I would like an opinion on a transmission bearing I recently got from a seller. The bearing I needed, that I bought, and was advertised as was/is Yamaha # 93306-20306-00. I got the part # from the Speed and Sport website, so I thought the # should be correct.

As I understand from the tech library the "06203" is the bearing part #, and the existing old bearing is indeed a 6203Z bearing (shielded on one side). This jives with my recollection of the numbering system.

The bearing I got was not a 6203, but a "83483 H I C" bearing, that measures larger OD by 2mm, but same ID of 17mm, thickness 12mm. The box was a Yamaha box with a sticker on it numbered 93306-20306, but I am thinking that a different bearing got put in that box.

Could someone confirm for me that I should have expected a 6203 bearing? If I got the wrong part I think the seller should take it back, but if I ordered the wrong one, then that is on me.

The bike is the '68 DT1 I am rebuilding (on a restoration thread).

All I can say is I agree with your part number analysis. If the original bearing is a 6203 as well, then either a different bearing was put in the box or someone at Yamaha made an error or something.

Doesn't sound like your fault... not sure if someone has an early parts list (printed book type) as those often contained the generic bearing numbers.

Not sure if this helps as only skimming the story at the mo--but, I recall back in the day they increased the OD of the bearing because it was breaking. That would make it a yamaha special only bearing not an over the counter bearing from somewhere like skf bearings. I'm talking the bearing in the case behind the kick idler gear. Ignore me, i'm woffling--reminiscing.

I don't remember if location was mentioned but original being a 6203Z I would guess by the shield it might be the ball bearing behind the clutch? Weren't the bearings Yamaha changed the size on the needle bearings?

Very good point though because sometimes with the supercessions in the parts books it can be tricky if a bearing was changed and you still have the original cases... but again, I think it was the needle bearings that were changed on a couple models?

I've had a wee look over some original parts books .
68 DT1 p/n 93306-20303
69 DT1 B p/n 93306-20303
71 DT1 E p/n 93306-20301
72 DT2 p/n 93306-20306
They all relate to a 6203 bearing , but on the DT2 it is tagged as a 6203 Special .
It does look as if there was a case modification on the 72 model .
I have a copy of a Speed and Sport manual ,printed off a late model micro fishe ,
and that shows the DT2 numbered bearing on 68, 69 , 70 DT1 , which I believe is wrong .
Your cases need an plain 6203 bearing . One of the three DT1 manuals tagged it as Z ,
which is a metal sheild , one side only , but the other two had no such note .

Thank you Mark and Swoop. I grabbed the different part number Swoop listed and found 4 on eBay, 2 just show the Yamaha box with the number tag, one shows a photo but from the back side showing it is a ball-type, no markings, and the last does show a shielded bearing but not a 6203. I did find just plain old 6203Z bearings just by putting that in the search, and that may be how I have to go for this one.

The bearing in question is in the right side case, between the clutch and kick start shaft, Looking at the casting, they would have had to bore out the hole another 2mm to accommodate the larger bearing. Doesn't seem to be a lot of meat there to take, but that is not my area of expertise.

The pics show the case, and where the bearing lives (pen points to the bore). The last pic is of the 'not a 6203 bearing' that supposedly should go there (it won't fit)

Appreciate the feedback guys!




So to end all this, as the "correct" part number bearing will not fit, as it is 2mm larger OD, I have purchased an off the shelf 6203Z shielded bearing, and will use that. Same as what was in there. Yamaha may have upgraded this bearing/case after this one was made, but I cannot do that. Oh well. In all reality, the bike will get used only very lightly while in my hands.