I've been running a Primary Drive 12t front for some time. When I installed it, the OEM 13t slipped off and then I slipped on the 12t with zero effort. Then I torqued the CS nut to 69ft lbs per instructions and the previous CS nut locking indents aligned correctly on the shaft. Simple...

This weekend after 7100 miles, I decided to install a new chain and sprockets. I purchased a GYTR 13t #GYT-75503-13-00 which is supposed to fit our WR250s.

Well, the install was just the opposite from the PD 12t install. The GYTR required a press fit to get onto the shaft. I never really whacked it hard to get it on, but it it did take some effort. I'm fairly confident that it's seated.

Then I re-torqued the nut and 69ft pounds no longer lined up the indents with the shaft. It's was about a 1/3 turn short.

Anyway, what I'm worried about is that perhaps the sprocket is too thick or perhaps it's not seated correctly. And that that may lead to premature wear on the chain...or something else.

Can you tell from looking at the pictures? Too me it doesn't look like the CS is completely seated.

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Beeing a thinkin man, I would pull the chain off and see if I could get a light and maybe a guage feeler behind the sprocket. Sounds impossible, but sounds like it would be worth the effort.

Can you take the sprocket off? Perhaps it has some sort of side specific mount?

More importantly did you get the right one? Yamaha dealers have been notorius for ordering the wrong parts for the wr... If this is a YZ sprocket instead of a YZF sprocket you'll have a problem - they look almost the same but they're not.

Good luck

Thanks for replying.

Being a thinkin man myself...with overthinking tendencies, last night I measured all 3 sprockets mounted. Measuring from the case. They were all within a 1/2 mm of each other, which is within my measuring margin of error capabilities.

It required a slide hammer to remove, which fortunately I had. A tool that I purchased for a project about 20 years ago and haven't used since. :)

The packaging label is the correct number. It didn't occur to me to check the sprocket itself for any numbers stamped on it and the sprocket is now mounted on the bike. I might pull it again to check the back side to verify the part number...

I like your idea of the feeler gauge. I'll try that too.

I was hoping someone that's installed a GYTR sprocket would chime in with their experience. It looked to be machined properly. I couldn't find anything that would make it hang. I just don't think the fit should be so tight...

I've put on a couple of aftermarket front sprockets on and they just slide right into place. I also tried one that was for a WR-F; that one didn't fit...it wouldn't even begin to go in place. Not sure what's up with your sprocket. I thought they would either fit or not.

Definitely check the part number itself if it's stamped. I usually mount sprockets with the stamp out - perhaps the sprocket grooves are machined to only go on that way? Either way, if it's that tight I wouldn't put any serious torque on it. Damage to the shaft would be worse.

I was hoping someone would chime up too since I was considering buying one...

I went to my local dealer last night hoping to pickup another GYT-75503-13 to see if they are all tight or just mine. They didn't have any in stock and I didn't feel like ordering another one...I decided to get a Renthal instead. 420-520-13GP fits like a glove.

I tried flipping the GYTR over and still no go.

I also checked the numbers on the GYTR sprocket and they seem correct. It's stamped 503 13.

Is mine defective or all of them like this? I guess we won't know unless someone else that has purchased the same sprocket posts.

Thanks for the input.

L.J.

I just put a GYTR 13T on mine, slipped right on with some light persuasion.