Thread: Pro-X piston fitment
07-31-2007, 03:23 PM #1
Pro-X piston fitment
Picked up the cylinders from the local machine shop. He said that each cylinder is in great shape and within half a thousandth. The bore in each was 84.07mm.
I think I'm going to go with the Pro-X pistons, I've done some research and it looks like the magic clearance number for them is about 0.005 to 0.006 inches.
On the web for Pro-X it says the STD piston part# 01.2514.000 is 83.91mm, so with my bore being 84.07mm that gives 0.16mm which is 0.0063 inches which I think is pretty close?
Yes or no?
07-31-2007, 07:10 PM #2
07-31-2007, 07:15 PM #3
07-31-2007, 08:36 PM #4
Sounds like to big of clearence to me. WFO might have a little more detail on that. I ran .0038 on the OEM pistons and just a little over .004 on the Pro-X. Most people use the Pro-X and I belive is the same manufacturer that makes them for Yamaha.
07-31-2007, 08:50 PM #5
Thanks for the input Duke. I had read two different articles for the ProX's. One said to go about .004 like you are saying and the other said to go around .005 - .006
I have been stuck in the middle ever since. The std size is out of stock at the warehouse anyways so it looks like I am going to have to go with a 84.25 anyways...
07-31-2007, 09:00 PM #6
.005" for Pro x .007" for Wiseco sounds about right to me.
Only way is to measure the piston first then bore the cylinders to size.
3 new pistons will not all measure the same size they must be matched to each cylinder.
07-31-2007, 09:00 PM #7
if you were running wiseco's before the bore sounds right. why not run them and skip the rebore expense all that is needed is a little warm up before WOT
07-31-2007, 09:05 PM #8
The new Wiseco's are .005 smaller than the required bore, so that's 0.13mm. So for STD wiseco (84mm bore), my clearance would be 0.13mm + (84.07mm bore - 84mm) = 0.20mm which is 0.0079" clearance. So is that too much also?
Last edited by bainer1290; 07-31-2007 at 09:16 PM.
08-01-2007, 11:01 AM #9
hahaha well here's the latest news...
Pro-X is sold out at the warehouse of pretty much every piston for the GP 1200, so I can't get them. The local dealer can get me WSM's in .25 over, but I don't really want to go with them...
The option still exists for me to go with the Wiseco's again, but I don't really want to go that route. Looks liek I'm screwed until the stock comes in for Pro-X's which isn't going to be until next spring!
08-01-2007, 11:19 AM #10
What size pistons do you want I went through this looking for 84.5mm prox
Got one at boats.net.
I did email Prox and I might be able to help you.
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