Vintage Dirt Bike Q & A

Nate,

Having 4 MR175's, I think you may be polishing a pig. After everything you will have put into this bike, you would be better served finding an old CR. At least then, It will be worth 3-5K, rather than $500 - $1,500.

That said, it is good you cracked the case. Having new seals are important. You don't want to be sucking in air, or even oil through a bad seal.

If you can, what every you can convert to CR is better. I believe Ray likes to use the CR gears. MR parts are getting real hard to find.

Ray is right on about the CR ignition. They aren't that expensive, but they make a big difference. Bear in mind that you will lose your lights with the CR ignition.

Matt,

I agree about the CR parts - ideally, you'd want an MR motor in a CR frame, like my 2nd bike. I've been meaning to post an update on it, but just haven't gotten around to it yet. A lot of changes were made in the last two years. The other bike (MR175) runs great too though - the CR ignition really changed everything, before that it was fairly pig-like. I'm now running a gutted MT125 pipe, engmod2t porting, 175 psi compression, a 29mm carb, and a '77 MR175 gearbox on the MR, and engmod pipe/porting, 30mm carb, 190psi, and hybrid MT/MR tranny on the MR/CR, which is wicked fast now that the jetting's finally dialed in (CR ignitions on both). I never tried the CR gearbox, though I probably will in the reed motor I'm starting on this winter.

I try never to think about resale - too depressing.

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