Problem: Knocking/Popping

Okay, I'm sorry if this question has been asked a thousand times already, but I'm pretty new to motorcycles and mechanical repair in general so I have to ask this in case my bike is about to explode when I'm doing 70 on the freeway.

I've had my '07 FZ6 SHG for about two years now. Within the last year, the bike has started making an unexpected noise. It is somewhere between a knock and a pop and sounds to be coming from low on the left side. I can feel the sound through my left foot rest. It is starts when I hit the gas and gains in volume and frequency when I go uphill and also gains frequency with increasing velocity (not RPMs). Between 20 and 30 miles per hour, the frequency picks up, the volume reduces, and by the time I'm at about 35 mph, the sound and the feeling through the foot rest seem to be gone.

I've heard a few explanations on why this might be occurring. There's the mysterious Yamaha Knock that all Yamahas seem to get. When I took the bike into a mechanic, he said it was probably gas in the oil, but the tech who changed the oil didn't mention any gas smell (I tried taking a whiff of the dip stick, but wasn't sure if that was gas or oil I was smelling). I've heard mention that knocking or popping can be a function of the valves and that servicing them will fix the problem. I've also read that the chain could be the issue (I run that chain pretty dry, so I'm leaning in that direction) or possibly the arm that holds the chain in place (blanking on the name right now).

Are there any possibilities I've missed? Do the symptoms jump out as having a particular cause? Is there something else I should be looking for? Thanks for any help that can be provided!

- Chad "Exploding Transmission" Uskoski

:welcome:to the forum Chad.

What comes to my mind first per your description is a possible worn front sprocket, chain or both. Also cleanliness is next to quietness so you might pull the cover and clean the sprocket area up because it gathers a lot of grunge in that area.

Also chain slack and rear wheel alignment are important. If they are not correct you will experience noise and/or chain, sprocket or output shaft bearing and seal failure.


You're not deadheading your engine by shifting into higher gears too soon are you? That would cause pre-detonation knock. Bad fuel can also cause this but I doubt you've put in an octane level below the minimum for that engine's specs.

Having the same exact issue at the moment and you couldn't have explained it better. Purchased my 07' about 6 months ago with 4400 on it (now 5k on it.) Didn't really notice as much of the knocking when first purchased, but seems like it's becoming more evident as time goes.

Also haven't got a definite answer on this. Must just be this Washington air.

phil_dennis90 said:

Having the same exact issue at the moment and you couldn't have explained it better. Purchased my 07' about 6 months ago with 4400 on it (now 5k on it.) Didn't really notice as much of the knocking when first purchased, but seems like it's becoming more evident as time goes.

Also haven't got a definite answer on this. Must just be this Washington air.

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The OP described the knock or pop could be felt through the left foot peg. My first thought is the front sprocket/chain....

Sent from Moto's Motorola

As mentioned above; i'd clean, clean clean the chain. Ride to 10min and then lube the daylights out of it.

Grab a grunge brush and expect to make a soupy mess. That chain is expected to deliver all of the engines power. It needs to have lots of lube and move freely.

Once cleaned and lubricated every link should roll off the front sprocket in the same manor. NONE - should bind up or kink/arch or look any different than the others.

At every other cleaning I roll every roller on the chain to confirm each is happy.
FWIW: With these dry lubes, I find most only last 400 miles. With a clean chain that gets me 400 miles, then I lube every 200 until it looks dirty (~800 miles) and clean it. Repeat!

Grab - grunge brush, solvent, lots of old rags, news paper and clean it spotless. Ride it, wipe it down and lube it several times. Test each roller and look for kinks off the sprockets!

Motogiro said:

:welcome:to the forum Chad.

What comes to my mind first per your description is a possible worn front sprocket, chain or both. Also cleanliness is next to quietness so you might pull the cover and clean the sprocket area up because it gathers a lot of grunge in that area.

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This is where I'm leaning. The chain I'm sure desperately needs to be cleaned and lubed, and the if the sprocket area's picked up the grunge too, then it'll need a cleaning as well.

Motogiro said:

You're not deadheading your engine but shifting into higher gears too soon are you? That would cause pre-detonation knock. Bad fue can also cause this but I doubt you've put in an octane level below the minimum for that engine's specs.

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My shifting might be a little early in the low gears, but its pretty close to what the manual says. 17-19 mph to go to second, close to 30 to go to third.

