crankshaft swop for xj650 from xj750

Hi Does anyone know if the xj 650 crank can be replaced with a 750 crank without any hassles or modifications , If so, do you order the bearings for the 750 or the 650, but I would presume they would be the same if it was a straight swop. I live in S.A. and there are very few if any spares for the 650 but a lot more for the 750,
I,m referring to the shaft drive models 1981 to 83 (or later if they could swop and fit)
Shipping from USA to S.A. is prohibitive.

 

I'm going to guess it can't be done, or at least isn't a straight swap; the 750 has 56.4mm stroke, 650 has 52.4mm.

It would be possible to swap an entire 750 engine in though...

 

tHX , however AT THE RISK OF BEING STUPID I WOULD USE THE ORIGINAL CONRODS THE BARREL HAS BEEN REBORED AND NEW PISTONS , RINGS ETC , JUST WAITING TO BE FITTED ONCE CRANK IS SORTED. MY MAIN CONCERN OBVIOUSLY IS THE SIZE OF THE CRANK IE THE 5 MAIN AND 4 BIG END JOURNALS?? I'm JUST A diy NOT A MECHANIC AND GOT THE BIKE AS A PROJECT, BUT DIDNT EXPECT CRANKSHAFT TO BE WORN. THEY LIKE HENS TEETH HERE IN S.A.

 

Not if you're going to use the original connecting rods. And realistically not, anyway.

Because of the way Yamaha "blueprinted" the bearing shells to the journals with their bloody silly "color coding" whereby they don't share ANY actual dimensions, there's virtually no way you'd be able to properly match the crank to the block, considering the way the whole thing works. You could probably get it together and get it running, but you'd be riding around on a grenade waiting for a place to go off.

But stroke isn't a factor of con rod length, it's crank throw. So I don't see how it could work to begin with.

 

Thx.
Guess i'll have to throw that thought out the window, and keep looking.
ciouw
Mervyn

 

Get a 750 motor - - trust me, you'll love it.
(get the carbs too, or re-jet)