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Bike lurching/grinding forward occasionally

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Anyone experience thier bike lurch/grind forward quickly occasionally?  A bit scary when it happens because I'll have to pull in the clutch quickly to stop it, and then release it the second time to get a smooth take off.  I checked the clutch plates and they all look perfect!  One of the bolts on the pressure plate was a bit tighter then the other three, someone said that might be the cause ??  Any thoughts? 

It's a KTM EXC 450 , 2009

Thanks! 

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Could be a notched-out basket, though that's not typically as big a deal for the KTMs as it is other brands.  Pretty easy to look at and get to, and you can usually just file the notches down instead of replacing the part.

Might also be a main transmission shaft bearing.  Mine got "buzzy" when the bearing under the clutch pushrod let go.

One side's under the clutch slave cyl., that pops off easy and would be worth looking at.

Other side's under the clutch, so you'll need to pull the clutch cover off and rattle off the nut holding the basket/inner hub in to get to that bearing.

If it is a trans shaft brg, you will have to split the case to replace that. 

 

First sign something was wrong (filters were messy too):

2012-09-29_13-34-14_246-L.jpg

 

I definitely ran that bike longer than I should have... :devil:  (the outer race was a real mofo to punch out of the case)

12%20-%201-L.jpg

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Took a look at the firts picture....Not had one of those engines in bits myself, but most clutch baskets are aluminium alloy and therefore not magnetic, then I scrolled down and saw the second picture....I guess I should have scrolled before thinking too hard on it...

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Thanks SnowMule for the awesome info and pics!  I did notice the clutch basket had some light notches in just one spot, next time I have it opened up I'll shave it down and see what happens.  Then go from there. 

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You can probably pull the cover off and get to it without taking off the clutch nut and inner hub ... you'd want to be real careful about cleaning up and getting all the filings/grit out before you reassembled.  It'd definitely show you if you needed to do it or not.

Rattle the nut off, clean the nut/threads, slide off the inner hub and basket... file the notches down, clean the basket, and put everything back together... wouldn't have to worry about grit in the oil doing it that way.

 

IMG_20140803_152206395-L.jpg

 

You're looking for grooves where the tabs on the fiber disks engage the basket. 

DSC06465-L.jpg

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