No. Most all start at 50mm.
Presuming that your machine's stock piston size is 50mm,your looking for a 50.5mm
->BUT, you should see what numbers are on top of the piston you have. You may have a 50.5 in there now. thus you'd need a 51mm piston.
I recommend that you take your piston into the dealer/shop and have them look at the piston and determine the size it is.
Once the correct piston is ordered and resieved, they will bore and hone the cylinder to the piston size.

 

LT80 thanks.

Here is what is on the top of the piston: Cast into the top you have the arrow on the bottom and above the center line is 4DM with an A stamped below the D. There are no other markings on it. I miched the piston and it measures 2.043" or 51.8922mm. The cylinder bore measures 2.048" = 52.0192mm. This is why I was thinking a 52mm piston and have the bore honed a tad to clean it up. What do you think?

Thanks, Jim

 

I indeed stand corrected!!
And you are correct.
With that said, I think now, I'd go to the bore place and ask them if they think the bore is allready to big for the 52mm.
The piston in there may be a 52mm.

You may consider looking up a Canadian company. OEM parts warehouse or something like that. I got the number off ebay.
They sell a new LT80 cylinder,piston kit and gaskets ($119.) for less than what I can freshen a cylinder up (bore and piston).
I'm confident that they sell a cylinder kit for your machine also.
I think that your cylinder is the same as polaris,eton,kasea, and others.
Sorry about the measurement confusion. Thanks for explaining it...again.I am getting old ya know. LOL

 

Jack,
Thanks for all your help. I ended up purchasing an entire top end kit, piston/cylinder/gaskets... Once I get it all back together I'll let everyone know how I made out.

Thanks again, Jim

 

I just got my parts in and I can't wait to install them. It's like Christmas in august. Let's keep our fingers crossed that everything goes back together without any problems. I'll let you know.

JR

 

Started my assembly today. Got everything back together and started to torque the head nuts. 14ft.lbs.????? Man I don't want to snap off a stud. I have a new digital torque wrench and that seems to be a lot for these small nuts. Any thoughts?

Thanks, Jim

 

Well the worst happned. I was worried about snapping off the stud, I did one better, I stripped out the block thread. I kept slowly tightening each head nut with a cross pattern and they just didn't seem to want to get tight. Then I heard a loud "ping" the stug was loose and the threads were gone. I guess now I'll have to install a helicoil to get things back to working order. Always something.

Thanks, Jim

 

The heliciol worked out well and I have everything put back together. Before I put "everything" back on I thought I would start it first. I have spark to the plug, I have fuel to the carb, but it won't start. I pulled the plug and it's dry, so I'm not getting fuel to the chamber. It ran when I took it apart and all I did was change the top end. The cylinder can only go on one way with the exhaust port down. The piston was installed with the arrow pointing down. Can anyone think of anything else that I could have done wrong?

Thanks, Jim

 

Finally got the LG90 running. I made my granddaughter a very happy girl. It has been running good with the new parts. The problem I had today when I started it the rpm's were very high, to the point that it almost took off by itself without me on it. I don't know what happned. I tried to adjust the cable with the jam nut. It helped some but not enough. Any suggestions?

Thanks