My WM20 has the standard carby fitted and once you get it started. It performs well. I am having a hell of a time starting it and even more so when it is hot. I have set the tappets (side valve) set the timming, points are cleaned and gapped, new pick up on the mag, new plug, seems to have good spark however I can not get enough fuel into it to get it started. I can kick it over and over but the plug always remains dry and it wont fire, I've stripped and cleaned the carb, the needle is on the second notch I can tickle it to flood but it doesn't seem to get into the cylinder. Any thoughts. By the way do you have to have both fuel taps on?
Cheers
Roger

It sound obvious, but is the fuel filling up the float and entering the carb? I had the same problem, and it turned out the gorse on the fuel taps had a sediment build up , prohibiting the flow of fuel, also when hot, especially ( like me ) if you have copper fuel lines, the heat can evaporate the fuel quicker than you can get it into the engine, yet when running, even when at high temperatures, the engine draws it in quicker than it can evaporate.

Regards

Ross

email (option): T58white@hotmail.com

Could have a point there, I have metal lines but thinking about it, I tickle the carby and it over spills but after a while of kicking and I try tickling again it takes ages to get the fuel to spill out. I will check the flow rate in the morning

Do you have an insulating washer between the carb and barrel?...This should be Tufnol or similar and at least 1/4" (6mm) thick...

Also, have you checked the spark both hot and cold?...Ian

email (option): ian@wright52.plus.com

A faulty mag with give the same symptoms, especially not starting when hot. It could be your capacitor breaking down.

email (option): horror@blueyonder.co.uk

If you are ABSOLUTELY, TOTALLY, convinced it is the carb.

Its an ignition fault ...............


However ....
Make absolutely sure you are getting fuel-flow to the carb -
I slacken the nut holding float-chamber onto carb-body, turn the fuel on and catch at least a margarine-container full (goes between carb and mag on a Norton) of petrol - it should fill rapidly and test the entire fuel flow path.

Before pouring petrol back in tank - have look in the petrol to see if any water in it (a problem for me, trailering bike around in the rain)

A 'quick' magneto 'bodge' is a Sparkrite capacitor that fits under the points - no need to remove mag/armature to do recommended 'snip' job - if the capacitor's the problem it will improve things and more importantly point you in right direction.

email (option): ginantonik@tiscali.co.uk

I went to the shed tonight two kicks with decomp lever in, retard about 1/4 advanced throttle open, picked up comp stroke and away she went. Left it idling for five minutes turned it off, tried starting about six kicks thought I would try wide open throttle second kick away she went. Repeated idle warm up and it started again. Need to go for a ride and get hot so I can try then. Only thing I have done is retension the head and replaced the plug lead although the old one looked good I noticed last night once it got hot it felt very limp. So I will have to wait until tomorrow night to try again. Any thoughts as to why the wide open throttle works but I don't need it when cold
Cheers
Roger

The wide open throttle allows both more air and more fuel in, when the engine is hot, the requirement for more cold air and is greater, so the extra 'fresh' oxygen and fuel, make even the smallest spark count.

Regards

Ross

email (option): T58white@hotmail.com