All of the Wiseco pistons are very close to the weight of the stock piston.

You need to run premium, and if you do there are no problems with detonation.

I am aware of 2 forum members who went out on the interstate and rode at sustained 75-80 mph speeds prior to the piston being properly broken in.....and the siezed the piston.  There is also one member who recently had a 97mm sieze when the cylinder was not bored properly - his new 95mm Wiseco is behaving well so far.

You need to keep an operable compression release if you go with a Wiseco.  You may not need it every start.....but once in a while the piston comes to rest on the compression stroke, and the starter cannot get it over TDC without the advantage of some rotational inertia that the compression release provides.  (The compression release only works for 1 or 2 rotations of the crank).

The difference in HP from the 94mm to the 97 mm is only 2-3 HP - you can install the smaller 94mm in the cylinder without boring the cylinder oversize.  (I am running a 95mm and it works great).

The seat of the pants dyno has one thing that is almost as accurate as a genuine dyno... A 10% difference is about the minimum that you can feel.

A simpler method to measure your gains is with one of the 1/4 mile time smartphone apps. Do a before and after run and you have a record of the difference then.

Thanks to all for the good info.  Christof13T, do you have any additional info on the failure?  Was it a seizure, wrist pin, etc.?  I'm curious why you state that the 97mm is only 1mm larger than stock.  Isn't the stock bore 94mm?  That would make the 97mm overbore a 3mm increase.

DragBikeMike wrote on 03/25/18 at 11:50:09:


The cause of the factory build failure is still undetermined.
Suzuki said it was the result of a "Cold Lock"... but the failure occurred at 80mph going uphill after already been riding for a good hour...

The piston has evidence of potentially being a bad casting... but without access to a qc lab i can't prove it.

The 2nd failure was on the 97mm rebuild.
Something screwy happened with the boring process that left the cylinder egged, tapered, and oversized. After the failure and subsequent teardown... a circumferencial crack was discovred in the bore on the exhaust side right at about 12 O'clock... 2" from the bottom of the bore. The fellow that did the cylinder work put in a new sleeve from L.A. Sleeve and bored it to fit the 95mm wiseco and carbide coated the cylinder.

My issues of not being able to break 80mph seem to be cured. I had a spare carb laying around, so I cleaned the heck out of it and set it up for middle of the road jetting. I'm sure the other carb just has a clog somewhere..