Vintage Dirt Bike Q & A

I have two MR175 crankshafts with too much slop in them. I have been looking for the bearing, pin, etc. but can't find any. Anyone know where to find a rebuild kit, or if another cranshaft's pin, etc will work?

MR175 crank rebuilds are kind of a nightmare, as the rods are practically nonexistant (if the rod feels sloppy surely its big end surface is at least partially to blame, although a new bearing and crankpin might improve things a lot). My friend is presently working with Crank Works to see if it's possible to hone the rod end for an oversize bearing and/or pin, or use an early RD350 rod, which I believe is 1mm longer ctr-ctr but otherwise very similar. It's actually easier to find a NOS MR175 crank than a rod.

Here are the bearing substitutions I have; the KA3 and KS3 parts are for the '81-'83 CR125R. Some are still available OEM:

91004-373-006 / 91004-373-300 / 91004-KA3-003 / 91004-KA3-004 / 91004-KS3-901
91005-373-006 / 91005-KA3-003 / 91005-KA3-004 / 91005-KS3-901
91006-373-006 / 91006-373-300 / 91006-KA3-003 / 91006-KA3-004

I've managed to find all three crankpins, using eBay and Google.

13381-373-300 / 13381-373-310 (2 groove)
13382-373-300 (1 groove)
13383-373-300 (no groove)

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric