Help.Chain slapping

[dimk]

Hi,my bike is a 620s ie '04 and when two up i hear a sound like chain slapping fro mthe lower right side of the bike especially when opening the throttle.Chain and sprockets are new and properly tightened.Could it be the chain guide worn?Bike has 12000miles

[uclabiker06]

Thats a tuff one.  Make sure your chain is adjusted properly. I would say put it on a rear stand and turn it on but you don't want to do that w/ a Duc b/c the power is delivered in pulses so the chain will indeed slap around but it shouldn't do that w/ you on the bike.

[BK_856er]

Lower right side as in the side opposite the chain?

Two up?  That will tend to tighten the chain even more.  Not sure what measurement you used for tension, but your chain should still have good deflection/slack with you sitting on the bike and the bike supporting your weight.  You don't want the chain binding up, ever.

New sprockets?  Did you install the front sprocket in the correct orientation?  On some bikes it can go on two ways, and only one way will align it correctly with the rear sprocket and chain guide.

BK

[dimk]

Thanks for the replies.The noise is coming from the chain area.The chain and sprockets installation was done by my mechanic not me, so i assume it was done correctly .i can't replicate the noise when riding alone.only when 2 up.I think i will change the chain guides on the swingarm and see what happens...

[pennyrobber]

It would be nice if there was a way to film the chain while riding two up or even have a passenger watch the chain to see if there was something obvious going on. (disclaimer: the poster is not recommending acrobatic passenger behavior and is not responsible for lost passengers)

[motoyoyo]

A new chain will stretch a bit after a few hundred miles.  You should recheck the chain adjustment.  The best way to be sure it is perfect is to jack the bike up on a lift and remove the rear shock.  Then move the rear wheel up and down to find the tightest point on the swingarm arc.  Adjust so that the chain is only slightly slack at this point.  Sounds like a hassle but is pretty easy if you have a motorcycle/atv floor jack.  This is the only way to be sure you got the chain adjusted correctly.  Anything else is just a guess.

[uclabiker06]

Why don't you just tell the mechanic who did the chain?  See what he says.

[BK_856er]

Why don't you just tell the mechanic who did the chain?  See what he says.

Yes, definitely ask your shop about it.  New chain guides will not solve your problem unless they are totally shagged, and that is not too common - have a look before you order.  First order of business is for you to learn how to measure and/or evaluate the chain tension.  Even if you don't want to actually adjust it yourself, as a rider you really should be checking the tension routinely.  This is a great opportunity to start doing that.

BK

[dimk]

It's going to my mechanic asap.Thanks for the replies