Knocking sound, Please help me diagnose.

[rachtak]

My FZ6 has ~15k miles. Recently, the night after a 350mi ride, I noticed a strange knocking sound coming out of the front end of the bike. I've taken it to a mechanic, but he can't figure out what it is without opening up the bike.

My observations:
Description of noise: it sounds like pebbles knocking against the plastic fender above the front wheel. They are not loud, but can be felt slightly in the handlebars.
Location: Sounds like its coming from the front end of the bike
Frequency: rate of 3-5 knocks/second. Occurs in the 2500-45000rpm range. I can replicate the noise dependably if I engine brake hard or accelerate hard.

Misc:
-If I baby the clutch, the occurrences of the knocking are significantly lessened. However, normal and aggressive acceleration/deceleration creates knocking.
-Knocks do not occur when the bike is on the center stand and revved in neutral
-Knocks still occur when I disengage the clutch at ~20mph and coast to a stop at at light
-I cleaned and lubed the chain yesterday and I cannot tell if that has reduced the occurrences of the knocks or not.
UPDATE 4/4/2013: I had the chain and sprockets replaced but the sound still persists.

Just by searching the forums, I suspect that it could be that the chain/sprockets are in need of replacing. However, the mechanic I went to said that my chain looked good (no tight spots, no slapping, aligned, etc). He suggested that something in the clutch basket could be loose.

Since I can't stand the "sit and wait until it gets worse" prognosis. I'd like a second opinion. Has anyone ever encountered something like this? And is it more likely a chain/sprocket problem?

 

[tyler2011]

I'm wondering if the chain isn't worn or has a bunch of crud by the front sprocket. Often times the front sprocket will be more work than the back. There is a little plastic cover (just above left foot peg, just in front of the frame) that has 3 hex key bolts that covers the front sprocket. It also collects a lot of crud back there which can run down by the oil filter. The cover can be removed and slid out from behind the shift linkage WITHOUT removing the linkage, just finagle it a certain way and it pops out.

How is the chain slack? Is the upper chain guide/slider (on top of swingarm behind the frame member) worn?

You may also try rotating the tire by hand on the center stand and watch the chain while this cover is off to see if it is catching or a link is bound.

 

[dangtienanh]

I have had that numerous times on my bike too when I did aggressive engine braking. I suspected it was the tranny but asked around only to hear that was no problem. And so it was, no problem at all. The next day I rode the bike, the noise was gone.

Another time when I had that ticking noise was when I used Mobil 87 gas. When I switched to BP Premium it's also gone.

 

[Gelvatron]

steering head bearings? do the routine check:cheer:

 

[norcalwelder]

Check your oil level, too high and too low can cause some weird noises. I have noticed a ticking sound like you described and replaced my timing chain, guides, and tensioner, but nothing really ever got rid of the problem. Changing my oil level made it go away, but then it came back.

 

[iSteve]

Could just be unburned fuel in the header burning off or maybe ping from real low octane.

 

[rachtak]

@ a number of people who've mentioned fuel rating: I started using 87 Octane on the 350-mile ride recently from 89...I can't make the connection to how that would make the noise though...

 

[TownsendsFJR1300]

If you can narrow down the area would be very helpful.

You mentioned both the front end, fender area, then the engine.


If you could, put the bike on the centerstand, get the front wheel off the ground (I use a sizzor jack under the header(it won't hurt it). Gently push/pull on the front wheel looking to move the forks (we're now checking the steering head bearings) up and down. There should be NO movement/binding with the forks. If there's any play, they need adjustment or replacement. If their loose, the fork triple assembly will literally MOVE back and forth with acceleration, decelerationcausing/feeling some major clunking.

While its still up, spin the front wheel itself checking for any looseness/roughness, etc. If your able, pull the wheel itself and check the wheel bearings spinning them by hand, again checking for looseness/ binding etc. It also may be easier to pull/push on the forks with the wheel removed as well.

If there's a new noise from the engine, a screwdriver with the tip on the block, handle to your ear will help pinpoint the specific area.

Can you get the noise recorded while stationary and post it?


FYI,
http://www.600riders.com/forum/gara...82-handlebar-vibrating-when-hard-braking.html

 

[rachtak]

If you can narrow down the area would be very helpful.

You mentioned both the front end, fender area, then the engine.


If you could, put the bike on the centerstand, get the front wheel off the ground (I use a sizzor jack under the header(it won't hurt it). Gently push/pull on the front wheel looking to move the forks (we're now checking the steering head bearings) up and down. There should be NO movement/binding with the forks. If there's any play, they need adjustment or replacement. If their loose, the fork triple assembly will literally MOVE back and forth with acceleration, decelerationcausing/feeling some major clunking.

