Info - Tohatsu and Wiseco Pistons
Topic: What should You know about them?
Oh my . . . The main thing to know is that both are "taller" than wetbike pistons.
The Wiseco's are forged pistons - and they require a more careful setup. Most importantly, they require a proper warmup - EVERY TIME OUT.
The 86 mm pistons have the following things worth noting:
a. They are HEAVY - and will probably last forever
b. They are a 3-ring design. Probably not needed, but they do seal really well
c. They are a cast design so they can be setup pretty close like a Suzuki piston.
d. They are ungodly expensive. And the rings are ultra-expensive.
How Do I Make Either One Work?
Getting the proper clearance for the piston style is critical.
Also, since the pistons are taller, the port timing will be off. If you don't correct this, then you can run into the situation where you have a big bore motor that doesn't make much more power than stock.
If you are gonna run either of these pistons, plan on having the port timing corrected. You'll need to have all of the ports "raised". The exact amount is the difference between the suzuki piston height and the Wiseco/Tohatsu's. Port Timing and/or modification is covered in-depth in another article.
What Else Should I Know?
BIG SNAFU to be avoided. These pistons are a machined differently where the connecting rod sits. That is they are wider at the top than Suzuki pistons. So, you'll have to come up with different washers up top to get the proper end play (and avoid excessive gaps). These rods are top-guided, you have to do your homework to get the proper fit. ProX and Hot Rods are 2 sources of these hardened thrust washers.
Your motor is gonna run a tad warmer. Be sure you have all of the water passages cleared of any corrosion and/or casting flash. Might even consider adding a "pisser" to the cyl head to aid cooling and removal of trapped air.
Copyright 2011 Capt'n Obveeus