Axle Blocks are Not Correct?

I was adjusting the chain on my bike (08 YZ 125), set both axle blocks to be on the same 'notch' on both sides. Took it for a ride, then later I was cleaning the bike and noticed mis-alignment between the rear sprocket and the countershaft sprocket. I took measurements from the swingarm bolt to the axle on both sides and they're off by 1/4"! Probably should have done this first when I adjusted the chain, but I simply didn't notice. Never thought it'd be a problem as it never was on my old bikes. Luckily there was no damage, and my rear sprocket/chain seem unharmed.

Is this common with this generation of YZ 125's?

Edited by JRod4928

I've always heard the axle block marks shouldn't be trusted on any dirt or street bike, but I've never done the measurement like you've done to confirm.

I've always heard the axle block marks shouldn't be trusted on any dirt or street bike, but I've never done the measurement like you've done to confirm.

I'll keep that in mind from now on based on my experience.

I should note that as a 2nd check, I put a 1.5 foot straight edge on the rear sprocket to see how it lined up with the chain guard that rests on top of the swingarm. The alignment was off by about 1/4" over that length as well.

Once I set the axle blocks based on the swingarm pivot/axle measurements, the rear sprocket was aligned perfectly with the countershaft sprocket using the 'straight edge check'. The chain appeared to be straight from front to back sprocket as well.

If there's some error - and there usually is - I do the straight edge thing and then write "+1" , "-1". etc. on the swing arm with a marking pen. Then I don't have to mess with the straight edge every time OR remember what the error was.

I measure mine everytime, never trusted the lines. That being said I've never checked alignment either, but now I kind of want to.

Edited by poldies4

It is not the axle blocks that are wrong but the marks on the swingarm.

This has been raised before and was noted that the guy from yamaha that puts the marks on the swingarm is the same guy that put the transmission

oil check hole in the wrong place on the 250. :naughty:

My 250 has after market axle blocks and the alignment was still wrong.

I have remarked both my 125 and 250 swingarms.

My mates 250 was spot on so not all are wrong.

Mine are spot on ( all three bikes ) but I still check with straight edge. Misalignment robs horsepower.

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