Bike developed this problem the other day, almost sounds as if the kickstarts engauged but a lot louder. Think it's coming from the bottom end somewhere. Thought it was the clutch at first but that was a different problem lol. Took a video, the rattling sounds a lot deeper than in the video though.
piston slap or bottom end knock there,when its running put your hand over the end of the silencer and rev it then let it run till it dies with ur hand over the silencer
this stops most of the exhaust noise so you can hear the mechanical noises from the engine
may give you a better idea of where the noise is cumming from
iv got one of these there ace for pinpointing noise
WHIRING. IS NORMAlly worn bearings the clutch bearing is normally a common fault on small engines
Well my noise isn't so much a whirling more like a little whistle. I'm sure it's not the bearings since it only did it when I first got it or when I did the rebuild. Not now that it's been thrashed!
Found what it is, was the piston knocking on the power valve. Unplugged the pv and started it, noise went. Only thing is I'm not sure if it's damaged the piston/cylinder. Will be pissed off if has, I asked the guy at shop I got the rebore done if that was possible on +1 os and he said it definitely wouldn't. And he supplied **** gaskets, he'll be getting an angry phone call soon I think...
Think it's got worse, got the dremel out, took a bit off the powervalve, was very close before. Went to start it and it's making the same noise, but it was definitely hitting valve before. So I'm guessing there was bits of shrapnel flying about and that's gone and now damaged the piston and probably cylinder. And calum, I did everything myself except the rebore obviously, just pissed off that I followed his advice and left the pv alone. Am quite suprised it lasted so long though tbh, must have done a good 5-600 miles by now.
outch, top end strip the n pal get in and ava look
5-6000 miles wunta fort it be good
soon as things start contacting it contamanates the cylinder /engine with microscopic alloy partickles and over time its just like grinding paste, it will travel alway round the engine/crank/bearings/bore and cause exsessiv wear, probly y u only got 6000 miles out of a fresh build
Yeah gonna be a job for tomorrow was hoping I'd get away with not having to strip it no chance though lol. Wondering if I can get away with using the same piston if I clean up the edges of the crown, not sure though. Also where does everyone get head gaskets from, I ordered one from AJ sutton, took 2 weeks to get here, cost £20 and blew my bike up lol. Didn't realise the head gasket had to rebored as well lol that's what all the fine shavings are from I think, not the power vavle, although it was making contact as well.
got a piston just a bit worse than that in me field bike fella (same damage as yours plus a score down the front from a bit of barrell breaking off) took a file and sandpaper to it and it now runs fine.... do you really want to risk it though? if mine breaks,i chuck it in the van and go home.... 45 quid for a new piston kit buys a lot of piece of mind on the road
