wiseco pro-lite clearances

[m in sc]

need direct experiences here. the pro lites seem to come in metric overbore sizes as opposed to the 'regular' wiseco pistons ( in .02", .04", etc)

Now, according to wiseco, directly off their site, it states this:


"05.    There is no piston to wall clearance on the box label, what is the piston to wall clearance for my application?
A.    
Wiseco Powersports pistons are designed for optimal piston to wall clearance for the specific bore size of your engine. For example, your 125cc dirt bike engine is 54mm bore, the Wiseco piston is designed just for that bore size, and does not require any specific adjustments to fit properly."


do the pro-lites -really- drop right in? vs the 'regular' wisecos? i have no direct experience.  Just weighing my options here. 

[Alain2]

Wiseco Pro-lite pistons clear 0.003".

[1976RD400C]

Same thing here. I use them in my modified 400. It says on the box .003" clearance but as I recall for a air cooled engine you may want to add just a bit more, like .0032-.0035. After quite a bit of use (2 years ?) I checked them and noticed new rings were needed. Did that and a couple years later checked them and my clearance was just about .005". Most all the wear was on the piston so I just replaced the pistons and the clearance was back to about .004". I remember Chuck has all the specs on pistons and they are sized to fit a bore that is exactly what it is supposed to be, as in 64mm. The piston measures .003" under 64mm. I thought most pistons are sized that way. Wossners are, and they are just a touch bigger than the ProLites making for about .0005" less clearance. No complaints here. I have beat this pistons and they work real good.

[m in sc]

good to know, thanks guys. kind of what i suspected.  I just ran across that and was kind of confusing.

[Dvsrd]

0.075 to 0.100 mm clearance. They must be quite noisy when cold. Would forged pistons luke these Wisecos and Wossner require more careful warmup than cast?

[Yamaha 179]

The Yamaha OEM pistons are manufactured and sold to bore size, e.g, a RZ/Banshee  350 first oversize piston 2GU-11635-00 measured 64.24mm by micrometer.  The Vertex Banshee 22568075 third oversize piston 64.75mm actually measured 64.70mm.  The Wiseco Suzuki RM125 2126CS 54.00mm forged piston measured 53.95mm.
The Wiseco box specifices a clearance of .0020" or .051mm. 

I believe all OEM pistons are manufactured to actual bore size and all the aftermarket pistons I have seen are sold undersize by the clearance the manufacturer recommends.  That is why I always send pistons with cylinders when I want bore jobs done and I specify the clearance I want, not necessarily what the piston manufacturer recommends.
Lyn Garland 

[sav0r]

I always just assumed the difference was that pistons designed for a bore size were basically for plated cylinders. You just buy a piston and pop it in.

For anybody that is going to bore, you would measure your piston and bore to fit.

[rodneya]

0.075 to 0.100 mm clearance. They must be quite noisy when cold. Would forged pistons luke these Wisecos and Wossner require more careful warmup than cast?

Definitely. Hammering it while cold can easily result in a cold seize (four corner seize)

[1976RD400C]

They are kinda loud when you start it, but cast pistons make noise too. After is warms up it's not too bad. I have the CHT gauges that let you know when it's warmed up and ready to go.

[m in sc]

MMMM..  my wiseco pistoned bike is wayyyy louder than any cast piston bikes i have. (rd to rd). and the lightweights topend was a chuck q topend so you know its right.

[1976RD400C]

MMMM..  my wiseco pistoned bike is wayyyy louder than any cast piston bikes i have. (rd to rd). and the lightweights topend was a chuck q topend so you know its right.

I guess you're right. When I didn't have those rubber dampers in the cylinder fins it bothered me and I put them in and it helped. I guess I'm used to it.

[Czakky]

Between my forged piston (5k mile) RD cylinders, solid tappet guzzi and my Ducati dry clutch I'm used to weird noises. The lower end of my 63' c100 is a bit troubling though...

[m in sc]

YOU KNOW, the noise itself doesn't bother me. however, if you can hear it tapping, its wearing. that's just physics. that small gap increase gives the piston a fraction of a second to accelerate the skirt movement and 'tap'. also, the expansion characteristics of the materials are not worth any benefit otherwise perceived on a 2 stroke street motor IMHO. I never liked that and wont run wiseco' unless i have no other choice. (for a street bike).  I get it on a race bike, 100%.  personal preference.  I've had some spectacular motor blow ups.. but never ripped a wristpin out of a piston. except, ironically, on a forged piston on my big bore grom.  . 

[Czakky]

Well said. The wear part is what I imagine anyway...

[Hawaii-Mike]

My triples with Wossners remain quiet after thousands of miles.  I'm for Wossners in all my 2-strokes.