we are curently trying to disasemble a 250 two stroke polaris engine old version maybe in the late 80s or early 90s. we have everything ripped apart but the engines crank shaft and need to get the fly wheel off but cant figure out how to do so or even the fin type pully on the other side of the motor i need a motor diagram or someone to explan how to remove either of these thanx

 

Here is the procedure for the 400, I can hope the 250 is the same.

The flywheel nut is left hand thread, remember that or you will be trying and trying and not getting it loose. It is held on by a 'spanner' type nut. This can be loosened with a hammer and punch on the notches of the nut. Remember, left-hand thread.

The pulley comes off by removing the center bolt, and threading in a 3/4 inch FINE threaded bolt. Put a washer or something between the end of the bolt to protect the end of the crankshaft. The bolt threads into the pulley, and presses against the end of the crank, removing the pulley. Tap the bolt head with a hammer to help break it loose.

Farmr

 

I don't remember the flywheel nut on the 250's being left handed, nor "spanner type" (Farmr, are you sure your not thinking the inner nut to pull the balance shaft case off the 400's??)

Once you have the flywheel nut off, you will need an automotive harmonic balancer puller and 3 long 6mm X 1.0mm threaded bolts with washers to attach the puller to the flywheel (there are 3 holes around the flywheel center) - tighten the balancer puller and hit the balancer puller bolt with a hammer to "pop" the flywheel off.

On your "fin pulley" (primary clutch), if you cannot locate a 3/4" Fine thread bolt, a larger automotive gear puller's bolt should be 3/4" Fine thread (Autozone usually has loaner tools)

 

It's a good idea to make sure you're using grade 8 bolts on the puller...also some safety glasses in case one lets go. You can use a little heat (propane torch) but not too much cause your stator is behind the flywheel.

 

Quadwrench, you are probably right. I never took apart a 250 engine. I was just going by what you need to do to split a 400.

Didn't realize they were so different. Sorry for any confusion.

 

While we are on the subject of flywheels I was wondering if I would notice a good difference by getting my flywheel trail lightened. I like the convenience of the electric start. But if I'm not going to notice a good reaction then I will go with the race lightening. I am planning on getting a trail port and wiseco piston and thought that I would pull the flywheel while I had things apart. thanks for any info

Bill

 

The trail lightening does make a difference, but not as much as the race lightening. You grin from ear to ear with the increased throttle response.