Things that go bump in the night - he-ye-lp!

[Lord Stig]

Noises. Yes I know it's a common subject on the forum, but my AT seems to have developed a new noise, and it's one I've not come across in 11 years of having TAs and ATs. I noticed it last week sitting at traffic lights, and was wondering if any of you cognoscenti out there had come across it before.

Noises are difficult to describe in words, aren't they? Here goes. It seems to be coming only from the front cylinder and appears to be from the top end (not so easy to tell though), and is on the nearside (so nothing to do with the clutch). The sound is medium pitched and more of a knock - not a tap or rattle. Sitting on the bike it sounds a little like a Volvo 340 starter motor, or maybe a Renault one; a sort of chortle.

I've not heard anything like it. It doesn't sound anything like clattery valves, the metallic ting of piston slap, and it certainly isn't the deep knock of main bearings (not that it comes from that region any way). I had an engine that dropped a valve locknut once - that sounded like a diesel (this possibility did occur to me because I adjusted the valves a few weeks ago; although not much needed adjusting I get paranoid about loosening things that have stayed secure...until I got my hands on them).

It occurred to me that it could be either play where the cam runs in the head (a Honda bugbear) or perhaps the cam chain. Since I've never heard either when they are a problem, I wondered if anyone can describe what they sound like. This sound isn't always there, so the intermittent nature could be a clue, and the fact that it's centred on the nearside does suggest to me it's the cam chain.

I've also notice a greater thirst for oil - I changed the oil the weekend before last (just oil without filter - no metal particles were apparent, but I didn't look so hard), and since then it's used 1/2 ltr in almost 1000 miles. There is a momentary cut out occurring when cruising at part throttle, but I'm pretty sure that has nothing to do with it the noise though.

Any thoughts well appreciated. Unless it turns out to be something loose knocking against the front cylinder (unlikely) it will probably be expensive and time consuming to fix. Since the thing has cost me a fortune over the last few weeks I could do without another problem......

Cheers - Stig

[YEN_POWELL]

Stiggy old boy,

If you're front coil is playing up then you can get the odd fluffy bit when one cylinder misfires at those sort of revs, it's happened to me. I just clean up the two low tension spade terminals on the front coil which catch all the rain/roadcrap with a little file. Could also be the noise (front cylinder misning very very ovccasionally)although mine makes a different worrying noise from everywhere at some time or another and has done from new.

I top up my oil every 100 miles or so, just a little off the high mark on the dipstick after motorway travel (which is mostly what I do these days). Again it's done this since new too.

[Lord Stig]

Ah, Yen! Your advice is always very well appreciated! I'll have a look at that coil as soon as I can - I figured it might be something like that because when I first became aware of it, it used to be in the wet. Knowing what the other electrical connectors are like, it's quite likely this is the problem. With the chain on its way out and making noises like it's about to snap (as the last one did before it snapped) I've been taking it really steady - great for economy, but probably makes any misfire more obvious.

It could also be the cause of the noise as you say. It makes sense if the spark isn't too good and the combustion is uneven. One thing I do need to check is the tightness of the plugs - now I think about it I remember another bike that made a similar noise, which turned out to be a loose plug. In this case it would be the front plug behind the rad, although I can't see they's be loose.

I'll keep an ear on it - if your extensive experience is anything to go by it might just go away..... Thanks for the advice.

Stig

[YEN_POWELL]

I've had the loose plug noise, even thought it was the camchain. It's the deep ones that I'm frightened of overtightening. They don't have to unscrew much to make an almost untraceable noise that seems to come from anywhere but the plug area.

Those front male spades get the whitey bluey gunk on them. A good scrape witha scalpel and file sorted mine, you don't have to remove the coil which is good cos it's almost impossible to do access wise.

[africatijn]

It is not the pedestrian-traffic-light-clicker?

Had me worried for a while.... Thought major things were wrong, then I switched off the engine, and the noise stayed...

Man I felt like a fool

I know this does not help you, sorry.

Tijn

[Lord Stig]

It is not the pedestrian-traffic-light-clicker?

Now you've got me. What is one of those? I'll probably kick myself when you tell.

Well I ruled loose spark plugs out last night, but the LT leads on the front call will have to wait until the weekend.

Stig

[africatijn]

Here most pedestrian traffic lights have a relay clicking in the light post, for the blind

Quite confusing... You can solve this problem by listening to your bike while not standing next to 'em....

Told you this wasn't of any help


Tijn

[Lord Stig]

Aaahhhh! All is clear! I can see why that would be confusing - it's like when you sit behind a diesel van and think "grief, my AT engine's about to explode!". The clicking device sounds like a good idea; we don't have quite the same thing here - they sort of whistle at you.

Stig

[YEN_POWELL]

I put in traffic lights and ped crossings for a living. Have you seen the rotating cones on some Pelican crossings, most people don't know they are there. Under the push button box upside down, is a conical brass knurled knob. WWhen the green man lights up and the beeper starts, this thing spins round. It's for deaf and blind people. Impress your friends with this piece of useless trivia or better still make them touch it without saying why and frighten them when it goes off.

[jvaughan]

I usually avoid putting my hands under such things for fear of picking up chewing gum or worse