The gas is possible. I use the lowest octane the stations sell, but tend towards Chevron gas, which has given me the fewest problems in past with cars. I'll try upping the gas octane next tank.

Thank you!

Just a followup, but cleaning the chain really did the trick. I didn't have the tools I needed, so I wound up using a travel toothbrush and paper towels, so the problem isn't completely taken care of. But, the knocking is almost completely gone. When I get the right tools and a good spot to work on it, I'm going to pull the chain and sprockets completely off and do a better job of it, or possibly just replace them entirely.

Thanks to everyone here! Glad to know its not my transmission going out...

As Finaimpact and others posted, a Grunge brush works very well at cleaning the chain. You can use Kerosene or chain specific cleaner as well. A paint brush in the front sprocket area works well too.

Besides a good lube, correct chain adjustment is critical. Please check your owners manual on the procedure, but 2" TOTAL up and down play while on the centerstand is the sweet spot (at the tightest point in the chain as you rotate it).

BTW, as the chain wears, it will get noisier, links kink, etc. Its pretty slow to develope but will over time, especially if not maintained (lubed). If it has kinks, and won't straighten out, its time to start looking at new chains (and sprockets). I wouldn't cheap out here, get the best x ring chain you can afford.

The stock Yamaha masterlinkless chain is a very good chain but you have to loosen the swingarm to sneak it in. Contrary to the shop manual, you don't have to pull the exhaust, or the entire swingarm.

BTW, as noted in your first post, "running the chain pretty dry" is the best way to wear out the chain/sprockets, hurt gas mileage and cause your issues.

If bad enough, you can throw your chain thru the engine (replacement engine time!). You don't need a shop to lube your chain, its very simple and needs to be done. More often if ridden in the rain.

Here's a link for free owners manuals if you don't have one: Boneman's FZ6 Site - Mods

All the basic maintaince procedures are in there including oil changes, chain maintainace, etc.

cuskoski said:

Just a followup, but cleaning the chain really did the trick. I didn't have the tools I needed, so I wound up using a travel toothbrush and paper towels, so the problem isn't completely taken care of. But, the knocking is almost completely gone. When I get the right tools and a good spot to work on it, I'm going to pull the chain and sprockets completely off and do a better job of it, or possibly just replace them entirely.

Thanks to everyone here! Glad to know its not my transmission going out...

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Good to hear! or should I say not hear? :rockon:

:Flash: Another important thought is safety when working around the chain and sprocket. Chains and sprockets can cause severe damage to any body part that can be grabbed. Be alert and never clean chains or sprockets with the engine engaged. Keep any rags away from sprockets when wiping the chain. Doesn't hurt to wear protective eye wear when you're spraying and brushing.

Thanks for the info everyone. '05 with 28,000. Had the recommended full service at 26,000 but now here clicking at low rpms if the engine is loaded. My first thought was the chain, noise is not rhythmic, more random single, or grouped clicks/knocks from left side, Doesn't do it idling or in gear on the center stand, yes I was very careful and didn't apply much gas. Otherwise runs great. Would post a video but have to pick a new phone tomorrow. Must admit I don't take care of the chain like others. Always serviced and ran synthetic though.

buzzard breath said:

Thanks for the info everyone. '05 with 28,000. Had the recommended full service at 26,000 but now here clicking at low rpms if the engine is loaded. My first thought was the chain, noise is not rhythmic, more random single, or grouped clicks/knocks from left side, Doesn't do it idling or in gear on the center stand, yes I was very careful and didn't apply much gas. Otherwise runs great. Would post a video but have to pick a new phone tomorrow. Must admit I don't take care of the chain like others. Always serviced and ran synthetic though.

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If that's the original chain (not even counting LACK of proper maintainance), its due for replacement, along with sprockets.

You can probably see some links NOT straightening out as they come off the front sprocket.

A thrown chain thru the engine case is NOT cheap..

For the record, knocking problem solved. I cleaned and tightened the chain. Will plan on putting a new chain/sprockets on this winter. From the best I could measure, the chain slack was right at the upper limit, but that was enough to cause problems.

Sounds like some stiff links on the chain

You can loosen them by taking the chain off the rear sprocket and then bending them them back and forth by hand with a little oil. Not sure if the seals are already perished by this point though.

Usually it means your chain is on the way out though, especially if they stay tight. Better to prevent them becoming like this in the first place with regular oiling.