Split the cases to replace the crank bearings and noticed first gear has been slightly rubbing on the case. Per the parts diagram all of the washers and clips are there. What could be the issue?

Only thing i can think of is that at some stage its been running for a bit with the sprocket nut undone--until the sprocket fell off--Hmm.

In the other half of the case there is a bearing with a snap ring and retainer plate...

On some models, that bearing needs to have an "extra round" radius to seat all the way into the case... not on the snap ring side... the side that goes into the case first.

Without the large radius (special bearing), it won't seat all the way into the case and could cause the issue you're seeing...

On Partzilla, looks like it's supposed to be a 6305XN... The X designates the larger radius on the back side of the bearing... Someone might have used the more common 6305N

Arrow points to radius on edge of bearing I'm talking about.




Had the same problem on a DT175... but it rubbed HARD. When I looked close I could see snap ring and retainer plate were not completely flush to case. Just a tiny gap but it was enough. Correct bearing fixed the issue.

I could tell the cases had been split before, so I will check that bearing.

Guess what I found. The bearing in the case is a 6305N. Ordered one today. Thank you!

Make sure you get the X bearing... I've ordered from Yamaha (Partzilla) and while the sticker had the right number, the bearing in the box was a standard one without the X. I ordered the same part from a different Yamaha part source and it was correct... different brand bearing and had the X.

Yamaha obviously doesn't make bearings so what I think happened is a purchaser or somebody at Yamaha bought the wrong type. It also could be that part is also spec'd for a newer bike that doesn't require the radius and so they superseded the bearing to one without the radius... not caring or knowing about the older models. This was on a 175... not 250... just wanted to warn that because it came from Yamaha doesn't mean it's always correct.

That picture from Partzilla and the problem you're having tells me you need the "X" version.

I like RMATVMC for my oem parts. They carry the 6305xn and have fast shipping.

Good going Mr. MarkT on the bearing info.

I love RMATV too!

Glad they had the right bearing... I think that's where I reordered my 175 bearing from and got the right one. Wrong one from Partzilla came in a bearing manufacturer box with a Yamaha part number sticker. Correct bearing came in a Yamaha box like yours did.

You should be able to see the difference in radius with parts side-by-side.

I am rebuilding a dt 250, and it can be such a pain to shift. I am pretty sure I have the non x bearing as I just order what was already in the case. Is it possible that this wrong bearing would cause hard shifting?