i'm doing a rebuild on my '91 LT250r.
in february the bike toasted the top end, and i just got a chance to tear into it. i took the cylinder off & found a pist on tat was missing a chunk out of the back. the top of the piston had some dings & the head has some very minor dings & scratches, i'm having a local shop do the bore(.020" over)

i'm not afraid to jump into it as engine work is nothing new to me(just rebuilt the top end on my totota pickup, new timing chain & re-cammed it.) but this is the first time i have done any engine work on my LT or any 2-stroke. i think it needs a bottom end rebuild as well b/c the rod can slide side-to-side about 5-8mm, but it has very little play(almost none) if i rock it back & forth on the bearing or pull up/down on it...
for those of you that have done work on LT's, is this normal?
must i do the bottom end as well? or can i just clean out the cases real well? & how?

 

When i done my lower half, my bearing was the same way. I think the lower rod is made to"float" back and forth on the bearing, but centers itself. It is good if there is no play up&down.
Do the main bearings and seals if never done before, this is easy and usually needed after 10 years.
If that shop uses a Seizeco piston(wiseco), Check the clearance on the bore. If it is under 4 thous, it will seize!!

 

2 STROKES ARE EASY IF YOU HAVE ANY KIND OF MOTOR EXPERIENCE. AS FOR THAT SIDE TO SIDE PLAY THERE IS SOME PLAY THERE. GO GET A FACTORY OR CLYMER SHOP MANUAL TO GET ALL THE TOLERENCES TO CHECK YOURS. IF YOU DO TEAR INTO THE BOTTOM HAVE THE CASES MACHINED OUT WHERE THE MAIN BEARINGS GO AND HAVE STEEL INSERTS MACHINE IN. THIS WILL BULLETPROOF THE CRANK. TUDORS PERFORMANCE OR CT CAN DO THIS FOR YOU. IT IS WELL WORTH IT IF YOU ARE ALREADY SPLITTING THE CASES. AND AS FOR WIESCO PISTONS I HAVE BEEN USING THEM SINCE I BOUGHT MY FIRST ZILLA IN 87 WITH OUT ANY PROBLEMS WHAT SO EVER, AND MINE ARE RUN HARD AND ARE BUILT. IF YOU MISS THE BORE SIZE THAN ANY PISTON WILL SIEZE UP. I HAVE THEM IN OUR 450CC WARRIORS AND OUR POLARIS BIKES AS WELL WITH OUT PROBLEMS. YOU CAN GET A BAD PISTON FROM ANYONE, AND EVERYONE HAS THIER FAVORITES IT YOUR CHOICE.

 

i've gotten all the way down to the point of splitting cases, just haven't split them yet.
the main bearings are rock solid, as are all other bearings that'are in there... i talked to the shop today, they said that a 'full-floater' rod will do as i described above, the piston keeps it located w/ thrust bearings. i think i'll just clean out the cases, replace all the seals & re-lube the bearings w/ fresh oil as instructed by the shop. why fix what isn't broken?

from what 've heard about the inserts, they are only needed on the lt500's.