Help identifying rattle

[Bishamon]

There is a rattle on my Monster 796 which doesn't sound normal.  It seems to be coming from the left side of the bike, and it sounds (to me) like a loose bolt or screw, but I cannot find anything loose.  The noise is not constant/rhythmic and sounds more like a loose washer rattling against something metal.  It only makes the sound when in gear and accelerating; if I pull in the clutch and try to keep the engine revs constant, it will go away, and then return when I let out the clutch.  It isn't very loud, and it seems to be more noticeable when the engine is cold, and less when the engine is warm.   It also doesn't seem to be there when decelerating or when in neutral, but it there under even light acceleration.  It also seems to be affected by bumps in the road.   I think it has become more obvious over time, but I can't be certain.  I told the dealer about it and they could not find anything wrong.  I also had the dealer install a 14T sprocket, which seemed to have no effect (I figured the chain or sprocket might be causing the sound).  Does anyone have any ideas?  I'm worried that something will fly off and I'll end up stranded.  The dealer is ~2.5 hours away, so having them look at it again would be a P.I.T.A., unless I was taking the bike in for another reason.  Capturing the sound on video would be extremely difficult since I don't have a GoPro (or something similar) and I'd have to hold the camera while the bike is moving while also working the clutch and throttle.

[timeforpoptarts]

I noticed a slight rattle the other day when my engine was cold. For the life of me I wasn't able to figure out what it was. It was coming from the front left side, and seemed to only be present (or heard) in first gear while accelerating. I didn't hear it in higher gears or when the engine warmed up. I was sounded like it was coming from the sprocket area. Since it went away I was thinking it happened to be some dirt that I hit in a mud puddle.

[rule62]

check your chain tension

[skurvy]

I had a couple rattles that I couldn't pin down either. One turned out to be a washer and bolt on the exhaust heat shield and another rattle was one of the db killers! Double check that sprocket area too since it was the last thing changed on the bike. Maybe the front sprocket retaining clip?

[Bishamon]

I had a couple rattles that I couldn't pin down either. One turned out to be a washer and bolt on the exhaust heat shield and another rattle was one of the db killers! Double check that sprocket area too since it was the last thing changed on the bike. Maybe the front sprocket retaining clip?

I had thought the sprocket might be involved, but since I was having a new sprocket installed anyway, I was hopeful the rattle would be gone once the 14T was in place.  Unfortunately, the rattle did not change after the front sprocket was installed.  The chain tension seemed fine before (and the rattle was present), but I haven't measured since the sprocket was installed.  I assumed they would adjust the chain tension when they installed the sprocket, but I suppose I should check.

[thought]

Could it possibly just be the chain slapping against the bottom of the swingarm?  Even when correctly tensioned, the chain will slap... and you can hear it slapping at low speeds and over bumps.  Especially when you just start the bike and it's not smooth yet and lugging a bit.

Do you hear this rattle at 4k+ rpm and on smooth roads?  Or only at low speeds and under 15 mph/4k rpm... where the engine is balky?

[skurvy]

I had thought the sprocket might be involved, but since I was having a new sprocket installed anyway, I was hopeful the rattle would be gone once the 14T was in place.  Unfortunately, the rattle did not change after the front sprocket was installed.  The chain tension seemed fine before (and the rattle was present), but I haven't measured since the sprocket was installed.  I assumed they would adjust the chain tension when they installed the sprocket, but I suppose I should check.

oops sorry, misread your original post about the rattle being there before/after the 14T switch. I remember I also had a rattle from the license plate too. Even though it was securely bolted on, the plate would still vibrate against the mounting plate. i just used a piece of double sided foam to stop it vibrating.

[Bishamon]

Could it possibly just be the chain slapping against the bottom of the swingarm?  Even when correctly tensioned, the chain will slap... and you can hear it slapping at low speeds and over bumps.  Especially when you just start the bike and it's not smooth yet and lugging a bit.

Do you hear this rattle at 4k+ rpm and on smooth roads?  Or only at low speeds and under 15 mph/4k rpm... where the engine is balky?

It seems to be there all the way through the rev range, and it's more evident under acceleration; if I release the throttle, it goes away, and comes back as soon as I open it back up.  It also goes away if I pull in the clutch while maintaining revs, which probably eliminates anything in the top part of the engine.  It's barely there in first gear, oddly enough, but definitely there in second, third, and fourth (possibly fifth, but once I get up to those speeds, the wind noise starts to drown it out).  I will measure the chain tension, but it definitely sounds like something is loose and ready to fly off.   

[Bishamon]

The problem was diagnosed and resolved by a Ducati master technician as a noisy/faulty check valve in the emissions cannister.  He said he had never experienced this specific issue in his 30 years working on Ducatis.  He replaced the cannister and the noise is gone.  Don't ask me how the valve can account for all of the specific symptoms I experienced (in particular: how the noise would go away if I pulled in the clutch while maintaining revs), but the proof is in the result.  I am happy. 

[Curmudgeon]

Since you're not in California, curious that he did not volunteer to remove the canister entirely and plug the holes with the correct sized bolts. In general, losing that thing eliminates a few choice "quirks".  You can also replace the left side radiator shroud for ~ $30 so that it looks just like the right side.

[Bishamon]

Since you're not in California, curious that he did not volunteer to remove the canister entirely and plug the holes with the correct sized bolts. In general, losing that thing eliminates a few choice "quirks".  You can also replace the left side radiator shroud for ~ $30 so that it looks just like the right side.

I was a little surprised as well.  The same tech offered to remove the canister on my Sport 1000 free of charge when I has the belts changed in 2010 (I accepted).  Mind you, the canister isn't as noticeable on the Monster.

[Bishamon]

UPDATE: The noise returned, so I had the canister removed, and the noise remained.  It turned out that it was the chain!?! Despite being clean and (apparently) well lubricated, a good lube job later and the noise is gone.  What the heck?  How often do these things need to be lubricated?  I used Maxima Chain Wax this time instead of the DuPont stuff I have used before, but I'm still quite surprised.  I'll keep my eye on the mileage before the sound returns, as I'm sure it will.

[Privateer]

  How often do these things need to be lubricated? 

I do mine about every 400 miles, some people will say every 2 fill ups.  I just do it every other friday (when my bike isn't broken /grr ).

[kokis]

It also might be GRM, and\or gearbox.

[Bishamon]

I do mine about every 400 miles, some people will say every 2 fill ups.  I just do it every other friday (when my bike isn't broken /grr ).

I've been doing it every 500 - 1000 kms (~312 - 625 miles), but from the noise you would think I had ridden 10,000 miles through a sand storm.