Noisy engine ... with Video!

[stelladragon]

I know it's been raised a thousand time before, and I apologise for bringing it up yet again. I've taken two videos of my Dommie, one just after start up, and one 2 mins after when it's a little warmer. Noisy on the top end i think, but sweet when warm. The tappets have been checked very recently, and the rocker arms and cam are a little worn but uniformaly. It's got 48k on it. You thoughts as to the noise please????

Russ.

WHEN COLD -

WHEN WARM -

[dr155]

I'll name that tune in...


Horrendously difficult to determine , tbh , at first it sounded like a 'zorst leak from the joints....

However :
Book says to check the Crankcase Breather every 6,000k
Oil strainer in down tube every 6kk ,
Valve clearances should be checked when cold , intake 0.10mm , ex 0.12
with a special note :

" Special care should be taken when measuring valve clearance at the R/H exhaust valve .
The half-decompressor slightly lifts this , when the piston is before compression TDC . Therefore it is neccessary to position the crankshaft where there is no lift in order to obtain the correct clearance "

Any help ?

[AlanH]

Camchain noise on these motors sounds very similar to cam and follower noise and it's pretty difficult to tell the difference even using the screwdriver listening technique. Based on experience, I'd say if this noise was due to classic follower failure, it would be clacky when warmed up too. It could be a sticky camchain tensioner which frees off slightly and does its job when warm. After 48k, it's probably on the limit camchain wise.

The motor doesn't sound rumbly or knocky from the bottom end (at least not as far as I can tell from the vidoe) so I'd think that's quite a good example. Do the cam and followers and the camchain and tensioner and it should give plenty more service.

[IgorVigor]

Sounds a bit like the clutch on my CB500 :P rattles like crazy when cold...

Hope you cure the prob

[StumpyFingers]

It sounds like it could be the cam chain of the clutch basket.
At 48000 it could be either but a rebuild might be in order.

[yellowpurple]

For what it's worth, my limited experience would suggest top end definitely. I don't know what a roller bearing crank would sound like when the bearings are starting to fail, but I guess you would get the usual rumbling associated with shell bearings or knocking if the big ends were on their way out. If the oil consumption hasn't increased then this would be another indicator of top end wear. Maybe the cam chain is a bit loose when it's cold. At least it idles smoothly unlike mine......

[stelladragon]

Thanks for all the input folks. I think I'll do the camchain and tensioner and see how it goes. The clutch is nearly due anyway, so I'll do the whole lot together. Is it a very involved job?

Russ.

[AlanH]

It's not too bad a job. A couple of the cam cover bolts are favourites for snapping if the top hasn't been off in a while and that can be fun. Other than that, the only awkward bit is getting the clutch centre nut undone.

Good luck

[IgorVigor]

I havent ever done the clutch on my vigor, but I have on a few other bikes...

The trick to getting the centre nut undone is get the bike in top gear (might need rock the bike back and forth to go through the gears), and then preferably with someone sitting on the bike pushing the back brake on, the centre nut usually free very easily...

[datsun fan]

I usually drop a 2p coin inbetween the gear cogs or somewhere if you can get at them, generally stops things turning with no damage!