Well my once good running 1994 LT80 developed low compression miraculously. It slowly declined in power over a month and now gives a solid 35psi during a compression test, even with a little 30 weight added she still does not gain any compression. We pulled the head and jug and measured the bore dia at 2.009 wich looks to be about 0.030 over the maximum servicable limit in my LT80 manual. The previous owner told me it had been bored once. As I understand the first boring for these engines is at 0.010 and the second is at 0.020. I was not aware that there was even a 0.030 kit for this bike. Am I thinking right that I now need to go to a new or at least a reconditioned jug? Is the jug I have now junk? If so where do you guys recommend getting these parts from? Kind of bummed cuz I think I got taken on this deal on the bike. It ran good for about 2 months and then it lost power. I pulled the reed valves and they looked good. Any ideas?

Thanks guys, got to get this runnin for my boys as summer is here and they want to ride before going back to school.

 

Your cylinder is not wasted.
Zuki only makes pistons to 1.0mm over (first is .5 mm).
After that A Wiseco piston must be used.

 

If I bore the cylinder and buy a weisco piston for it it sounds like I'll have about 140$ in the job. For 180 I can get a brand new Suzuki Jug with piston and gaskets and everything and they are all OEM parts. Am I missing something here? For 40 more bucks I'd rather start over with all new OEM parts and have some life left in the jug to be bored again later on. Is there any other reason this bike would have low compression? The piston looked a little burnt but the sidewalls of the jug looked OK. I'm just hoping this will be what it takes to get her running again.

 

At motorsportssupercenter.com the parts came to $212.75 w/o shipping. Don't know where you got your prices from but these rival the price I get.
That's for cyl, piston kit, base/head gasket, piston pin, pin brg, and clips.
I agree with you. OEM is best. I use all Suzuki parts.

If you did not see a blown head or base gasket, and if the head nuts were tight when you first took it apart, then I'd say it has to be the bore/piston.

I'd like to know what numbers are on top of the piston that you have now.

 

SUZUKI LT80 LT 80 CYLINDER PISTON GASKET KIT HEAD TOP : eBay Motors (item 250671007342 end time Aug-21-10 20:14:00 PDT)

If that link works it should show you what is going on. It has everything you mentioned and it says they are OEM Suzuki parts. The top of the piston I have now has a 10 stamped in it as well as an arrow. We measured the bore at 0.800 down from the top just like the manual I have says to do and got the measurement just over 2" that I posted above. I almost wonder if the piston is undersized and the rings have been overextended?

 

That is very good pricing if it is what they say it is.
You have a 1.0 over piston in it now (.040).

 

It is what they say it is. Just bought one from them, all parts included. The only draw back was shipping was a little slow coming from Canada.