Engine Rattle

[KaiNinaste]

Greetings,

Firstly, apologies if this question has been asked over and over again but from the posts I have read none are very specific to my probelm (or that could be me...!).

Basically I have my Flynn, he's a L3 400 and he's gorgeous.

Anyway, I got him cheap becasue he has an engine rattle. It's not the cam chain or the clearances as they have all been sorted. It appers to get louder when warm and sounds more of a top end rattle. The engine has done a fair few miles but the engine is sweet as a nut, I just can't work out where this damn rattle is coming from!

He does have restrictor plates in as I am only 20. this appears to make him a pain to start (especially after he has been riding for a while beforehand) and also backfires occasionally.

A friend of mine suggested buying another top end head as it could be a lazy spring isn't keeping a valve very well behaved.

Please help, I love this bike but this rattle is driving me nuts!

Thank you.

Jade.

[R P Corse]

Could be shell bearings on the crank shaft, conrods may have play in them... Just a though

[cargo]

Two thoughts.......................why would a top end rattle make you think crank bearings ????????????????????????

And why would you replace the entire head for a "lazy spring"



Blind leading the blind I think


Top end rattle could be anything in the head.............. worn rocker, worn cam shaft bearing surfaces, broken valve spring in fact the rattle could just about be any moving part in the head.

A real favourite for top end rattles is an exhaust header blowing ? ?

[R P Corse]

Worn bearings making the conrods loose on the crank, rattling around... like I said, just a thought! Never said it was the correct approach, I haven't heard what their engine sounds like - I've heard what the cam chain sounds like and valve clearance sounds like if wrong/faulty that's why I thought it could be the shells on the conrods.

[hatatfatcat]

if a conrod was loose on the crank it would be a very noticeable knocking sound, really noisy. I know a nitwit (not me) who put the big end cap on back to front on one pot and it sounded horrible.

Best bet is check the valve gaps before you go and spend loads of money.

[cargo]

big ends dont rattle

when they are knackered they knock............................


like I said blind leading the blind