A forum for owners of Yamaha TTR250 trail and enduro bikes!

Jeff B · Senior Member

New Sprag Clutch Assembly on Ebay

ttr steve · Super Guru

Not sure about the company but Rich on here put an aftermarket one in and it disintegrated causing a lot of damage, let's hope yours doesn't do the same.

It would be great if it last as they are expensive from Yamaha.

Let us know how you get on.

ttr steve · Super Guru

Read all about it here

https://ttr250.activeboard.com/t64076126/after-market-chinese-sprag-clutch/

Jeff B · Senior Member

There are 2 types of sprags I've seen. The cheap one that blew apart is a different design than the OEM design. The Frontier sprag is identical to our OEM design.

ttr steve · Super Guru

Jeff

I mean this in a nice way, you are our test Guinea pig

Full report when fitted and some miles on will be appreciate by all.

Jeff B · Senior Member

No problem Steve. smile

I am going to install it on a spare motor I am refurbishing. Then I'll test it. May be awhile, but I'll post reports as I make progress.

Rossyboys · Veteran Member

How is the sprag Clutch holding out many miles and or starts on it

Thanks Grahame

Jeff B · Senior Member

Hi Grahame.

I installed this sprag on my recent street rebuild and it only has about about 100 starts on it along with about 200 miles. Fitment was spot on and snug. Some cheap sprags are too tight and will not slip like they are supposed to while the engine is running causing premature wear and failure of sprag and starter gears. Sofar, it has performed exactly the same as my stock Yamaha sprags. I'll keep the site posted of any failure.

Rossyboys · Veteran Member

Thanks Jeff

be interesting to hear from other members that have fitted replacement Sprag Clutch, I note that the after market one you fittedd was near exact as the Yamaha factory?

thanks grahame

Jeff B · Senior Member

Yes. You can't identify the difference between the Yamaha and the Frontier (Taiwan) sprag in both appearance, materials, or performance. The Frontier sprag comes with the gear race that it slides on which is a good thing because the old gear race usually gets damaged and worn by the old sprag.

Jeff B · Senior Member

Update

I had to tear down the engine after 1000km due to a crank bearing case sleeve failure. This gave me an opportunity to check on the sprag and gear wear.

Crank bearing case failure_20210823_7.jpg

I'm very pleased with its performance. I'll be putting it back in service.

I agree that most of the cheap Chinese sprags are junk. But this Taiwanese sprag from Frontier Motors was a little over half of the cost of the Yamaha sprag and gear assembly.

tom13 · Senior Member

Good news, Jeff. Thanks.

TTRfan · Super Guru

Thanks for the feedback Jeff - most appreciated biggrin