I bought a 87 lt-500r a couple weeks ago and am in the process of going through the motor. It has a 2.5mm over sized piston, now I checked what the overall cc is with this piston and it makes it 530cc's. Now my ? is, I look in Rocky Mountain ATV catalog and see that they offer 3 wiseco piston's. .020 and .040 above STD bore. Then I went to Wisco Piston's website and found they go as high as 3.5mm over sized. My question is this is this a stock size sleeve with bores? and if so, I am able to do 2 more bores on it right?

Another ?, It also seem to have a spacer plate in it, its small but its too big to be a gasket I think. Could this thing have a longer rod in it or could the base gasket be bigger since the head is O-ringed? The motor so far has a Trinity stage IV port job, O-ringed head, FMF pipe, larger carb(not sure what size, but not stock. if ya can tell me how to find out I would appriciate it). Any help is appriciated.

Thanks
Allen

 

Wiesco's site is correct. You can bore the stock cylinder that far. However, at the largest overbore the skirts on the bottom of the cylinder are very thin and prone to break off. I was in the very same situation when I rebuilt mine back in April. I had the cylinder sleeved back to standard bore so I could start over again and save the port work that had been done.
The "spacer" could be a couple of things... A "no blow" base gasket from Tudor's performance. Or it could be a spacer installed to compensate for cylinder machining to bring the piston back to zero deck height.

Denny

 

While you're on the subjet of deck height, could you tell me what the deck angle is?[img]i/expressions/face-icon-small-confused.gif[/img]

 

Wish I knew the answer to your queston on the deck angle. I am assuming you mean the angle the cylinder sits on the case from 90 degree's (straight up). My service manual does'nt have any of that info.
I'll bet Harry with Trinity could tell us though.

 

When you say to go back to zero deck height? When the piston is at its highest point how close to the top of the cylinder should it get? Should it be even with the surface?

 

<< When you say to go back to zero deck height? When the piston is at its highest point how close to the top of the cylinder should it get? Should it be even with the surface? >>



Zero deck is when the piston is even or flush with the top of the cylinder at TDC (top dead center). This is ideal for the most compression ratio. Zilla's will tolerate zero deck. (some engines won't).
Your thick gasket to could be used to space the cylinder higher to compensate for machining the top or the bottom of the jug. If your piston is down the bore when @ tdc then using a thinner shim or gasket will raise the piston up and increase the compression ratio.

 

What brand of carb is on the Zilla now?