Chain slack- Final verdict?

After a buddy of mine destroyed his rear wheel when the sprocket broke off his 426, I wanna find out what the final verdict on the chain slack we should be running on the YZ400/426. I have been running 2 inches and at times I look at my bike and think, "Damn that's alot of slack!". So what's the verdict gentlemen?


99 YZ400

PS: Rock on Tim Ferry...

The min in the book is 1.6. If you set this as a tight 1.6, you'll have problems. Anything over this and you should fine.

To be safe, get comfortable with your settings and the slack available at full extension (disconnect the shock and raise swing arm).

Hope that helps.


make sure you loctite the tapered heads on the 6 sprocket bolts! If you dont the torque of the engine will rip the sprocket off. It almost happened to me! My sprocket was hanging on by 2 bolts :) now it is just fine for about 4 months and I also havent adjusted my chain in 4 months! I guess I found the sweet spot @ around 2.1 inches!



I get my kicks on a 2001' YZ426!

Friendswood, TX

The 3 finger method has worked for me for years w/o any mechanical Chain or sprocket failures

I use the 1 3/4" approach maybe a little more.

I tried going 1.6 and ended up hitting a HUGE g-out and ripping the sprocket forward on the left and the right side back???

Not quite sure 100% how the axle came loose but fought it for about 35 miles of touching the breaks and tweeking the bike one way and snap the throttle ----the bike twitched the other way! spooky!!!Got back to the truck at the finish and the axle seemed to be fine but had been pulled to an angle.

Since then I don't do the 1.6" anymore.

I figure a little too much is a lot better than the jarring of the "chain stop suspension" and wearing out $130 worth of chain/sprockets!

I tried several settings and found that anything less than ~1.9" would result in the chain 'stretching' back out to ~2.1" after 1 ride. Once I tried setting the slack close to the minimum stock setting and almost lost the rear hub and sprocket: all the bolts were loose and the sprocket actually rattled on the hub. Now I use 2" as a baseline and will let the slack increase up to 2.25" before readjusting.

Sounds like 2.1 inches to me. Thanks alot for all the replies.


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