By Al Crusader
I am completely flummoxed. After the engine re-build it ran for 20 miles then refused to start. In the shed for 3 weeks trying everything. Finally today I eliminated every connection and wired the battery to the coil. Very good fat spark at precisely the right time. New monoblock carb set up correctly. The plug is petrol wet and sparking well tested out of the cylinder. Not a single little pop. Why? How? I have checked the timing gears and nothing wrong there. I am obviously missing something or doing something wrong. Any ideas guys?
You say it’s timed accurately but it may be that you’ve timed it on the wrong stroke (there are 2 TDCs). Check both valves are shut at TDC to be sure.
By Al Crusader
Thank you guys. How do I check the compression. Other than with my big boot? And I going to change the fuel, get fresh. I am sure it is timed on firing stroke and will check again but yes this does feel like that's the problem, strangely.
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By Wheaters
Ideally, compression is checked with a gauge which screws into the spark plug aperture. A very basic way to check it is to take the plug out and put your thumb over the aperture and crank the engine. Another way is to screw a piece of kitchen roll up into a tight sausage and screw that lightly into the aperture. Kicking the engine over should force it to pop out.

Obviously, don't drop anything into the engine....

My 350 Bullet kept losing compression. That was caused by a soft exhaust valve seat. Now cured by having a new insert put in.
By Steven hunt
Try checking the condenser. I had loads of trouble with mine ended up fitting a pazon ignition booster to mine since then I've had no trouble with it.
By Al Crusader
Yes I will do a compression test of sorts. The kick start will take my weight for a second, not as good as my 350 bullet but there is compression. I have just fitted new condenser and points, and have another condenser on standby. I don't believe anything any more with this fiasco going on!
By Al Crusader
The mystery is solved;; bad fuel. Not anything clever, just contaminated or stale fuel. I changed that and cleaned out the carb. It fired up after a few prods, and runs beautifully. I feel a bit of an idiot, but hey, it is all learning.
Thanks for all the input.

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