The Rattling Riddle

[Rau]

How about this one.

Last month I rode to birmingham (from nottingham) and the bike ran fine as always! when I set off on my return journey, the bike really started struggling as if there was no fuel in the tank, when there was actually about 40 miles worth of juice in there. I filled the tank anyway but to no avail, still the same problem. So I pulled over to call a mate who is a little more wise on these matters. As I had recent had the plugs changed he suggested some crap might have gotten into the carbs so just to run it at relatively high revs for a while and see if it cleanered itself out. However, everythime it hit 6k revs, its would just cut out and drop back down to tick over speed (about 12-1300rpm) with the choke on, it would rev all the way to red line. I had no choice but to set off for home, as it was pretty late in the day by this stage (I should really invest in some breakdown cover!) so rode it at a combination of low revs and with a bit of choke and after about 20 miles it cleared up and was fine. However about 30 miles late, the bike developed a plasicy rattling sound at low revs in low gears (no noise up to 3k revs in first, then the rattling at 3-4k revs then fine again, and a similar case in 2nd and third).

I have taken the air box off the check if there was anything in there, and it had been put on properly after changing the plugs (my dad did the plugs whilst I was at work, and he can't be trusted do a proper job on anything other than his own machine), but that resolved nothing. I really dont think its the CAM chain, as it was replaced about 9 months ago, along with the tensioner, and the bikes done about 3k miles since then. Plus it doesn't sound metalic enough to be that.

The REAL puzzle is it only kicks in after the bikes done about a mile, its not there when it starts up, and if its left a few hours, it disappears again untill I have done another mile or so.

Any Ideas because I am baffled (and a little bit stupid also). I have checked the fairings ect, and it deffinately sounds like its originating from below the tank.

appreciate any input, or if anyone has heard of this before.

[Scott221]

If its happening a while into your ride that points to the engine becoming warm and then your problems start. Did you ride in rain? What plugs are you using?

[cargo]

I'd really need to be there and hear it for myself rather than guessing at something.

I assume the cam chain tensioner was correctly fitted ?

[RedexRobB]

Not the exhaust headers is it? Check the nuts are good n tight.

The fuel thing sounds like the fuel pump to me, dunno bout anyone else, may be whats making the noise too!

[Rau]

I do ride in the rain, but it was not raining when the condition developed. A for the plugs, they are CR9EK NGK Standard if I remember correctly.

The Tensioner was to the best of my knowledge fitted correctly. It was a good a freind of mine (Chairman of my bike club) who is a mechanic by trade.

Stupid question, but Exaust headers?

[masterofinsanity]

the downpipes mate, sometimes can work loose and can give a raspy rattly sound and you will lose performance if they are loose.

[Rau]

Good call. I'll check tonight as i'm off home now. Watch this space.

Cheers guys