"tunk, tunk, tunk, tunk" on idle

[badwithcomputer]

Well i discovered this noise today after coming back from an interview to become a motorcycle safety instructor in my area.

As i parked at the office and let the bike idle down after a fairly spirited 20 minute ride back, i noticed a tunk, tunk, tunk, rhythm coming from the left side of the engine but if i revved the engine past idle it went away completely. Let it fall back down, same thing again. Not a click or a tink, sounded like someone was inside the exhaust pipe with a little hammer.

The valves were adjusted 6,000kms ago. Which is the only thing I would think of that may make that noise. My other thought is a timing chain? Just trying to rule out any rotating parts. Couldn't be the chain or sprockets as the bike was not moving.

also, after 1 year of mandatory advanced training, you are looking at a certified motorcycle safety instructor!

[Kreylyn]

Well i discovered this noise today after coming back from an interview to become a motorcycle safety instructor in my area.

As i parked at the office and let the bike idle down after a fairly spirited 20 minute ride back, i noticed a tunk, tunk, tunk, rhythm coming from the left side of the engine but if i revved the engine past idle it went away completely. Let it fall back down, same thing again. Not a click or a tink, sounded like someone was inside the exhaust pipe with a little hammer.

The valves were adjusted 6,000kms ago. Which is the only thing I would think of that may make that noise. My other thought is a timing chain? Just trying to rule out any rotating parts. Couldn't be the chain or sprockets as the bike was not moving.

also, after 1 year of mandatory advanced training, you are looking at a certified motorcycle safety instructor!

If the cam chain is a little loose, then at lower rpms it can hit. At higher rpms it would tight up a little. I would check your cam chain tensioner spring.

krey

[badwithcomputer]

Man, I really wish the Service Manual was a true PDF rather than .jpgs, would make it a heck of a lot easier to navigate to the pages you want..

[badwithcomputer]

ok well this is weird, It sounds like it coming from the gas tank!?!?! If i hold my ear right to the tank it gets incredibly loud, I went all around the engine and couldn't hear it until i placed my ear right to the tank.

could be possible that it's the float arm? I don't have much gas in the tank probably enough for it just to be touching the bottom tank (passed the red, almost to the E)

[djdaredevil]

Fill her up and check for the noise would be the easiest
way to find out also the cam chain is right under the tank
so you could just be hearing it through the tank

[badwithcomputer]

I'll fill it up this weekend, I've been trying not to ride it as much as possible as my chain is all catty-whompus and i don't want to burn up my transmission bearings but you're right that's probably my best course of action.

[badwithcomputer]

cam chain :/ another thing to add to the list!

[Kreylyn]

cam chain :/ another thing to add to the list!

You measured the cam chain and it's out of spec.... or you verified it's the cam chain making the noise.

More often then not it's the adjuster spring that is worn out, and needs replaced (cheap and simple replacement part).

Krey

[badwithcomputer]

I verified that filling it up made no difference in the noise. I will look into the adjuster spring and whats involved in the replacement process.

Thanks again Krey!

[badwithcomputer]

ok, I've been reading the service manual inside and out and I get the impression that the cam chain tensioner is not adjustable?

I haven't taken it apart yet to look, but i've been reading up on what i need to do.

Krey you said i probably need to replace the spring, would that be because the tensioner is tensioned by the spring and when the spring wears the chain looses is tightness?

I also can't find in the manual where is shows how to replace this spring, only the whole tensioner can any lend a hand there?

I have done a search and came across this:

http://www.600rr.net/vb/showthread.php?t=135386

but didn't really give me the info i needed.

Thanks!

EDIT

with 35,000miles is it time to replace the chain?

[Kreylyn]

ok, I've been reading the service manual inside and out and I get the impression that the cam chain tensioner is not adjustable?

I haven't taken it apart yet to look, but i've been reading up on what i need to do.

Krey you said i probably need to replace the spring, would that be because the tensioner is tensioned by the spring and when the spring wears the chain looses is tightness?

I also can't find in the manual where is shows how to replace this spring, only the whole tensioner can any lend a hand there?

I have done a search and came across this:

http://www.600rr.net/vb/showthread.php?t=135386

but didn't really give me the info i needed.

Thanks!

EDIT

with 35,000miles is it time to replace the chain?

Cam tensioner works by haveing a plunger that will lock into place to prevent it from being depresed. A spring behind it keeps pressure on pushing it out so it locks at the tightest appropriate position as the chain stretches.

If the spring is no longer in spec, it's not pushing hard enough. Take the spring out (one single large bolt and it slides right out) measure it per spec vs the manual.

If out, replace (for a few $).

If you want to measure the cam chain to make sure, you can do that easily if you take the valve cover off. But... I wouldn't think it was needed to replace at this point normally.

Krey

[badwithcomputer]

i ordered one today without even knowing if it's going to fix my problem, but i do like your optimism and for only the cost of a foot long sub, it's worth a shot.

So the procedure is as simple as you listed above? once i replace the spring the cam chain should be tensioned back to stock spec correct? it wont affect the timing or the position of the arm wont be "reset" to the wrong position?

[Rare83Kat]

It would be wise to inspect the tensioner plunger assembly while you're at it, because a weak spring wouldn't on its own cause the can chain to become loose unless the tensioner itself had failed.

That being said However, a quick and positive procedure to make sure the cam chain is tensioned.

1.Remove the right side cover cap to access the bolt to turn the crankshaft with a socket wrench.
2. Pull the tensioner cap bolt and remove the spring.
3. Now stick a small diameter screwdriver into the tensioner assembly and push in on the plunger inside the tensioner by hand with the screwdriver with a couple pounds of force, while at the same time rotating the crankshaft clockwise to slack the backside of the cam chain allowing the tensioner to take up any excess slack.

Important...Listen closely while you're doing the above process for a "click" sound in the tensioner assembly which will tell you you've taken up slack in the chain.
You might even hear (and feel) it click two or three steps on the plunger if your chain was excessively loose.

hth

ps.. if that don't get rid of the ticking noise then you've got other possible issues to look into such as valve clearance adjustment

[badwithcomputer]

hey it's you again! haha thanks for the help in my other thread too!

well i got the old spring out and noticed it's 2 spring wraps shorter than the new one, so I am guessing she has been well worn, I came in for supper and will go out and put the carbs back on and air box and fire it up, if things still aren't right I'll follow your instructions above.

thanks again!

[badwithcomputer]

welp. the noise was gone, and now its back. that didn't last long at all.