Being new to big Singles, I am wondering whether it is normal to have some black smoke coming out of the exhaust while the bike is warming up. Once the bike is warm there is no smoke and it smells and runs sweet.

Is there a mixture problem, valve or piston-ring issue or is it all perfectly normal? The bike is a 2000 4PT with about 18,000 African miles on the clock.

Cheers (in ignorance) George

Black smoke indicates unburnt fuel. Choke out for too long/too much? Air filter clogged? Someone fumbled with the mixture?

------------------
Fred, XTZ660, Holland.

Black smoke indicates that the engine is getting too much fuel.

It could be something simple like a clogged air filter or choke cable adjustment or part of the choke mechanism on the carb fowling on something or just needing a clean and some lubrication, WD40 etc. Alternatively it could be something internally in the carb necessitating a strip down.

I had an XL once where the choke body had seized, probably due to it being stored for two years without being run, which just needed cleaning and a good soak in WD40.

It'd be worth checking valve clearances too.

[This message has been edited by mcdarbyfeast (edited 18 November 2003).]

Valve clearance on a Yammie??
I've never ever had to adjust it.

------------------
Fred, XTZ660, Holland.

Just a thought Fred!

Cheers Guys,

I've got a new air filter in there. I'm thinking it might be me having been a bit clumsy with the pilot screw. Would this cause the smoke? Is the setting about 2 1/2 turns out on a 4PT?

Can somebody please tell how to set my carbs correctly. I have a 1VJ and use it mainly for town riding at about 1000 metres above sea level.