Suzuki LT80 nightmare

[ronald webb]

So where to start my son's LT80 stop running a couple months ago. Naturally I assumed I had a carburetor issues or the peacock valve. After replacing those two items and ensuring I had a spark I started doing my homework thus finding this page. After all the post I have read the next natural thing would be compression I did a compression test today and it was only 60 after spraying WD-40 in it so off comes the cylinder head and The Jug to my surprise the cylinder walls and all the gaskets are pristine so I am totally stumped no idea why I would not have compression when everything looks brand new even the Rings look great any help would be appreciated thanks in advance

[Frank Angerano]

You are missing something, did you wire brush the top of the piston and the head for carbon build up to make sure there aren’t any pinholes or cracks? I would also check the head where the gasket sits to make sure it’s not warped. And lastly the rings could be bad even though they look ok. I would think it’s just a piston and ring replacement job. 

There could be a hairline crack in the cylinder jug or head  but that would probably have shown up with a dark spot or hearing air coming from it. 

I would put a new gasket kit and piston and rings and see where you are at.  

Ive heard of the 50cc engines losing compression from the crank case bearing seals but not on the 80.   

 

 

[ronald webb]

thanks for the advice im going with a new top end piston and rings new reeds and bigger jets👍

 

[Frank Angerano]

Very good. Should be a sold engine after that. 

Good luck and keep us posted. 

[davefrombc]

Reeds not  seating properly  could be  a  big reason  for   some of the loss of  compression and very  poor running .

I wouldn't  change the  jets..  Just   put in new  reeds  and  rings.

 

[Ajmboy]

Topic moved to Suzuki forum.

[Gary Kozdra]

I same quad with similar issues. I rebuilt the top end, rebuilt the carb, and replaced the reed. Starts, runs and idles but has no power.  Cant barely move itself with no one on it. Air filter ok. Sounds like its bogged down with throttle open. Compression test showed 140 psi. Plug looks good. Gaskets look good. Im lost. Any suggestions??????

[LT80DAD]

What is "normal" compression psi for these little engines?  I am most used to old English cars...these are ll new to me.

[shar]

On 7/30/2019 at 10:56 AM, LT80DAD said:

What is "normal" compression psi for these little engines?  I am most used to old English cars...these are ll new to me.

Does anyone have the answer to this question?

[Sampson49]

@Gary Kozdra try removing the muffler. If good then problem is carbon and oil plugged muffler. I had this issue with 2 stroke moped that would hardly pull itself. After cleaning, was strong even with 250 pound rider.

[Mech]

Small 2stroke engines can warp their barrels down where the transfer ports are. It's always a good idea while you have it apart to push a ring down there with the piston and then hold the barrel up to the light and see if you can see light between the ring and the cylinder wall, then push the ring another half inch and check again.. check for warpage right through that area where the transfer ports are.

2strokes can run ok when you only get sixty pounds during a compression test. They are pretty fickle to check the compression on. once they are running the compression is often higher that the sixty.. sixty should still start.

Last time it was going did it get turned off or did it stop by itself ? Was it going good right before it stopped ?

[Hagbard]

Just FYI. Check your starter gear. The one behind the clutch that meshes with the starter bendix.  

 

 

Edited September 15, 2022 by Hagbard

[2002kq300]

Interesting, usually Suzukis are easy to figure out whats wrong

[Mech]

The terms people use to describe problems varies, and is always a source for confusion when trying to diagnose things remotely.. that and varying degrees of experience actually working on machinery make it tricky helping online. What might be obvious immediately to an experienced rider or repairer, can go right off track in here.. 

 Good work Hagbard on fixing his bike, and posting the cure..a good lesson/reminder for all of us..