single clack sound
 

Hi guys,

I installed a 351cc kit a couple of months back now on my 06 but due to time restraints haven’t really put that many KLM’s on it yet. I’ve really only put about 300klms as It is still breaking in I haven’t been that hard on it but the last couple of rides I have started opening it up a bit more.

Any way I have noticed an audible single “clack” sound when opening up from ½ throttle to WOT coming from the motor. It’s not overly loud but loud enough to hear. It seems to only happen in the higher RPM range and only when rapidly opening the throttle to WOT. At idle and just crusing around it can’t be heard.

I am thinking that it’s the cam chain but the fact that it’s only a single “clack” and not a series of “clacks” that it could be something else.

I did the valves just after the Big Bore installation and they are all in clearance and I quadruple checked the timing before putting it back together so I know that’s all good.

I have done a number of searches and am still leaning towards the cam chain and it makes sense to me that it could bet the cam chain as I had to loosen it to shim the valves so the adjuster might not have fully taken in all the slack and it might still need to work in one or two more clicks.

Just wondering your thoughts?

I don't know, neil, that doesn't really sound like the cam chain issue from the description. You had the tensioner out if I understand correctly when you did the valves. I'm assuming you "unloaded" the tensioner for reinstallation, so it probably can't be too tight. If it was even one tooth too loose, I'd say you'd hear that classic rpm-related cam chain noise that's like a somewhat muted "knack, knack, knack, knack"...but not one notable, louder sound like you're mentioning.

For some peace of mind, I'd pull the valve cover off and see if the KACR device is intact and functioning properly. While in there, see if anything else looks odd.

I notice a clack noise once in a while on my bike as well. usually when sharply nailing the throttle.

Are you guys sure it's not some kind of chain snatch action?

i can almost gauraunte you that its your chain on your sprockets. my yz450 would do that. just deal with it. i thought it was the motor to but its a popular thing to have happen

I used to hear a similar sound on mine when I had the stock exhaust....almost like detonation,don't hear here it now with the TBR's:D

Thanks for the replies, I’ve never heard about chain slap... ill check it out and try and pin point the area the noise is coming from.

Just dont tighten the chain too much, you dont want it getting tight when the suspension is at its max compressed. ;) Two fingers on the top between the chain and the guide.

i do 3 but i guess i have small fingers lol. i had to adjust my chain all the time with 2 fingers so i figured that was to tight.

Good to know I was never really sure on how tight to have it. I have had a chain come off mid turn leaning the bike down before and that didn't turn out so well for me or the bike. Think I might run it a little tight now because of paranoia