A thing I do is fill the bottom end up with kerosene or diesel fuelwhile waiting for the top end to be redone. If any dirt or gasket material falls inside, it will float to the top. Biggest thing is, if the fuild leaks out, repalce those crank seals!

 

You have ridden four strokes in the past winter Im guessing. Let me tell you right now, there is a large difference in a 2 stroke and 4 stroke jetting. 4-strokes can comphensate to cold weather much better than 2-strokes can. I am 100% posotive that it DID infact harm the engine. You did not put in a larger main jet to comphensate for the cold weather so your engine was running hot and blew up. 2-strokes and 4-strokes are alot different, learn how to keep your bike running properly and you wont have these problems in the future.[img]i/expressions/face-icon-small-disgusted.gif[/img]

 

Kruzoffman, even if you see no score marks in the cylinder, you could still be out-of-round. Unless your friend used a micrometer during his inspection, he does not know if your cylinder is fine. Way back when I first bought my LT I was told that the motor was just rebuilt a couple months ago by a "racer friend" that was supposed to know about engines. Well the quad only lasted 1 or 2 days under my ownership before a ring caught a port. I tore it down, mic'd the cylinder, and found it to be badly egg shaped. That did not happen in the very limited ride time on that motor. A new piston and rings was obviously slapped into a bad cylinder.

If your quad is jetted properly for the summer months then your are definately too lean in the winter. I have a Digatron EGT on both my snowmobile and my quad. The jets in both have to be upped a number of sizes when going from summer to winter (the sled is occationally used for grass drags). The more modifications your engine has, the more tempermental it is to incorrect jetting. Also, if you baby the engine in the winter, it can probably handle the lean condition. Another possibility is that the jetting you have now is actually too rich for summer (perhaps changed by a previous owner). Then your jetting would not be as far off in the winter. You need to learn how to read plugs and piston wash in order to have any idea where your jetting stands.

 

Apparently everybody missed the post where he said his carb boot was cracked. The air coming in through that crack is what caused the lean condition that siezed the engine. That fact that it was really cold air only made it sieze faster.

The dude is in Alaska and it's february....I think he's been riding in pretty cold weather for a few months now. I definitely think the cylinder should be bored. It's only an extra $40 and it will increase the displacement a little and guarantee the cylinder is round and smooth.

 

hey, sam250. i didn't miss the carb boot prob', i did miss the size of the cc's. the Lt250 shares the same lack of quality as the Lt500. the intake boot was the biggest prob'. broke's reply about the kerosene or diesel is a great idea that been for years.after you do that see if you can rotate the crank, if not put more kero' in the case,lift and stand the front of the quad up to the the grab bar and use a air gun at 50 to 60 psi aimed in the crank area to get the smaller fragmets out. now see if the crank move freely.repet if ness'