Mystery noise NOW WITH VIDEO!

Kitch · Post by **Kitch** » Fri Aug 24, 2007 4:50 am

Presented for your delictation today is a mystery...

One full of cunning, intrigue and twists...

I have a mystery noise. I'm hoping somebody can tell me what it might be so I can look at making it go away.

So, the symptoms:

The noise sounds like a "slappy" noise, almost like an exhaust that's blowing from the headers. The noise matches the exhaust pulses and changes them from "put put put" to "twhap thwap thwap" (how's that for technical

)

It only occurs at idle speed and is intermittent. Sometimes it doesn't do it, sometimes it does. It also makes little difference whether its just started or been running a while.

What we know:

The bike has all fluids, oil, petrol, coolant etc.

The clutch feels fine at the lever.

There is no noticeable loss of power anywhere.

The CCT's are 3000 miles old with uprated springs and were fitted professionally.

It is due a service (20k)

There is nothing I can see that is hanging off or leaking anywhere.

So, thoughts? Ideas?

Thanks

*edit* new and improved, now with motion pictures. I think it's most likely cam chain or CCT. Note how the noise is loudest on the left side near where the CCT is and also how it disappears with the tiniest amount of throttle.

chaz · Post by **chaz** » Fri Aug 24, 2007 9:29 am

hope not, but does the slap sound like its from the cylinders area?
maybe piston slap, small ends worn!!
can you pinpoint where its from.
could just be a blown gasket on the exhaust or a small hole appeared.

Pete.L · Post by **Pete.L** » Fri Aug 24, 2007 9:46 am

1)Any popping on the over run?
If there is it could be an exhaust problem. What about the connection to the header by the rear shock or the copper header gasket on the exhaust port?

2)Put a screwdriver or metal rod on each of the cct's in turn and put the other end to your ear. Just because they've recently been done doesn't mean you can rule them out.

Good luck
Pete.l

Kitch · Post by **Kitch** » Fri Aug 24, 2007 11:40 am

boinged for "now with video" for the "new posts" readers

iggy1966 · Post by **iggy1966** » Fri Aug 24, 2007 12:50 pm

Sounds like you have a bad case of clutch rattle, does it get any better when you pull the clutch lever in???

Doesn't sound like CCT's to me, if it where CCT's the noise would not go when you increase the throttle.

Anyone Else have any thoughts??

Post by **kevg** » Fri Aug 24, 2007 1:00 pm

sounds like its worse on the left side away from the clutch...

Pete.L · Post by **Pete.L** » Fri Aug 24, 2007 1:17 pm

Front tensioner.
If I remember rightly (Chris might be able to back me up on this) as the revs rise normally the tensioner screw backs off by about 1/4-1/2 a turn. I reckon the tensioner has backed off and stuck so it sounds fine when the revs are up but as they fall it doesn't retension and tighten back up.
Thats my best guess.

Pete.l
P.S my APE tensioners sounded like that before I adjusted them properly. When cold at low revs I could hear a little slapping and then as the revs came up it dissapeared.

Kitch · Post by **Kitch** » Fri Aug 24, 2007 1:17 pm

iggy1966 wrote:does it get any better when you pull the clutch lever in???

nope, same.

kevg wrote:sounds like its worse on the left side away from the clutch

thought the clutch was on that side...

sparrowlegs · Post by **sparrowlegs** » Fri Aug 24, 2007 1:40 pm

Found this on youtube...its of an SV650 with a rattling cam chain...yours sounds different

also on a VFR800

Kitch · Post by **Kitch** » Fri Aug 24, 2007 2:07 pm

Thanks Caz, good find and you're right, mine sounds bugger all like that.

So, if its not CCT's I have no clue.

Gonna get a pro mechanic type geezer to have a look. Was just hoping to narrow down what the possibilities might be before I take it in.

Post by **kevg** » Fri Aug 24, 2007 4:27 pm

think the mechanism is on the left from the clutch lever, the basket is under the cover on the right hand side.

derryUK · Post by **derryUK** » Sat Aug 25, 2007 5:37 pm

I agree with your description after hearing it on the vid.

It sounds like something is slapping in sympathy, almost like something loose on the bike, but if that were the case I can't understand why it then goes away on opening the throttle.

It almost seems like it is connected to the throttle somehow, have you had a poke around under the airbox?

Just guessing.

Derry.

Post by **sirch345** » Sat Aug 25, 2007 8:36 pm

I would have thought the same as Pete that more than likely a CCT problem

But after listening to your video I'm not so sure, but after saying that, recordings can sound different to the original sound

My first port of call would be the CCT's

Chris.

clayderman · Post by **clayderman** » Sat Aug 25, 2007 10:22 pm

Are you sure its not just because the tick over is set too low. What's it idling at?

Kitch · Post by **Kitch** » Sun Aug 26, 2007 12:52 am

a good point Clayderman, but my tickover is at 1400.