Anyone want 555 Big Bore Pistons

[KevinC]

I cooked my race engine last weekend, so I have to get some new pistons. It was a 555 cc big bore engine with pistons form the old V&H kit. V&H and Wiseco (the original makers of the pistons), no longer support it.

JE Pistons will make custom pistons in a minimum quantity of 4. They are going to use my old Wiseco piston as a model. The new pistons will likely be lighter than the Wiseco ones.

You can in theory bore out the stock sleeves to a 79 mm bore for these pistons, but the remaining sleeve is very thin and fragile. I think that the thin sleeve was a primary factor in my engine seizing.

I am going to have a set of cylinders re-sleeved for a 79 mm bore. The cases have to be relieved to accept the bigger sleeves. It may be a good idea to have a groove cut around the top of the sleeve in the cylinders for a soft copper wire to act as an o-ring to seal the higher compression. I have not done this to date, but probably will when I have the cylinders sleeved.

You will also need a head  gasket for the 79 mm bore. Cometic makes nice copper ones that are re-usable.

These are high compression pistons, so they need premium gas. The engine also responds well to anythjing that helps it breath. I built a set of 36 mm carbs from the GS ones and a set of 36 mm bodies from an old GS1100. I have a Hindle large diameter exhaust, and head work.

I have been running the stock rods and crank, with a Dyna rev limiter to keep it below 10,250 rpm. The engine make very good power down low.

I do not have a price yet, but I can easily get more than 4 made up. If you want a pair, I will need a 50% deposit once I have all the details.

[Blueknyt]

hehe, ok, so 555 piston is 79mm , i have one, and the cases are already cut for it. so just need one more piston, but then again, i have sleeves sitting here that are a touch bigger then 79mm, closer to 82mm. i could just have them put into the jugs and find pistons and rings for them. you arent kidding about them pistons being high compression tall deck, with deep valve reliefs. gotta do abit of rebalenceing im sure.


GOD i wish i had the cash for things like this. i would love to make a streetable 550 or even 600cc gs500e its already a ball and a half to outcorner some of these guys around here on the bigger 4cyl bikes, but to pull with em out of the corners for awhile, the looks on their faces through the helmets would be pricless.  well, i need new tires before i can go messing with them again.