G1 big bore kits??
 

Well I found this surfing for G1 parts on ebay. Seems to me this would cause some overheating issues but thought id share with the group and see what they thought.

https://www.ebay.com/itm/Yamaha-G1-2...cAAOSw6hBcyRbs

Re: G1 big bore kits??
 

That's awesome!

Re: G1 big bore kits??
 

Should make some G 1 owners happy

Re: G1 big bore kits??
 

What do you think about boring it out that far? Do you think overheating would be an issue?

Im asking questions. The ad states they buy cores, so I asked what the kit would cost with a core sent in. I may pull the trigger.

Re: G1 big bore kits??
 

Well, that is a tough one to answer.... They did make similar snowmobile motors with bigger bore, but they were also operated exclusively in freezing temps.

Re: G1 big bore kits??
 

They also make dirt bikes with an even bigger bore, no cooling fan and fins often covered in mud ? P.S. In 2016 when I built Suzi with the 440 FC snowmobile engine capped off with a HD cart muffler some naysayers predicted over heating and fried pistons and rings. So far even running her hard on 90 + degrees days it hasn't happened.

Re: G1 big bore kits??
 

When I hear back from him on the cylinder I'll probably be a test mule

Re: G1 big bore kits??
 

Ray has a point. Assuming that is an aluminum cylinder, heavily finned, I see in the pic the forced air cooling on a G1 should be fine. As long as the additional bore doesn't adversely affect transfer port shape, height, etc. it should be a nice boost in performance.

From what I can see it looks like there is a lot of cylinder thickness there to withstand 2mm.

Re: G1 big bore kits??
 

It looks to be amodified YZ250 piston

Re: G1 big bore kits??
 

At $230 or so that is hardly a kings ransom for any quality top end kit