1.25mm bore question

[Yamyzfrrider]

This question is to anyone that had bored thier cylinder 1.25mm bigger than the standard size on a 125cc engine.

I just realized my bike had been bored 1.25mm bigger than the standard size before I bought it. And I was wondering if any of you that bored your cylinder noticed any difference between the standard size vs. 1.25mm bore size. Was there a big or little difference in power? Any details would be helpful like HP gains, etc.

 

[xerouse]

First off what kind of bike is it? And who did the bore work?
second what cc is it now a 151 or 167. See if you have just the bore and not the stroke. the bike wikk have a lil more power., but where youll notice it if its just the bore that is. Is in tha hit of the bike rather than the pull

 

[Yamyzfrrider]

Its a 1988 Yamaha yz 125cc. I just rebuilt the engine 2 months ago. And according to the Wiseco website the displacement after the 1.25mm bore is a 129cc compared to 123cc. Oh yeah and the bore is 57.25mm compared to the 56mm standard.

 

[xerouse]

Yah i dont think your going to notice any diff. at all. but that also depends on how well you know how to tune it. but as for as the bore youll barly feil it off the bottom end. but with such a small increas your average rider wouldnt be able to tell.