Suzuki lt 80 top end seized after rebuild

[Michaeld]

I recently had a top end rebuild done and after the 3rd time out on it after rebuild the piston has seized any ideas what could have caused this

[davefrombc]

Since it is  a  2  stroke  it requires an  oil /gas  mix .  My  guess is  either  the  oil  injection  pump has  quit  working  or  it  was  out of oil .  A  lot  of  LT 80  owners just  premix  the   gas and  oil  and  forget the  injector.  Here  are instructions  stolen from another forum  on  completely removing the   injector  pump.  Most   owners recommend  a  32/1 oil mix although some  say  a   40   or  50/1 mix  works for them .  I'd  go  with the  32/1.

LT 80 Oil injection/premix

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If you want to DC it, I would just pull everything off and keep it in the event you ever want to put it back on.
Chances are you won't, but it would only take a minute to put it all back on if needed.
To disconnect, pull the cover on the left side where you access the clutches. (not the small round one, but the whole side cover)..
There will be a plastic piece on the front clutch that turns the oil pump, just pull that off.
If you just want to DC it and leave everything intact, that should be all you need to do.
You probably could plug the hose coming from the resevoir and then hook it back up, but not sure if that's necessary to prevent some minor draining into the carb.

To completely take it all off...........
Disconnect the hose coming from the oil resevoir. If you want to keep it attached, plug the end and roll it up and wire tie it out of sight.
If you want to remove the pump itself, you can fabricate a cover that will bolt right on. Use the bottom of the pump as a template. Or you can order a block off kit I believe.
Pull the tube from the carburetor and plug that hole.
 

[Michaeld]

Ok thanks davefrombc. Is there any way of checking the oil pump is working. The 2 stroke self mixer was full when it seized 

[davefrombc]

The  only way  I  can  think  of  would be to  disconnect  the  line  from the oil  injector  pump at the  carb and  temporarily  plug  the  fitting so  you wouldn't  have  a vacuum leak. .  Fill  the   gas tank with 32/1 mix  and run  the  engine ..  See  if  oil  comes  out  of the  line  from  the  pump to the  carb.  I suspect t  is   exactly  because of an  unreliability of  that oil  pump  that  so  many  eliminate it  and  go  for  premix.       Your  piston  displays   the classic scuff marks  of    an  oil starved  2  stroke.

[LT80]

"Fill  the   gas tank with 32/1 mix  and run  the  engine ..  See  if  oil  comes  out  of the  line  from  the  pump to the  carb." 

I agree..

What piston did you use? China kit? It stick on the intake side?

[Michaeld]

Ok thanks i will try this once i put the new barrell and piston in. 

[Michaeld]

This was the kit i used

[LT80]

Some work, some don't. I run a ball hone thru them and make sure the ring gap is right (been tight when I look/no gap).

hopefully you didn't replace the studs, they are weak.