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97 Foreman 400cc with 450cc cylinder?

6311 Views 2 Replies 3 Participants Last post by  JBGill06
First of all, your forums are great, Happy to be a part of em'.

I have a 1997 400 foreman 4x4, just got it, smokes really bad, seems to be more so if going down a slope using engine as brake. It still seems to make decent power, maybe its mostly the valve seals.

I am sure i read it somewhere in these forums,(cant find it for the life of me now) that you can put the cylinder out of a 450cc onto the 400cc

Found this: Honda TRX450 Foreman Engine Motor Top Rebuild Kit and Machining Service

Will this fit without much hassle?
Can some one tell me the stock compression ratio of the 2 engines? I think the 400 is 8.5:1...not positive.

I know 50cc on its own is not going to make much difference, but if it has a higher compression ratio as well, i think it will be noticeable.

Would 11:1 be fine on premium pump gas? if not im pretty confident 10.5:1 will be. Any real world input here would be great.

Im looking to get the most bang from my buck, like most i suppose.

I was thinking a mild increase in tire size, say 25 inch tall and 1inch wider front and rear. I dont want to sack to much bottom end power by going to tall. I have no interest in gear reduction.

Thanks guys
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