If the bearing feels ok to spin now it'll only get tighter when in the case--case compressing the outer ring. Be good to know if it says C3 on the bearing as sounds like it needs one--or a C4.

Used a bearing splitter/puller and got the bearing off with no problem to the resized LH journal  - which measures barely under 25mm as mentioned.  Now I could read the bearing's hidden side:  "Nachi 6205" (with no other marking) and on inner ring "NC".  Could  that may mean "CN" clearance...which is tighter than C3 or C4?  I got this bearing with the double seal from a smaller vintage 2 stroke MC website and will probably ask about the choice with my shaft.  Meanwhile I ordered what is specd as a C4 bearing and seal from Partzilla.
Regards,
Joe M

Thanks for the update. Look forward to some good news.

Suffix NC usually denotes normal clearance.  C3 and C4 are of greater internal clearance for the reasons already given, plus some limited self aligning capability.

Other suffixes you may encounter are.

Z and ZZ where one Z denotes a tin dust shield on oǹe side only and ZZ has both sides shielded.

RS and 2RS.  Same as above only fitted with true rubber faced grease seals.

Some of the other bearing suffix numbers you might come across are "N" which denotes a snap ring groove.

A tricky one that many miss is the transmission output bearing on some years/models is an "NX2".  Again, N is snap ring.  The "X2" denotes a larger chamfer on the outer edge of the bearing.  (Some models had an "X1", same thing just less extra chamfer)

If you use one without the "X2" the sprocket side output shaft bearing may not press into the case all the way.  Sometimes this is not an issue, sometimes it will cause the trans to be stiff and not turn freely. It can cause output shaft gear to rub on and dig into clutch side case half.  Sometimes it will cause shifting issues. 

You can see the NX2 in the bearing pic at the link below from Partzilla for the later DT175/DT125.  Hard to find NX2 from bearing supply, usually need to buy from Yamaha.

www.partzilla.com/product/yamaha/93306-30411-00

Unfortunately don't have best to report.  Ordered a 41 dollar ($US) bearing from Partzilla (while noting in their website description B6205"C4".  The Yamaha boxed part arrived with a Koyo "6205  21-14  08" bearing inside.  Partzilla's Tech Help is ignorant about internal bearing clearances, and I can't tell on my own what this bearing is.  Can anyone else decode this part?
Thanks, Joe M

What is stamped on the bearing itself?

6205  21-14  08
It is a Koyo bearing inside a Yamaha box.  Maybe the Yamaha p/n accurately correlates whats in the box but the bearing is not stamped C4 (or anything besides th above), while Partzilla describes it C4 suffix.
www.partzilla.com/catalog/yamaha/motorcy...70/ct1b/crank-piston
Very frustrating and Partizlla tech help does not even understand what any of this means....even after 3 exchanges asking the person to confer with co-workers or leadership.
I still don't even know what the other numbers mean to the right of "6205".
Thanks for any knowledge.
Joe M


 

I’ve ordered the 6205 C4 bearings and others from a bearing supplier in the past (Simply Bearings), I’m in the UK. I was able to select the brand I wanted, I think it was about a quarter of the cost your bearing. If your unsure of the bearing they’ve supplied Send it back and order from a bearing supplier.
Parts list for the bike will have bearing code and clearance.
Just my opinion, hope you get it all back together

Here's a link to Koyo bearing nomenclature.  See page 3.

jtkmarketing.s3.amazonaws.com/filer_publ...menclature_guide.pdf

Numbers you see are probably date code.

Sometimes clearance code C3 or C4 is stamped on edge of inner race.  Check both sides of bearing though markings are usually on one side.

I'd return the one you got to partzilla and go to a bearing supply as suggested.

I've had good luck several times with All Balls # 24-1073.  Currently about $40 shipped on ebay.  You get both crank bearings and two OEM quality double-lip crank seals.  The last set I bought had Koyo bearings with C3 or C4 clearance bearings...  can't remember. 

24-1073 kit will fit all the Yamaha Enduros 175's from 69-81.  They could change their part sources so can't guarantee they still supply the same parts in kit.  The three or four I've used were great quality every time.