I am new to 2 strokes but have a general knowledge of motors. I am also new to the forum. I bought my kids an lt 80 last summer. Awesome little quads. This one is stock, except for the self oilier removed. This spring it wouldn't run right. It would idle, but no bottom end power. If you picked the rear end off the ground it would come alive, with a load it would bog down and almost stall itself. Here's what I did
Cleaned the carb,
boiled the carb,
cleaned fuel tank,
fresh fuel mixed to 32:1
replaced original pet **** with aftermarket (no vacuum) one,
replaced carb with brand new after market,
checked exhaust for restriction,
checked compression....Found it! 65lbs compression,

So I rebuilt the top end. Completely removed the motor so I could clean everything up. Removed the reeds, cleaned the carb...again. I bought a Wiseco rebuild kit from ebay for $140. Assembled and fired it up...Full disclosure, I did not check ring gap...I oiled everything up, put the arrow toward exhaust side, made sure the rings were seated around the "tit" in the piston, put it together and started it. Idled beautifully....shut it down to let it cool. Fired it back up and putted around the yard, blipping the throttle just enough to keep moving. This did not fix my bottom end problem, still no power. Rechecked my compression...85lbs. Tore it down and my cylinder was shinny...so were the rings...Oops.

So, I bought another top end kit. This time an $80 "Maxpeedingrods" (probably generic) from ebay. This time, I learned a little bit and checked the rig gap. Used the piston to slide the rings in the jug...had .008. according to my manual, this is with in spec. Oiled it, put it together, idled. I was more careful with the break in this go. I put it through three heat cycles before I took it for a ride. I had power, I had to ride with the coke on, figured it was a a carb problem, but I had power. Smoked the "normal" amount. Ran the quad easy (just putting around the yard) for another 5 minutes and the fartin thing locked up. Tore it down, and the front of the piston had rubbed the cylinder and scored both.

Bought another top end, $80 version, checked ring gap, measured both the piston and cylinder to make sure those clearances were with in spec...good to go...In doing more reading and looking I found I was putting the sir clips in wrong. I was putting them in a "C" direction instead of a "U" direction. Soooo, put it all back together. Ran through 3 heat cycles...perfect. Putted around the yard for a bit....PERFECT. All is good! Shut it down, let it cool. Fired it up, let it warm up at idle, putted with it again for a bit...then opened er up. It ran great, had power, sounded good. Shut it down, told the boy his quad was good! He rode for about 5 minutes and it locked up on him. Let it cool down and it would run but we lost bottom end power again. Im at a loss....not the right break in procedure? Cheap rebuild kits? am I missing a step? Im wondering is the bottom end of this thing is bad? But it sounds awesome at idle and when it runs, no knocking. I havent tore this one down yet, but im guessing piston wiped the cylinder again. Please Help!!

 

What an ordeal.
Yes, the 3 Wuhan specials bit you in the ****. imo.
Get a nice Suzuki piston (the next size up) and have your oem cylinder fitted with the new piston.
I can help if need be,. I stock all the parts.
ALTHO...A lot of work but I didn't rear where you serviced the clutchs.

 

LT80, thank you for replying. When I had the motor out during the first rebuild I did "almost" all but split the case. The front clutch looked good, minimal grease, rollers looked nice and round. While I was in there I took two of them out. I put it back together with just enough grease to hold them in place. The rear clutch "looked" good. To be honest, I did not disassemble the rear. There was minimal "dust" in the case and, with a lot of grip strength, I could move the clutch in and out. If you think I need to disassemble the rear clutch I definitely will. I will be in touch about the rebuilds. I have priced out a new .5 piston from a website you recommended in a previous post. I'm kicking around maybe getting port and polish done too. From what I've read you are the guy for that job and might as well get all from one place.

 

Email received.. If you have it apart, I'd remove the rear clutch. The bearings in it are the most wearing parts on a LT80. I replace many.

 

Went ahead and removed the rear clutch. I didn't have it "the motor" apart, but Im trying to do this right so I went a head and did the work. I completely tore everything apart, it was a little dirty but everything seemed to spin freely. Bearings seemed nice and tight (the kind of tight they should be) everything looked in order. They only thing that alarmed me a little was the clutch drum seemed like it got hot...had a blued look to the outside and the inside was shiny. I lightly scuffed up the clutch shoes, they had a glaze on them. Any opinion on the clutch drum?

 

If you stuck your fingers in the bearings to see if then have a bump in them, I think you're good to go.
The drum is normal.
You're doing very good.

 

Yes all smooth, no bumps or rough spots. Thank you for your help and reassurance through all this. Went ahead and ported the reed cage a little while I had it easily accessible. Got a set of Boyesen reeds on the way too...why not. Thanks again LT80, you never disappoint.