not rev for anything, wont even start to. You can peg the throttle, and itll simply make an airbox resonance but doesnt die nor gain. I have removed the carburetors and cleaned them, replaced the jets and they are working properly. Anybody got any insight on this? I know banshees are strange creatures compared to the bikes Ive been working on so Im kind of at a loss right now.

[300ex mxracer]

im bettin there is a air leak somewhere in your crankcase and it is not getting vacuum. you might have put a gasket in wrong or something like that. im not sure how you test crankcase vacuum, youll have to talk to some 2 stroke guys.

[CRE Performance]

Ya know, that will definitely cause it. Just so happens that the last thing I want to hunt for right now. It also happened to be the last thing on my mind because we went completely into this engine and reasealed everthing with new crank bearings and seals and reassembly was meticulous. Any other less intrusive ideas first?

Also, we have new plugs, the air filter is in good shape and the pipe is clean and fresh. It just very wierd becuase this thing wont even try to rev. Just like the throttle was unhooked, but its not. Anything on the lines of an ignition module or stator known to cause anything like this?

[1fst400]

I had a dirtbike that had no power. and would barley rev up. It ended up being an acorn stuck in the reeds holding them open. How that sucker got throu the carb is beyond me.


I have no idear of its one bit possible on a banshee motor. But on a snomobile motor we check for bad crank seals by. Starting the motor and letting it idle. then spray starting fluid at the crank seals. If it revs up then they leak.

[300ex mxracer]

i was going by what my buddy did to his blaster. he did a total overhaul and messed up something. had the exact same symtoms ur has. come to find out the crank seals were leaking.