O/T 2-cycle question.

Sorry for the O/T, but you guys are the sharpest tools in the shed.
My '94 Polaris 4-Wheeler crapped out, and I need it to put up firewood.
It starts good, and seems to idle alright, but as soon as I give it any throttle it just kinda sucks air. The RPMs don't come up, but it stays running. Not even enough power to move itself. I let off the gas, and it goes back to idle just fine...
It seemed fine the other day, then blaaaaaaaaa.
Any ideas?
I did try a new plug, but no improvement.

Again, sorry for the O/T, but I need this thing, and there isn't anyplace to take it.


Thanks,
JOE

 

i think you may have a leak in the crankcase,either a crankshaft end seal or the base gasket between the cylinder and crankcase.i've had what you describe happen to me on both my snowmobile and dirt bike,the bike it was a gasket and the sled a crankshaft seal. i'm not an expert on 2-cycle engines,but i know they need a pressure buildup in the crankcase as the piston goes down to force more fuel/air mixture into the clylinder. my sled also uses this pressure to operate the diaghram in the tilitson carbuator to pump fuel up to the carb. like i said,i'm not an expert on them,but this is where i'd start looking...

if it has a diaghram type carb and the diaghram is shot,or has a hole in it,it will run bad too. do you know if it has a diaghram or float type carb?

good luck...greg

 

Fresh gas? Clean air filter? Is that a reed valve motor?

 

I don't know if this helps but years ago I had something like your discribing on a fire pump. It would start just fine. I rebuilt and changed all kinds of shit. On the second day I noticed the spark advance linkage was off. This was a 2 cyl 2 stroke simalar to an outboard. Tim

 

Pull the fuel bowls and check for silt/trash/water. Check for proper fuel delivery....fuel filter change lately, collapsed fuel lines, clean/fresh fuel?

How's that air filter looking?

Does this motor have a spark arrester *screen* in/on the exhaust? They'll clog with exhaust sludge and kill the motor. Lots of saws and other small motors run them....your Polaris may or may not.

Any rodents climb up the exhaust system or into the air box?

Crankcase seals are a good possibility. Lots of hours on the motor? Whats the cranking compression?

-Mike.

 

Sounds like you needa replace the carb diaphragm... Little rubber sheet, they die after a few years.