After market brake lever for 2008 YZ450

I purchased a new brake lever for my 2008 YZ450, aftermarket, took the bike out and had the front brake sieze. I took the lever off and brake went back to normal, put the lever on, all seemed ok then the brake seized again. Had to remove the lever to finish the ride. Any ideas?

First, be sure you have the correct brake lever. The '08 takes the same lever as the '07-'08 YZ250F, and is different than the lever that fits other, older YZF models back to 2001.

Second, the details escape me at the moment, but a search might turn it up. There is a cap between the lever and master cylinder piston that causes a fit problem with some aftermarket levers. It can only go in one way, or it doesn't match the curve of the lever, or something like that.

Either way, the problem is that when you install the lever, the piston is being pushed down the M/C bore to the point where the fill/return port is being closed off. This traps the brake fluid in the system, and does not allow it to back up into the reservoir when it expands as it heats up. That locks the brake. Removing the lever lets the piston return all the way, and opens the port, returning things to normal.

I am using an MSR for the 2008. So, when I install, if the piston is even barely pushin the M/C piston that this problem may occur? There really is no adjustments to make so it would have to be a faulty lever. Like an idiot I already threw my old lever away so I cannot compare.

It can occur if the piston is pushed in too far as the lever is installed, yes. It should have some small preload on it to keep it from rattling around, but not much. Does the lever travel from rest to brake applied seem shorter than stock? Does the brake seem OK when you start out but get tighter as it gets hotter? If yes, then that's almost certainly your problem.

One way to check is to see if you can insert a screwdriver between the brake pads and push the caliper piston back in fairly easily. If you can, the port is open. If not, you found your problem, especially if you can remove the lever and then push the pads back. (remember that when you move the pads back, you'll have no brake until you pump the pads back out against the rotor)

You can correct it by filing the little knob on the lever that engages the M/C piston down a little, so that it doesn't push the piston in so far.

I had the same issue when i broke my break lever, you must be sure to keep the bolt loose and tighten the bolt...better said loose bolt with a tight nut, when i did the install this way I have been trouble free for months.

On a side note, it is very upsetting while on the MX track and your front wheel decides to lock up :thumbsup: :thumbsup: :thumbsup:

I have had at least 4 bikes that locked the front brake with aftermarket front brake levers. I have made calls to our parts supplier and the lever manufacturer and they say if you use the correct lever it will work. As soon as I talked to them I had another one lock up so all I use/sell now are Yamaha levers. Yamaha just lowered the price on them but they are still about $25. I guess that is cheap compared to locking up your front wheel on the track.

:thumbsup: Get the new Renthal unbreakable levers and let me know how they work:busted:

Thanks, DPW.

That was the thread I was trying to recall. :thumbsup:

Thanks to all!!!

Thanks, DPW.

That was the thread I was trying to recall. :thumbsup:

I put a MSR lever on the wife's '08 250F and ran into the exact problem...luckily it happened early in the day when she was just cruising around the track.

Does this apply to ASV levers as well? Or just regular after market levers?

I have used ASV. I think their ok. A better lever is Sunline lever. I never have had a problem with them. I know alot of people in the motorcycle biz and they swear by them. I agree with Grayracer. It appears he knows his s@*&

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