Roasted clutch with Z-start?

3 replies to this topic
  • billoyd

Posted December 16, 2003 - 09:15 PM


I was riding down in Baja last weekend on my '02 xr650r. I was running down the middle of Laguna Salada (moist and soft dry lake bed). We ran probably 15 miles at top speed many times the motor pulling hard and lugging when it got too soft. When we got out onto the hard road again, I had cooked my clutch? The bike has about 2000 miles on it. I was wondering if this is normal expected wear and tear? The clutch had been working properly prior to entering the dry lake. Was the power of the motor to much for the clutch to handle a new tire in that goo?
By the way when I got back to camp I had ripped every other center knob off, (clean down to the carcass) on a brand new Dunlop 739at, That gets really old? Any suggestions?

  • qadsan

Posted December 16, 2003 - 09:46 PM


The z-Start should be providing more clamping force than the stock clutch at higher engine RPM, so I'm kind of shocked to hear this. If by chance you were lugging it too much in too high of gear to where there was a lot of clutch slip going on, then things would heat up very quickly and the friction discs would fail much quicker. Try contacting Al Youngwerth to see what he has to say. Is your's setup to lockup quickly and do you have enough of the carbide balls installed? Is your clutch actually fried or are things just worn to the point where the z-Start needs to be reshimmed? Have you measured the friction & drive plate wear yet? I'm sure Al could tell you the minimum speeds you need to maintain in each gear to minimize slip.

I hope there's nothing too serious going on. Make sure to change oil soon enough if you haven't already done so. Also, if you do end up installing new friction discs, make sure to clean your downtube screen for the first two oil changes afterward as it might get clogged with debris from the new clutch.

I heard some of the guys racing the Baja 1000 went through a half dozen or more tires because they were badly chunking. I recall someone saying they measured tire temperatures in excess of 200F when run at higher speeds for a while. Wow, 15 miles at WOT is something I've never done on this bike. That's way kool :)

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  • billoyd

Posted December 16, 2003 - 10:01 PM


I have not pulled the cover off yet. I will work on it tomorrow night. Just wanted to throw this out before I got started? I will do my my measurements first, then pull plates and check wear. I bought all new plates today, just in case! I have all the carbide balls loaded for a stiff engagement. Stiffer the better!!! I will call Al before I get started. He sent me a new top plate(thicker)That I will install as well.

Laguna Salada runs from the Sea of Cortez all the way to the border at the Yuha desert, probably 75 miles!!! You can run it pinned almost the whole way, Very Cool!!! The mexican race came through there on Sat. (Ensenada to San Felipe)

  • Bryinsd

Posted January 07, 2004 - 09:22 PM


You get that auto clutch working right yet? Im ready to buy one , but Im going to let you work out the bugs.That Mex ride we went on was great,right up to the part where I crashed and blacked out for 10 mins. :) Good thing I have a hard head. Lesson # 1 - Respect the BRP for she will hurt you !

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