white ash build up on exhaust valve stems

I've been poking about (the motorbike) with a cheapo endoscope I got recently and found white ash on the exhaust valve stems, from reading about it, it's either normal or the engine running is running lean, possibly from an air leak. 

Theres no white deposits on the spark plugs and the engine was running fine before I started pulling it apart, aside from a loudish tapping noise after doing the valve clearances, however I've subsequently quadruple checked these and they're all in spec.

Bike is running a Fuel end can and I think I put in a K&N air filter. I'm going to replace the carb rubbers when I reassemble. 

Anyway here's a link to a cpl of pics + vids of the stems and the engine running.

What do ya recon, keep calm and carry on?

If it is a poor mixture, the spark plug is the best reference.
Others: valve seals / uk fuel type ....
If there was an undue intake of air it would accelerate by itself and idling would be chaos ...

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Ok great cheers guys, all seems ok for now then. I didn't think they looked bad but as I've never looked at them before, I thought best to check. Also removed the exhaust studs without snapping anything this afternoon. Things are looking up...

Thoughts to the engine noise? It's way more 'tickity' than before adjusting valve clearances and it got pretty loud at higher revs, but maybe its just something to get used to. I'm kind hoping it just goes away when I put everything back together. When it last went for an MOT the mechanic noticed the noise and checked the exhaust for a leak, which there wasn't. He wasn't overly concerned about it however.

It's pretty normal these days due to the petrol being diluted with ethanol which causes a weaker mixture. On the positive side of this, it tells that you're not burning oil 

Good stuff, may well give everything a clean and lap the valves anyway while I've got the head off. Think the extra noise might be from the spark plug hole as it blew out the plug on right cylinder not long after I took the video.

geewhizz wrote:Good stuff, may well give everything a clean and lap the valves anyway while I've got the head off. Think the extra noise might be from the spark plug hole as it blew out the plug on right cylinder not long after I took the video.

I think that it's certain to be a likely suspect