Vintage Dirt Bike Q & A

I am considering doing an engine rebuild on my MR175 and I was wondering what exactly I need to do this. I know that I need a head gasket, a base gasket, and a center case gasket at least. I have no problem getting gaskets, I have the part numbers for those, but my problem is with the engine bearings and seals. Does anyone sell a complete kit with bearings and seals at a reasonable price. Also, does anyone know the part numbers for all the parts I need, seals and bearings? Also, any tips or tricks on rebuilding elsinore engines, I have experience on rebuilding 4 stroke singles and twins, just wondering if there is anything different besides the obvious.

Thanks for the help.

Theres a couple of people on ebay that sell bearing and gasket kits, don't know how reliable they are. If you can do a 4 stroke....2 stroke should be a breeze. I'm gettting ready to do a 80 cr250 in a couple months, new crank rod and the whole shootin' match.

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Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007

Once you get it apart you should be able to to see the numbers on the bearings any good bearing supplier can get them for you. Also do yourself a favor get a micro fitch of your bike, you can use a reader at your library, it lists bearing numbers and seal sizes.Bearing suppliers can often get seals, but you can always get them from Honda if they cannot supply them. Gary

Heres what I use for microfiche. This link should be for 1976 MR175

http://www.mrcycles.com/fiche_section_d ... &fveh=3515

I've bought two bearing kits off the eBay seller. Complete kit with new seals was only ~$60. When I asked for a kit for a DT360, they said I would have to supply part numbers. I suspect a MR175 would need the same.

I use that same website for all my microfiches(MR Cycles). Its nice to have it online and be able to print it out on your printer. I think that i will order whatever i can from the honda dealer because i got the hookup and get the parts at dealer price, not retail. I guess my real question is that is it possible to still order these parts from the dealer, or are they discontinued? Has anyone ordered their parts from their honda dealer lately, your information would be appreciated.

Anyone have firsthand experience with these "inexpensive" bearings that are sold on Ebay??

I think that bearings and seals are made to a standard size and therefore since Honda just outsourced them rather than having them made to their specs, you will not have any trouble getting them from your dealer

http://www.hbico.com/index.htm

Made in China.

The bearings in my MT sounded like someone on metal wheeled roller skates going down a steep hill. My CR's bearings were just a bit worse.

I don't ride enough to ever wear out anything. I am getting used to an engine that is relatively quiet. Saying they are better then worn out bearings isn't much but that is all I have.

Main bearings in my bikes usually have a "C3" designation........

Its got something to do with a clearance or speed rating, not sure .

I bought 2 bikes with freshly overhauled engines that had loose cranks after about 2 hours racing.
Problem was caused by bearing part # being correct but not "C3" rating.

Also, some main bearings outer races are more rounded on ends/corners.
The "squarer" profile of generic bearings can obstruct the oil lube hole to the main bearings.........be carefull.

Premium bearings are cheap insurance to a long engine life.

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'84 Honda CR500
'84 CR125
'85 KX125
'83 IT490
'82 Maico 490
'80 YZ465
'75 Husky CR360 GP Mikkola
'75 CR250
'72 DT2MX
'91 XR200

You can still get bearings & seals through your local Honda Dealer for your MR. You may have to order them but you can get them!

Good luck.

I think I might still have a set of rings for that bike, I bought a lot of 80 NOS Honda sets awhile back and those MR sets went fast and they were begging for more. Everyone told me they are obsolete and very hard to find.

Vin