Hi, I have a mk2, she runs great no engine noise until I'm accelerating and I got this annoying bloody rattle at around 4-5000 rpm (I'm guessing here as have no rev counter). Any one experienced similar problem. ?

my mk2 used to do that, it was (i think) the powervalve 'chattering' as it started to open,
i say think as it sounded like it was coming from up high on the front of the engine and it certainly wasnt the piston/barrel etc as i had it apart to check and all was well,
i just ignored it and it didnt get any worse or cause any problems

could be chain/ sprockets? you have chain guides and sliders?

I've had 4 different barrels on my Mk1 and they all sound different, particularly with rattles at specific rpm. All had just had rebores and new pistons.

Like 69Chris I think it's down to fluttering of the powervalve and nothing to be worried about.

thanks everyone..I disconnected powervalve cables and 'jammed powervalve' so it could not move..then took bike out....exactly same rattle still there...so I feel confident it's not that..cheers for all advise

May I suggest that your 'jamming' the powervalve still allowed the movement of the valve on its shaft and the movement of the shaft inside the barrel. This is what I mean by 'fluttering', not the movement induced by the cables.

OK, understood...thinking cap back on ! thanks

pac wrote:OK, understood...thinking cap back on ! thanks

And here's the fix,
http://www.amazon.co.uk/Pairs-Howard-Le ... 090&sr=8-1

Seriously, tracing noise/rattles is legendarily difficult.
Check all bolts are tight, can you make some washers out of shim for the lever pivot points.
Mike

A bit off topic - Have you found how many 'new' rattles appear when you take your helmet off while the engine is still running .

Not taken my helmet of yet ! OK Mike, the link (to the ear plugs) was really appreciated..even made my Mrs Chuckle and she has as much interest in m'bikes as I have in girl guiding ! cheers from Paul

pac whats wrong with girl guiding i had a very big interest in them when i was about 14 years old

^^^^^ you keep your ging ganging and goolying to your self, thanks .
Mike