Vintage Dirt Bike Q & A

Check me on this, I cant take out enough slack in the clutch cable to keep the clutch from slipping. Taken up all the slack with the external adjusters, same with the internal adjuster.

What am I missing? Need new clutch plates? .cable?

The less slack you have in the cable, the more likely your clutch is to slip. I'd set the internal adjuster & actuator arm as per the service manual (if you don't, the throw-out bearing may have a short life), and I set up my clutch-lever cable adjuster so there's little lever resistance until it's pulled in about 1/3 to 1/2. For me, it's far more important to be able to control clutch engagement while my fingers are still near the grip, than it is to have it disengage the instant I touch the lever.

Service manual below, if you don't already have it:

http://honda-elsinore.alp-sys.com/manua ... 5mr175.pdf

Be sure to use a motorcycle-specific oil in the gearbox, rated for use with wet clutches.

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

Ray

I have tried adjusting the clutch as per the service manual and taking out the slack in the cable. After doing both of these, I still have 1/2" of slack at the clutch lever.

Time for new clutch plates?

OK, sorry - got it backwards (happens a lot these days).

It could be many things - worn/missing plates, missing throw-out or basket washers, loose hub nut, spring issues, stretched/incorrect cable and/or adjusters, damaged side cover or actuator, lever, etc. How many miles are on the bike, and has anything clutch-related been replaced to your knowledge?

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

The bike has 2000 miles on it. To the best of my knowledge it is all original, down to the tires. I've not pulled the clutch cover yet to inspect the plates, etc. I guess that is the next place to start.
When I got the bike, I noticed the was 1/2" play cable at the lever end, as in there was 1/2" freeplay before it would start to pull the cable. Noticed the lever adjustor was maxed. Figured it needed an external adjustment down on the case, nope that one was maxed too. Tried backing those off and doing the clutch adjustment as per the manual through the adjustor window. When set to spec, rod all then way in then backed out half turn, the free play got worse. As in it wouldn't begin to actuate the clutch till the lever was now 1/4 from the grip.

The cable is free and runs smoothly through it's housing.

Does this mean the clutch is slipping during riding? If so, the clutch cover needs to come off, especially since there's way too much cable slack and the internal adjuster is set correctly.

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

Ray,

That's what I am thinking, though I am not sure if it is slipping. If there is too much slack in the cable, wouldn't the problem be its not disengaging the clutch enough, is that what you mean by slipping?

I've always operated on the basis that you adjust the cable so there is an 1/8-1/4" free play between the handle bar clutch lever and the lever mount. So when pulling the lever into the bars, it starts to disengages the clutch after that 1/8-1/4" or full engages the clutch when the lever moves away from the bars and when it reaches that 1/8-1/4" point.

My clutch doesn't begin to disengage until the lever is almost pulled all the way back to the handle bars. There is no more external adjustment on the clutch cable and the internal clutch adjustment as set through the window in the engine case is at factory spec.

By "clutch slipping", I mean the clutch plates are not clamped together as a unit and instead are sliding against each other, as if you're holding the clutch lever in a bit. A slipping clutch will still slip even with a properly-adjusted cable, or no cable at all. It may also slip with a cable that's adjusted way too tight, but that's not the problem you have. You won't be able to truly determine a slipping clutch unless the engine's on and in gear; does this bike run?

Is your cable the correct one for the bike? If your cable's too long, you'll never be able to adjust it correctly with the stock adjusters. With the cable off the bike, the engine end of the center cable should protrude no more than 3.1" from the end of the adjuster on the cable.

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

Ray
Yes, the bike runs fine and I have ridden it around. When I start it and shift into gear, no grinding in the tranny so it is disengaging the clutch enough to shift.

When I let the clutch lever out to engage the clutch, it engages right as the lever leaves the contact with the handlebar. Then there is 1/2-1" of free play. Normally, I would adjust the tension using the adjustor at the lever perch or on the clutch case. However, those adjustments are maxed out.

I'm not sure if the cable is original to the bike. Perhaps it is not the correct cable and to long. Any idea on how long the OEM clutch cable should be?

IJ

Try measuring the protruding cable end as I suggested earlier, and see what you get. I don't know what length the '77 MR175 cable is, Honda used a different one that year.

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

Ray
Did as you suggested, removed cable and measured the free end,
4.1-4.2"

So it woe appear to be too long

I have a kit to make up a new cable. Thoughts on an OAL, would be greatly appreciated.
IJ

IJ,

The 22870-373-000 / 22870-373-405 cable for the '75-'76 MR175 has the following dimensions:

47.38" overall length
44.0" sheath length
2.75" cable travel

I believe the 22870-373-780 cable for the '77 MR175 is identical except for vendor, as all 3 years of MR175 have the exact same clutch setup. The '74-'78 CR125M clutch cable (p/n 22870-360-010) will also work fine, but the overall & sheath lengths are both 1.6" shorter (cable travel is the same) since Honda ran the MR cable down the left side of the frame, and the CR down the right.

The cable below is pretty good - I'm currently using one of these clutch cables as a front brake cable on my 'MC175' bike w/Yamaha front brake:

http://www.terrycable.com/Clutch-cable- ... p_185.html

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 ordered the CR125 cable you recommended. I'll let you know when I receive it and have it installed.
Thanks again for the help.
IJ