Vintage Dirt Bike Q & A

I purchased the MR new in 1976 and have moved a number of times and always brought her with me.
She has 1,600 miles on the clock, mostly off road, but still have the head light and tail light in tact.
Am in the process of changing fluids, is synthetic the way to go for front forks, transmission oil?
The front lower forks have some corrosion spots, how is the best way to remove the marks?
After 35 years is it recommended to replace the rear shocks and if so what is the best replacement?
Have gained lots of good info just lurking on this forum, thanks to all.

Richard,

I use synthetic ATF in my forks, it seems to work fine - I may try 10W or 15W fork oil next time, though. Definitely do NOT use synthetic oil in the transmission! I ruined a new set of clutch plates with Mobil 1 once, and now I use conventional motorcycle-grade 10W-40 (Bel-Ray EXL) exclusively, with no problems. The clutch is still going strong with 4,000+ miles on it.

I was looking at Works Performance Gasser or Dirt Tracker shocks, but ended up rebuilding the stock shocks with the help of a member of this site (thanks, Coll !). The stockers work fine for what I do, but I sometimes wonder what the WP's would be like.

I use a fine-grit sanding sponge to polish my fork sliders, since the original finish is long gone. It might work well for removing corrosion, too. I also used it to smooth pitting on the steel tubes, running a large bolt through the bottom into a 1/2" drill and spinning the tubes slowly on the bench.

Ray

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

Thanks Ray, You are the MR 175 Guru. I appreciate your input.
I plan to follow your recommendations and let you know how it goes.

ray,
this does not depend on synthetic or mineral.
when you use a car engineoil that´s not designed for gears and clutch lurication then it´s no wonder something fails.

_________________
80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

Understood. My advice was specific to the Honda MR175. I use synthetic and semi-synthetic oils in my RM and YZ, but will not chance using either with the undersized, weak MR175 clutch.


Also understood. Not everyone has a high level of knowledge regarding motorcycle wet-clutch lubricant requirements. Four years ago, when I ruined my clutch, I certainly did not - but I learned the hard way. I automatically assume that when someone asks which oil to use in their MR175 transmission, they may not, either.

From my original post, which I still stand by:

..."now I use conventional motorcycle-grade 10W-40 (Bel-Ray EXL) exclusively, with no problems."

I normally try to refrain from mentioning any lubricants in my posts - now I remember why.

Ray

P.S. I found out yesterday that a clutch I recently replaced for a friend has been ruined by the non-synthetic automotive oil he put in it. Another one bites the dust!

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

My air filter element fell apart in my hands when I took the seat off to inspect the air filter.
I believe it was Ray (thank you Ray) who mentioned Fred in New Zealand, well after about a week and a half the new Unifilter from Australia came in. Perfect fit and really nice element. I highly recommend ordering from Fred, the part number is NU 4026.
Richard
Eastern Shore of Maryland