Non-starting VB

[john.whiting]

Is your carby ok.Is it rebuilt ,or was it" good enough" to go back.Loose slides and worn spots at idle make engines very difficult to start.The other thing I always try is a whiff of Aerostart.This cuts out all the mixture problems,and requires only correct cam and ignition timing.Often a carby thats otherwise ok will block a small passage if left unused,and the suction from the engine starting on aerostart will clear it out.Out here,the brand of spray I use is called "Start Ya Bastard" which sums it up.Regards John.

[john.whiting]

One more thing,make sure there are no suppressed/high impedance components in the ignition system.Regards John

[dave.owen]

From the primary side looking at the mag the advance cable should exit to the rear. This is a tight wire advance.

Dave

[nevhunter]

Magneto's don't like suppression ignition leads. You must retain copper wire HT leads or you will goose the windings. Nev

[simon.holyfield]

Magneto's don't like suppression ignition leads. You must retain copper wire HT leads or you will goose the windings. Nev

And no surpressors in the plugs or caps!

[nevhunter]

Indeed and no eccentric slip rings etc. Nev

[ColinPeck]

Although there's many reasons why an engine won't run properly there's very few which stop an engine actually making an effort to run. A tea spoon of petrol down the plug hole, open throttle with no choke will start anything with a carb issue, unless of course the carbs flooding but that would be apparent by the pool of petrol coming out of it. I've started a few engines with no carb at all, just petrol down the plug hole or a squirt in the inlet.
So that leaves compression, easy enough to dismiss simply by kicking it over, spark or valve and ignition timing. Even if it's the wrong camshaft, if it fits in the engine it would be somewhere near enough to have it firing.
Assuming you've checked it actually has a reasonable spark that only leaves the timings, spitting back through the carb sounds suspiciously like valve timing. Every 4 stroke engine has both valves rocking at TDC on the non firing stroke, by rocking the crank a little each side of TDC you should see the exhaust closing and the inlet opening when it's rocked in the correct running direction. Also make sure the points are NOT opening on this stroke.
I've recently had a play with a 1902 Ormonde which the owner had the engine apart and re-assembled. After pushing it down a hill to fire it up with no joy I asked him if I could check things out. Although the cam timing was set by someone who had lined up the poor timing marks, when I checked the exhaust valve timing with the piston at TDC non firing stroke (atmospheric inlet valve so not a lot of help!) it showed the valve timing to be wrong. Re-timing the cam and then the ignition to suit the new cam position, a squirt of petrol down the priming valve and off she went. Still carb issues, inlet air leaks and other things to sort out but she still fired up.
Good luck
Colin

[Roger.Baker]

Try changing the plug. I had just this with a Rudge Ulster, spitting back through the carb; after 2 months rebuilding carbs etc and checking timings, a friend said " have you changed the plug ", so I did, just to prove what a silly idea that was. The thing has run fine ever since.....

[paul.jameson]

A vast amount of excellent advice has now been issued, but I see no response from the owner of the offending VB. Could it simply be that you had forgotten to turn the petrol on? Please report.

[nevhunter]

He may be overwhelmed. Nev