M25 crank shaft bearings

[Andreas Piepke]

Finding M25 shoulder bearings seems really difficult to say the least. Any advice out there for a source of Steyr or FAG bearings with brass cage? I found:
1) FAG M25-TVP with polyamid cage (from a German supplier). These are rated to only 90 C. One would worry about the temperature stability and resistance against gasoline and oil. Do people have experience with those?
2) M25 bearings of undisclosed make (probably from a Chinese manufacturer) apparently with brass cage (from a British supplier). Is there any experience out there using Chinese bearings?

I understand that at least one of the Chinese manufacturer stoped making those too. Availability of crank bearings may become an important issue for fixing engines.

I would greatly appreciate to hear about your experience before spending money on this!

Thanks

Andreas

P.S.: Yes I did check with Al Buehner.

[Mickey Sergeant]

Most of us  here have been using one piece bearings. Makes it harder to shim cases, but can be done.

[tofriedel]

I wouldn't worry about polyamid cage.  Those were used in new KTM's as early as 1981 and probably before.  I replaced mains (M30)in my 1981 495 and the originals had the polyamid cage as did the new bearings.

Tony

[G Ellis]

I have some that I had made for me. They are slim here in the states. Email me at [email protected]

[Keith Meatyard]

Andreas, I have gotten bearings for these motors and trans from Bartlett Bearing in Birmingham 866 987-1915.  They got me Consolidated M20 and M25 separable race types, as well as some of the odd needle bearings in the trans shafts.  I work with Bartlett daily in my electric motor repair business.  Tell em I sent ya.

Keith Meatyard

[Andreas Piepke]

Thanks Keith! I've contacted them with reference to you.

Andreas

[brian kirby]

Just use modern one piece bearings. Modern Sea Doo watercraft main bearings (Rotax engines) have polyamid cages.

Whatever you do, DO NOT use Chinese bearings on the crank. Wheel bearings and other places are fine for Chinese bearings, but main bearings are a bad idea.

Brian

[ALB]

The problem with the Chinese bearings is that the balls are smaller and the internal race is fatter. When to try to put the case halves together, the balls get pushed out of the groove in the internal race (small balls & small groove). This results in a lot of grief and aggravation.
I wound up with a shipment of these last year and wound up sending them all back. A costly lesson for me with double freight charges and import tariff fees.   STAY AWAY FROM THESE BEARINGS - specify the FAG brand when searching.

Alan Buehner

[BrianTaylor]

If using the one pc bearing  is the process for shimming the crank the same as using the M20,s  .. thks BT

Brian Taylor

[Andreas Piepke]

Got two of the good German made FAG M25 bearings with brass cage:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3342_zps2a4718bb.jpg.html?sort=3&o=1

Here my collection of new FAG bearings for engine and transmission rebuild:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3345_zps58d79312.jpg.html?sort=3&o=0

Thanks for the guidance!

Andreas

[Andreas Piepke]

Hi All,

I am fixing to install the new bearings now. Have a look at the picture below:

http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3531_zpsb3228b19.jpg.html?sort=3&o=0

This is how I found the crank seals installed when dismantling the engine. On the left (clutch) side seal carrier the seal spring points to the outside. On the right (mag) side seal carrier the seal spring points to the inside. Isn't the right side wrong and needs to be assembled the other way around? This sure needs to be uniform.

Thanks in advance!

Andreas

[454MRW]

Check out this thread on crank seal orientation, it seems that the spring always go on the inside toward the crank. Mike
http://pentonusa.org/forum/topic.asp?TOPIC_ID=12246&SearchTerms=crank,seal,placement

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R

[Andreas Piepke]

Thanks, this makes sense.

Andreas

[Keith Meatyard]

Just looked in the Penton repair manual.  Spring (therefore the lip) faces the crank, both seals.

Keith Meatyard

[Andreas Piepke]

I've installed, after pre-heating the case, the crankshaft main bearings and the transmission bearings, all FAG brand:

http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3538_zps446b7777.jpg.html?sort=3&o=1

http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3541_zps215561fe.jpg.html?sort=3&o=0

In the process I've encountered another problem on the transmission side: while the small FAG 6203.C3 fit well, the larger FAG 6205 don't! The larger bearings are both loose. Is there any way to secure those? Are the FAG bearings known to have a loose fit? Needless to say: I don't really want to get a new crank case.

Thanks

Andreas