Hmmm!
She starts but won't sustain. Twisting the throttle has no effect on the revs.
Stripped the carb and float bowl and checked the needle etc.
Bit of a poser this one - anyone seen this?
Andy
Does the throttle slide lift when you twist the throttle? You can tell just by poking your finger into the carb as you twist
Is the fuel flowing through the tap fast enough..I've had a blockage above the tap before now..John
She fires and runs very hesitantly for about 10 seconds - no response from the throttle - as though it is not connected.
Plenty of fuel around and the throttle slide, needle and air valves work as advertised.
Hmm??!
Does opening the throttle kill the engine ? Has this just happened or has it been like this since it went back together ?
yes it does Tom,
No - I have had it round the block a couple of times.
1 step forward, several back
Are you sure that the needle is attached? If the little clip comes off, it just sits there blocking the jet, it'll run on the pilot jet but opening the throttle lets more air but no more fuel in .its hard to feel it move as the throttle has to be wide open before you can possibly get a little finger in ( depending on finger size !)
Dave Thomas
Yep - checked the needle - even shifted it up to notch 3 after a bit of advice from Vic
Makes me wonder if the pilot drilling in the jet block is restricted,assuming it's a 276 or type 29.
I had problems with one and had to drop the jet block out ( you must warm the body with hot water to do this).
On the engine side of the block is a recess with a drilling going down to the base of the block, at the back of this recess is the drilling for the pilot feed. They can very easily block with what appears to be varnish , a by product of using modern fuel..John
I'll second that about the pilot circuit.. My Velocette ( recent purchase in May )wouldn't start recently, I kicked it til I was sweating, then got pushed around a pub car park, and when it fired, it would die on opening the throttle. Turned out the pilot circuit was gummed up. My bike hadn't been used much for a while until I took ownership, and it seemed I'd disturbed a lot of sludge
Just a thought - you haven't by any chance swapped the throttle and air lever cables over?
Thanks for the advice Gents,
All fingers point towards the carb so, when I get back from work, I'll give it a full strip down and clean up.
Stay posted for the next thrilling episode!!!
Cheers all
Andy
Found it!
The carb and fuel supply were all fine.
On inspection of the rocker box, we found the inlet valve rocker arm had a sheared key. No inlet air!
Off to make a new key and thanks to Chris Roberts for being a genius!
Well that's great that you have found a fault, there's nothing worse than a fault that cannot be traced.
Well spotted.
The exposed valve gear does make finding these things a bit easier as you can see it's not bobbing up and down as it should.