Author Topic: Suzuki RM125 A/B Crank  (Read 1129 times)

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Offline pmc57

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Suzuki RM125 A/B Crank
« on: July 29, 2010, 09:04:56 pm »
We have a crank we pulled out of a RM125B motor and the crank dimensions don't seem to match up.
Could someone please help with correct sizes.
The crank web diameters are 87mm where the ID of the cases is 93.5mm, another crank we have has a web dia of 91mm. Our feelings are the 87mm dia crank is out of another model ie an A, does anyone know whether an A crank has smaller web diameters compared to the B?

Another question. If the smaller diameter crank was installed in the larger diameter cases (with correct top end), would it affect performance in any way ie 87mm crank dia with 93,5mm case dia?
« Last Edit: July 29, 2010, 09:10:25 pm by pmc57 »

Offline huskibul

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Re: Suzuki RM125 A/B Crank
« Reply #1 on: July 29, 2010, 09:23:51 pm »
  Hi ,the 87mm is out of an "A",the 91 is B/C,and the N/T are 93.70 ,i think the A crank has a little less offset in the pin ,hence  the shorter stroke,50 v 54mm, not sure if it would alter crankcase pressure -enough to effect it anyway ,someone may know?cheers

Offline huskibul

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Re: Suzuki RM125 A/B Crank
« Reply #2 on: July 30, 2010, 08:44:56 am »
   While were on the subject,previously people on the forum mentioned some people fit 125-B cranks/top ends to 125-A cases ,the B crank wont physically fit in the A cases bigger diameter 87mm-A V 91mm B/C, the ID of cases are 89mm-A /93.20mm B/C . the easy answer would be take it off the webs,but the counter    balance holes are only in 2mm from edge! the question is did they mill/turn out the cases(the A cases are  thicker around web) or take a bit off both web and cases ? any input would be greatly appreciated   :)