Jetting would be different for a carb with or without an air filter. A carb jetted for an open mouth will be chucking far too much fuel in if you then put an air filter on it.

It also has the black and silver paint job Roger which I think was only the 1920 season.

Thought I'd show you my 1920 (or maybe 1919) Ariel roadster now its mostly complete. Going to get it registered now, then its full speed ahead for the final push.

Which one is you Karol?

Yeah - a bit too close to the exhaust tappet. Must have been just hitting it at speed. Readjusted so that it lifts the exhaust valve just before the control level hits the handlebars and all is golden.

So, I have concluded the investigate by returning to the scene of the crime - I readjusted the valve lifter - hesitation gone. Just need to put the carburation back to where it was. Thanks to all that tried to help.

Petrol won't leak out unless the engine is stopped. The inlet runs under vacuum so will suck air in. Not a good idea.

General consensus on the AOMCC FB page is to start at £2k - so if there is any interest out there that's the starting point for negotiations. Drop me a PM if you are interested.

I have Dave. Its on the list to try.

Mine is a top feed float chamber Nev. And its probably cleaner than when it left the factory having had it apart several times trying to find a cause. Now I'm pondering - this problem appeared after I overhauled the top end - valves and guides and a small end bush. I've checked valve clearances, and...