Vintage Dirt Bike Q & A

Hello Everyone. I'm new here and just picked up a 1975 MR175 yesterday. This forum is amazing and I've found tons of great info from searching already.

The bike is a little rough and has the wrong color tank for the year among other issues. It's not running but only missing a couple of parts so hopefully I'll have it up shortly. One of those parts is the left side crankcase stator cover. Does anyone know if the cover for a MT125 would fit it or have a lead a decent used one for sale? There are a few on Ebay but they are either pretty rough or really expensive. I think I'll need it to get the timing set so I'm going to need it a little sooner than I originally thought.

Here's a pic of what I'm starting with...assuming I got it to upload properly.

I'm 99% sure an MT125 ignition cover will fit the MR175, as every MR cover I've seen has the same neutral-switch section as the MT one. I don't know about timing marks, though. If the MR marks are changed on the flywheel instead of the cover, the MT cover might work fine.

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

Thanks Ray. I really appreciate the input. I'll give it a shot.

I got it running today so it's moving much faster than expected. The bike is a little Frankenstein with an aftermarket Mikuni carb and some rather creative solutions for attaching things including "custom" engine hangers on the front.

I can't find a serial number on the engine so I'm not positive what I'm working with here. The frame is '75 and the tank is from a '76 I think.

I tried the Uni NU4012 air filter off my MT250 and it didn't fit as I hoped it would. Does anyone have a suggestion of another option?

Sometimes the serial number area of the cases (directly behind the ignition cable, above the sprocket) can be taken out by a thrown chain, and if the cases have been replaced, this area will be blank. If the frame number starts with 100 it's a '75, 200 is '76, and 210 is '77.

The guy below sells MR175 air filters, but they're not always listed. If you contact him through eBay he may be able to help you out. I've been using these for years, they work great and survive repeated cleanings with no damage:

http://www.ebay.com/itm/Honda-MR175-197 ... 7675.l2557

You might want to measure the Mikuni's venturi, directly adjacent to the slide. If it's bigger than 30mm and the motor's stock, the carb won't work as well as it should at full throttle unless the intake manifold, cylinder intake, and intake port are opened up.

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

Thanks again Ray. I ordered the filter from Fred. He's not on Ebay now and might not be going back. If anyone is looking for an air filter for a MR175 (he probably has others) you can contact him directly.

fredanddeb@actrix.co.nz

He was amazingly helpful and quick to reply despite being across the globe from me.

Also the bike has clearly taken a few hits over the years so I'm sure that part of the case was replaced. The frame is definitely a '75. Assuming I measured correctly, we're good on the carb size. Thanks again for all of your input. It's a tremendous help.

Paul

Paul,

Thanks for Fred's E-mail address. It will be a good thing to have, especially if he'll no longer be active on eBay.

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