Thanks for all the replies. I'm going into the garage to check out the stator and I hope that's not it because of the mucho $$ it costs to replace.

As far as the top end goes, does anyone know what compression I should get when I do a compression test on the top end? I got 150 with a standard spark plug type guage. The Clymer book for the LT250r seemed to have left that out (among other things). The Clymer book for my Yamaha Blaster says a rating between 140-160 is good. Is it the same for the LT250r? This would rule out a blown top end for sure.

Thanks!!

!*mr.bones!*

 

Compression is healthy. Check your stator and key.

 

I have 150 lbs of compression in my 91 lt250 so yours must be good to. I have a pretty fresh rebuild


-chuck

 

Again, thanks for all the replies. All those who said stator, you are correct!! I removed the left side cover and found the flywheel was quite loose. So loose that the whole thing could be removed by hand, no flywheel puller necessary. The key was sheared in half. The flywheel being loose obviously altered the timing of the engine and it sparked whenever it just happened to spin while kick starting the engine, then causing the kick start to bite back at my foot.

I was little surprised at the design of this thing. The last flywheel I took apart was on a Honda ATC90. There was no way that thing was coming off without a puller. It had a built in key on the shaft to keep it from turning instead of using a separate key. But maybe a separate key is better since it is replacable. And I bet any flywheel that has been neglected could come loose. If only I could go smack the guy I bought my LT from, I'd feel better!

But anyway, I'll get a new key tomorrow (3MM WOODRUFF KEY for future reference) and torgue the flywheel down good with lots of loc-tite. I'll have this thing running in no time.

And it's good to know 150 is a good compression rating! At least the previous owner did rebuild the topend like he said and he did it right. You never know when you are buying used stuff. The next time I buy a used ATV, I'm bringing that guage with me!

Thanks!!

!*mr.bones!*

 

Would you believe there isn't one retailer in Tampa, FL that sells metric woodruff keys?!! I've tried 4 motorcycle/ATV shops, 3 autoparts stores, and 2 hardware stores. This is crazy! I can't ride because of a $1 part?! I'd pay $20 for one if someone sold one around here. Crazy, crazy, crazy. Guess I got to order it.

!*mr.bones!*

 

I was wrong about the ATC90. It does use a woodruff key, in fact, I checked my only parts motor from a '72 US90 and found a 3mm key and it works on the LT250r! I'm glad I didn't give it away when I sold the 90. If only I checked that a little closer before I went on a wild goose chase around town. Well, at least I can get the 250 up and running sooner.

BartlettRacing,

Thanks for the tip. I'll do just that. In fact, I'll do it right now!

!*mr.bones!*

 

while you have the flywheel off, check you crank for trueness. my brother had a problem of both the flywheel key and counterbalancer key shearing regularly, turned out the counterbalancer and crank were both bad