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nope, bearings are different, and they don't make one that will allow you to adapt either, been there fought that battle.
 

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I thought I remember Wes said he found a a way around this.
 

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really?? i'd be interested in knowing as well then. I searched for quite some time, and talked to a LOT of people about this. The only way i could see it being done is to make some sort of bushing for the case as the bearing OD's are different.
 

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I have heard of people repairing worn main bearing housings with bronze bushes , i don't see why it wouldn't work to get the imperial bearings into metric housings, alternatively you could could do the same thing with aluminium and carefully tig weld the joint and clean it up with a boring head in a mill.

Probabily just easier to sell the cases you have and buy another set.
 

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it is about somewhere around a 25 thousands difference, the 30 m/m metric bearing is 1971 and up bearing and is the same one used in late model 500's,
The story is it was a cost savings thing done when Triumph's management was taken over by BSA and they proceeded to run the company into the ground. BSA set out to fix everything that was wrong with the 1970 model Triumphs (nothing). So in 1971 BSA gave us the OIF frames and leaf spring trans indexers, conical wheels, metric bearings....thanks BSA

(sorry...had to rant)
 

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Discussion Starter · #8 ·
Thanks guys for the replys, the reason I ask is I'm after a new crank for my triumph and this one came up on a website in New zealand and I thought it might fit, I'll just keep looking, Once again awesome help!!!
 

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I have heard of people repairing worn main bearing housings with bronze bushes , i don't see why it wouldn't work to get the imperial bearings into metric housings, alternatively you could could do the same thing with aluminium and carefully tig weld the joint and clean it up with a boring head in a mill.

Probabily just easier to sell the cases you have and buy another set.
yeah thats the only way i could see doing it. Thats a LOT of work for a questionable fix, we are talking about the crank here afterall.... New cases or crank is def. the way to go. imo.
 

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a 71/72 650 c/c crank is a 2 year only crank. it is technically the same crank as the later T140 crank but the balance factor is different because of the short rods and heavier pistons of the 750's.
In theory you could use the 750 crank with the 650 flywheel but that is uncharted territory as far as balancing goes.
Or you could keep the cases and put a T140 crank, rods, and top end on it, but you need to hog out the cases for the barrels to fit.
Or if you really need a metric 650 crank I'll check and see if I have one.
 
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