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View Full Version : 94mm stock piston vs. 99mm JE piston


chad502ex
12-23-2004, 07:42 PM
a picture is worth a thousand more words
86atc250r
12-23-2004, 08:37 PM
Since the piston operates with the wrist pin and rings in place, you really should measure the whole assembly.

Comparing the piston weights alone is not really comparable. As you may be able to see from the picture, the 99mm piston's wrist pin is not nearly as wide - even with the disadvantage of not having a tapered wrist pin it is still much lighter than stock - to the tune of about 50 grams.

All said and done, if you weigh with the wrist pin, circlips and rings in place the 99mm piston assembly is over 70 grams lighter than stock.

A significant difference - you bet... Performance increase? Not really, but it is significantly easier on the rod at higher RPMs.

I haven't weighed stock bore replacement forged pistons, but I imagine the weight loss is even more substantial.
chad502ex
12-23-2004, 09:40 PM
Originally posted by 86atc250r
Since the piston operates with the wrist pin and rings in place, you really should measure the whole assembly.

Comparing the piston weights alone is not really comparable. As you may be able to see from the picture, the 99mm piston's wrist pin is not nearly as wide - even with the disadvantage of not having a tapered wrist pin it is still much lighter than stock - to the tune of about 50 grams.

All said and done, if you weigh with the wrist pin, circlips and rings in place the 99mm piston assembly is over 70 grams lighter than stock.

A significant difference - you bet... Performance increase? Not really, but it is significantly easier on the rod at higher RPMs.

I haven't weighed stock bore replacement forged pistons, but I imagine the weight loss is even more substantial.

thanks for your input.
Shawn H
12-23-2004, 10:56 PM
Do you know what is the weight diffrence on a 97mm piston and the stocker?
chad502ex
12-24-2004, 06:10 AM
Originally posted by snowgasm
Do you know what is the weight diffrence on a 97mm piston and the stocker?

i know the weight of stock now; so, if you call the manufacture of your piston they will tell you the weight of the 97mm- then you'll know the difference.

in my case i wanted to verify that my bigger 99mm ultr-light was indeed lighter than stock. most pistons that are bigger than stock are heavier too!