Trouble starting ’40-42 16H Norton M/C

[Chris Preston]

'Evening All,

We have a 1940-42 Norton M/C in our museum's collection that we're working on getting back on the road again after some time sitting on display, but it's challenging us every step of the way back to being operational again. The following is in the words of the chap who's working on it:

"It's extremely difficult to start the motorcycle. The engine will turn over easily and appears to want to catch but won’t engage without difficulty. Continuous adjustments with fuel, advance and air have little effect but engine will backfire occasionally when trying to start. Lately, the backfire is getting very noticeable. Spark is good but plugs show carbonization. I suspect mixture is lean but backfire suggests rich? However, when the motorcycle does start (once every 5 min and 50+ kick starts) it runs very well for 20 sec before stopping. No amount of throttle adjust/control will keep it running. For those 20 sec of running it sounds very good and the bike can be revved with throttle. But at the end of that 20 sec it simply quits.

Spark appears good, and the points were adjusted and spark is good, but I am not convinced that the advance/retard setting is correct - movement is free, but seems to only go half way. Compression is good; gas is good, and so are the oil levels."

Any advice would be greatly appreciated.

Sincerely,

Chris Preston,
Ashton Armoury Museum,
Victoria, BC, Canada

[pauldavies]

Hi Chris and from the get-go I will admit to knowing nothing about two wheeled devises but your problem sounds like fuel starvation, I have had the same issue with my C8 in the last week as you. Got the thing started after a lot of turning over then up the road till it just died after 10mins, left it a while then restarted and away I went but popping and backfiring all the way till again the engine died. This went on all the way home, on investigation I found the manual fuel pump wasn't drawing enough fuel for the engine to keep running. This was due to a 12v fuel pump I had installed but had left in the system so I removed it and all was well. The 12v pump was drawing too much fuel so I stopped using it due to backfiring so too much fuel and too little fuel has the same effect, look at your fuel system as there is a blockage somewhere.
Paul

[jeepfinger]

Hi Chris,

Have you tried on Henk's site? Here is a link to it.

http://www.wdbsa.nl/

There are very knowledgeable folk on it, i'm sure that they will get it sorted for you.

Dave

[Ron King]

Back fire is usually weak fuel mixture.

[45jim]

http://www.wdnorton.nl/Running_a_16H_or_Big4.htm

Damn simple bike but you must get the simple stuff like ignition timing, carb set up and magneto all checked out and working properly. No short cuts.