cbr400rr engine into cbr250rr

[DUBDUB]

Old gsxr250 and impulse 400 frames are the same. I dropped a 400 into my 250 frame with only having to grind the 2 mid engine mounts off

[roadracingoldfart]

It all comes down to what motor / frame models you have.
NC23 will go into some 250 frames but an NC 29 wont go into any as far as i can work out. (mounts are all completely differant)
NC 29s are a slower and heavier bike anyhow and almost none of it will interchange with an NC 23.
Choose carefully for an easy conversion or choose badly with a gas torch and a mig welder .
Cheers Paul.

[HDTboy]

Personally I'd be leaving the 250 as a 250, those things are worth stupid money, and you'd just be pissing it away by putting a 400 motor into it. Having owned a 250RR and a 400RR, there's not that big a jump in the performance.
Why not just get the 400 running? Then you'll have two bikes.

[Chrislost]

im sure a 250 with 400 engine would fetch a pretty penny to some "bulletproof" earner

[roadracingoldfart]

Personally I'd be leaving the 250 as a 250, those things are worth stupid money, and you'd just be pissing it away by putting a 400 motor into it. Having owned a 250RR and a 400RR, there's not that big a jump in the performance.
Why not just get the 400 running? Then you'll have two bikes.

The only reason you say that Gav is that your 400 was rather slow lol.
Us faster 400's would say that there is a BIG jump in performance.
Now where is that 600 motor for the 400 frame ???? 85 BHP anyone !!!

[HDTboy]

The only reason you say that Gav is that your 400 was rather slow

That was true. I got it running on 4 after the weekend you blew me away, it was still pretty average. My 250 was a quick one though.