aftermarket pistons
what is available

How big do you want to go?

Suzuki sells 0.5mm & 1mm over size as stock replacements
J&E can custom make any size

74mm = 487cc (stock)
75mm = 500cc
77mm = 527cc
79mm = 555cc (largest possible with stock sleeves)

hey dgyver, have you ran all those sizes, and what happened to 76 and 78?  what kind of power jumps are we looking at?   at what point are we looking at upgrading cams carbs and exaust?  and at what point whould the head benifet the most from being reworked?

I have the run stock 74mm, 75mm and currently have 79mm installed. Just never seen the other size pistons that are not listed. Bob B runs 77mm in his.

The stock muffer is very restrictive. Letting more air flow through the motor is always a good thing, but requires more fuel.

With the stock motor bike ran good but was lacking. I added cams and the 75's at the same time. The 79's are installed but have not run them on the track yet.

Having the head milled does not gain much without high compression pistons.

On the other heads, I polished the exhaust ports but only removed the casting ridges in the intake ports. Leaving the intake post a little rough aids in the turbulance of mixing the gas & air.

Necking the valves will help with the flow as well.

I have not had the bike on a dyno so I do not have any numbers. Next time at Jennings, I will be able to see the difference with the 79's by the change in my lap times.

have you had any problems with the bearings wearing with the larger pistons? stock wrist pins? and whare do you get the rings from?  with a larger piston how close to square does that make the motor? and how did it affect your redline?  as far as preformance whare did it make the largest difference?

Do not know what the extra wear will be on the motor. Have not run it enough to find out. But since it is a race bike I am not really that concerned.

Using stock wrist pins but wish I could find ones that are about 1/8" longer. I got the rings for the 79's from Wiseco.

The valves float a little beyond 12,5 now. This is because of heavier valve springs.

Torque is going to be the biggest improvement.

ok, so whare did you get the valve springs from?  what about oversized valves? aftermarket vaves?  running up to 12,5 have you had any  probems with the cam chain?  any more vibration probems with the larger pistons?

The springs are available from Megacycle.

Running stock valves.

Still using the stock cam chain tensioner but want a manual one. Trying to find out which one from APE is the same. I know one of the GSXR's will fit.

No problems with any additional vibrations. The bike is normally run above 8k rpms continuously.

cooling probems?  aftermarket oilpumps- any commets?

At WOT, I do not have cooling problems but then I am not in stop & go traffic.

I have been looking at installing an oil cooler though.