XR650 into CB250

[D O G]

I am currently doing some daydreaming about a potential project, that being a stripped down cafe style CB250 (or really any cheap 250), with a big thumping single in the frame. My current thoughts would be that an XR650 engine would be the go, give plenty of power, be fairly reliable and sound nice to boot.

In short, am I mad? Will the engine even fit in the frame, and will there be horrendous complications with chain line up etc (thinking that since enduro wheels are fairly narrow there shouldn't be too much of a problem with this).

If I am mad, what are accepted decent engine swaps for these sort of bikes?

The idea is to build a track day tool on the cheap, and to be different from all the other guys out there on the ususal stuff.

Clearly it owuld need some significant suspension mods, probably a new front end, or just new internals, again how available are such things? I was thinking that if MZ's can be made to handle very well then surely common 250s could do the same?

Any input appreciated to focus my thoughts!

[NiteMare]

first thing to be answered would be, which model CB250 are you planning to use??

K series, G5, and Wet dream all used a pressed steel spine in thier frames....

i've no idea about the later ones
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it ain't broke...

i ain't fixed it enough

[D O G]

[tatters]

Quite a tall engine on the XR650 unlikely to fit in a little frame.
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Past:NRG50,AF1125(x2),NSR125RR,ZZR250,CX500,VFR400,KR1S,ZZR600(x2),CB400N,YZF1000(x2),KH125,Z200,FX400R,CBR954RR(x2)GPZ500S,GT550,VFR750F(x2),RD350N,XR650R,CBR600F,CB250,KDX250,YZF750R,CRM250,400EXC,KLR650,TTR600RE,DR350S,R100GSPD,RGV250,VMAX1200,DL650,KZ750 Present:G650XC,C12,CRF450X,1190ADV

[virus]

The biggest engine you can get into a CB250RS frame (without major work) is an XL/FT500 (FT was the electric start road going version, much like the CB250RS was to the XL250). To get either of those engines in you either have to chop off the top engine mount, or cut out the spine of the frame a bit and make a custom bracket inside the tube, either way I doubt it will make a high miler before it ruins the frame.


Cheers
John
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[G]