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Central Illinois, IL
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Vertex, Namura or Wiseco. Cast or forged. Been reading all I can find on pros/cons of them and see benefits from both but really, what’s the general consensus guys?
TIA.
TIA.
ty (in advance)
The Shop
When my son was racing RM85's, I found the OEM ones to be super consistent on sizing, easy to find, and reliable enough given our change regimen (ring every 5 hours, piston every 10). I had Millenium re-do the coating and they sized it for the OEM pistons. Worked great.
Forged is better if you want to really stretch the limits of piston replacement, as they are much less likely to shatter if you keep them in so long cracks begin to form.
Forged pistons are good, but if you go that route you need to make sure you, or who ever rides the bike knows that it needs to be warmed up well before going WFO. Or it could potentially cold seize.
I saw a seized Namura piston and ring setting on a parts counter recently and examined it closely. Exhaust port side was properly scored and ring was impressively captured within the ring groove!
Once again, thank you to all who contributed with opinions.
T.
If you like to have overextended maintenance schedules, probably shouldn't get the squish reduced. Carbon build up along with a worn crank and bearings can result in the piston smacking the head due to excessive play in the bearings from being old. If you do a good job of maintaining it, you'll likely have no issues and will simply enjoy the added performance.
51* out today and I rode it on the road a bit. It stayed very cool temp wise in the scooter’s cooling system so I did not crank it, all the while trying to be quiet and not pi?? off the neighbors. It was loaded up by the time I got back!
Thanks much.
On our KTM 85's I have always ran Vertex(OEM) & usually ran Wiseco on the YZ85's we had & CR125 mainly due to they have specific pistons that the bikes used. I really don't think you are going to see a massive difference in any quality brand. We run 20hrs usually in the 85's and have never had a piston related failure no matter what brand (except when a buddy tried running a Namura). The whole "warming up" thing has kind of gone away with the advent of plated cylinders. You don't have the big steel sleeve expanding slower and causing an issue.
I set squish, timing and deck height on almost every rebuild. Each smal detail in itself might not make a big difference but added up they do.................
thanks much (in advance)
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