While its still up, spin the front wheel itself checking for any looseness/roughness, etc. If your able, pull the wheel itself and check the wheel bearings spinning them by hand, again checking for looseness/ binding etc. It also may be easier to pull/push on the forks with the wheel removed as well.


FYI,
http://www.600riders.com/forum/gara...82-handlebar-vibrating-when-hard-braking.html

When I went to the mechanic, he did the exact same thing (except I held the back tire grounded to the floor). I trust his experience in testing the components that you mentioned, so I think that they can be ruled out...

I will try to see if I can replicate the sound, but I am very busy these days. Thanks for all of your help and patience!

 

[rachtak]

Sorry, for not replying lately; been really busy. I can't replicate the sound while stationary.

Convinced that it was a problem with the chain/sprocket, I dished out $250 to get new ones installed. Unfortunately, the sound still persists.

It is most prominent when engine breaking. Again, it sounds like pebbles are knocking against the front fender and I can feel the "knocks" in the handlebar (but not footpegs).

 

[TownsendsFJR1300]

Sorry, for not replying lately; been really busy. I can't replicate the sound while stationary.

Convinced that it was a problem with the chain/sprocket, I dished out $250 to get new ones installed. Unfortunately, the sound still persists.

It is most prominent when engine breaking. Again, it sounds like pebbles are knocking against the front fender and I can feel the "knocks" in the handlebar (but not footpegs).

Still sounds like the steering head bearings.... Can you check it yourself?

 

[KingY]

Yea head bearings or front wheel issue, have front wheel bearings been checked?

 

[rachtak]

Still sounds like the steering head bearings.... Can you check it yourself?

I'd like to look into that tonight, is there any way that a non-mechanically savy person with very limited tools (college dorm) like me could do in the parking lot?

 

[dpaul007]

I'd like to look into that tonight, is there any way that a non-mechanically savy person with very limited tools (college dorm) like me could do in the parking lot?

Don't need any tools for checking them. All you are doing is pushing/pulling/wiggling things and checking for movement. As far as actually replacing them, yes, you will need tools.

 

[TownsendsFJR1300]

I'd like to look into that tonight, is there any way that a non-mechanically savy person with very limited tools (college dorm) like me could do in the parking lot?

Like the mechanic did, put it on the centerstand. You can either put your car sizzor jack under the header to lift the front end, or have a helper, lean back on the bike getting the front wheel off the ground. I'd prefer to use the sizzor jack as its more stable.

ANY forward, up, down, etc, movement is NOT GOOD and not normal. The head bearings can be loose or worn. Basically what happens is you slow down and the forks tilt forward (clunking), once slowed, they settle back down (like a chopper) and clunk again into the rest position... The top triple crown (center nut could be loose-not likely). A regular maintainance check of all nuts and bolts should be done in either case, you may find a problem.

As noted above, you can check the front wheel bearings too (without tools) by just rotating it and feeling around by the axle for any knocking coming thru to the forks. Also, with the forks turned all the way to one direction, pull on the wheel further, checking for any slop. Its not as accurate as pulling the wheel but if you have obvious slop, you need to go further...

With the noise your describing, it shouldn't be that hard to find..

 

[TownsendsFJR1300]

Sorry, for not replying lately; been really busy. I can't replicate the sound while stationary.

Convinced that it was a problem with the chain/sprocket, I dished out $250 to get new ones installed. Unfortunately, the sound still persists.

It is most prominent when engine breaking. Again, it sounds like pebbles are knocking against the front fender and I can feel the "knocks" in the handlebar (but not footpegs).

Can I assume once the new chain and sprockets were on, the new chain has between 1.75" and 2" of up and down TOTAL travel, measured on the lower run, at one pin, just about at the lower, plastic chain guide? If its tighter than that, it will make a bunch of racket (new or not). Loosen it immediatly if its too tight (your tool kit should have the proper tools (short of a torque wrench) or have your mechanic re-adjust it..

The FZ6 has about the loosest chain settings of most chain driven bikes. Its NOT unusual for a mechanic to tighten the chain to half that, thinking it was good, ITS NOT..

 

[tosh23]

Its not your chain and sprockets, Check you head bearings, if you don't know how look at youtube... there is plenty of videos on the subject...
Also check your front discs and pads, if your pins are worn, if your pads are loose, ect ect..

 

[UHcougarJohn]

When my front wheel bearings went I was getting a front end knock. Could find anyrhing wrong untill I pulled the front wheel off.

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[ferritt]

I have had the self same problem / noise for a few days now, i have done all the things suggested but couldn't find anything wrong. Just had another look now after a short ride and noticed that the nearside front pads are moving slightly in the caliper and causing the noise. Try moving yours using a screwdriver or similar, i reckon yours will be the same.