370 big bore?

[3wheelerkrazy85]

About how much HP can be expected ? Is this reliable ?
What are the pros and cons?

[RIDE-RED 250r]

I'll answer all 3 of your questions with one reply.... Depends on your build. It varies depending on the quality of the parts used, specifics of the setup, and the workmanship of the shop/mechanic putting it all together.

But in general, any descent 370 should be in the 60-70hp range. But remember, races aren't won on the dyno.

As far as I am aware, you can't go any bigger than 344cc on a stock crank. Bigger than that gets you into stroker crank territory. And make darn sure your bottom end and transmission are in good shape to handle the extra power before spending the coin on a big bore setup.

My advice is to do some searching around here and other forums. There is an abundance of info on different setups that should help shed some light on some of your questions.

Also, try talking to companies like ESR, BDT, CT, and others that do big bore setups for 250r's.

I am running an ESR 78mm cyl on a stock crank (344cc) along with all of the usual supporting mods and I am very happy with it. She really rips!

[3wheelerkrazy85]

Thank you very much!! I'll do some investigating !

[RIDE-RED 250r]

No problem. And BTW, welcome to 3WW.