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#63471
Yes, to me it's definitely fuel starvation. I remember years ago when I did aeromodelling that my diesel (compression ignition) engines would invariably start running in bursts as the fuel tank emptied. Short bursts of running are usually caused by the same thing - fuel starvation of some kind. BTW I still have an ME Heron 1cc Diesel engine; I occasionally start it up, just for the lovely smell of ether...
By jefrs
#63472
Never found an Amal's cold slide to be worth much, you hold the throttle open until it picks up. Kevin wasn't firing until the last prod when it caught. Is Kevin magneto or coil? Magnetos have a weak spark at low revs.



If a jet is a bit blocked or a screw has slipped, the motor will generally still start if it has fuel even if it then coughs and splutters. An Amal will sometimes cough and clear itself, but they do have a habit of self adjusting. However the points also have a habit of self adjusting and they do wear in use. Plugs can get a film of water or grease on them and then they won't spark on a cold morning, and HT caps do come loose. Unlike a diesel it must have a spark.
#63474
The reason I mentioned a diesel is that the bike is displaying the symptoms of fuel starvation; the whole point is that there is no spark ignition to play up. Also, in my experience mags play up when hot, not cold. I have left my Tiger 100 for six months and it always starts first or second kick, then may die if the revs drop too far. If it were the mag it must be a self-healing special 'cos it works fine now according to Scalyback. It' was a fuel related problem.
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By Exile
#63475
I couldn't help having a little giggle.. Jefrs.. Quote:


"Kevin wasn't firing until the last prod when it caught."


Yep. No matter how many times you have to kick 'em over, it's always the last one that does the trick... :-)
By Gwilly
#63477
I agree with Dennis, If the night time temperature in the garage is dropping to single figures then you will probably need choke for morning starts..

My 59 Norton was a bit recalcitrant and i used to find priming with the tickler and then closing the air slide (choke) completely would get the motor running with a kick or two..

After a few seconds running you may find the motor starts to 8 stroke and sound rough, thats when you ease open the air slide towards half way as the motor starts to sound more even firing..

Don't be in any hurry to ride off but let the motor warm a little till it will take throttle without cutting out..

When on the move you can then open the air lever right back but don't use more than half throttle until the motor is well on its way to normal running temperature..

Having said all that it may be prudent to check out the points for pitting and gap, HT leads and caps, also inside the distributor cap for dampness, clean the rotor arm and spring pin in the centre of the dizzy cap..

With everything sound i would give the cap, HT leads and plug caps a good spray over with WD40 to help water proof ready for the winter..

regards gwilly.
#63478
Kevin is coil.



I will have to move the position of the air/choke lever a little as it seems it was not designed to actually work. I guess the restorer did not need it.

Thanks for your time and all the ideas guys. It will be mid December before I return to France, but I hope that some of this advice will answer the question.



I will give an answer when I find out!
By jefrs
#63485
Exile, I do appreciate the humour in, "you will find it in the last place you look", but to my ear Kevin doesn't actually fire until the last couple of prods after reseating the HT caps when it then starts. Firing and starting to run not being the same. Before that K makes the usual 'flobber' whilst being spun by the kick but doesn't cough. Like Gwilly also suggested, I would start with the sparks.



The Amal cold start is a crude thing, a slide that drops down blocking the air flow, but without air flow the main jet produces less fuel, it's almost self-defeating, hence lifting the throttle to raise the idle whilst warming up. And flooding the carb on the tickler of course.

Rule of thumb stuff - If you have petrol from the tickler it is going into the motor and it will fire on it if you have a spark. If the jet is blocked completely you get a firing bang but it won't run. If the jets are furred up it may run badly but it will fire the fuel. Petrol itself is a pretty good solvent, it may clear the jet itself.



I am not suggesting a faulty magneto but the nature of these things is they do produce more volts when spinning fast and hence poorest sparks when spinning slowly, at start up. Almost anything, like an iffy connection at the HT cap or dew wet HT leads can prevent the bike starting. Once you get the first fire down a cylinder it spins faster and makes bigger sparks. Another thing to consider, it's morning, we get condensation then, which doesn't help the sparks.



I'd start with the spark plugs and work back up the HT line, clean and reset the plugs, tighten and clean their connectors, check the HT cap connection, Kevin's HT leads are rather long, check distributor cap for cracks and clean it (no oil inside), check/clean rotor arm. Leave a magneto well alone but do check points and condenser (as applicable). This is easy stuff, so do that before stripping the carb down (although an Amal can self-adjust the idle and pilot screws, reset).

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