1953 Plunger A10 starting woes

[DAVE BRADY]

Hi John,

I would say that there is still a problem with fuel.  Assuming that you 'tickle' the carb to cause a rich mixture for starting, the initial rich mixture is firing as would be expected but this surplus is quickly used up.  There must then be not enough to keep the engine running.
Try firing it up again but keep the tickler down.  This will keep the mixture rich.  If the engine keeps running with the ticker down then the problem is almost certainly with the pilot part of the carb.  Even with enthusiastic cleaning there could still be a partial blockage.   Blow some brake cleaner through the tiny drillings and see if it getting through in copious amounts.  Use the air line as well.  If this fails you will have to poke a thin wire through - not ideal but needs must unless you have a sonic cleaner.  Also, make sure there are no leaks at the carb to head joint.  Do not over tighten the carb. nuts.

Dave.

[johncarter]

Dean mentioned this a while ago but did you check the petrol cap vent hole? I had symptoms very similar to yours on my Norton Model 18 and that's what it was. 

[chaz]

try without the petrol cap on.

[DAVE BRADY]

Hi,

Try without the petrol cap but I would think that a blocked/partially blocked cap would not cause the problem you are having as not enough fuel will have been used to cause a partial vacuum in the tank.  The petrol vapour above the liquid will to some extent pressurise the tank.

Dave.

[BrummieJon]

Thanks for the replies...... I'm using a temporary fuel tank made for the job, not my bike tank....  Leave the lid off every time. I'll try holding the tickler down as you suggest. I replaced then auto advance Bob weight springs and retimed the ignition.... Still the same issue.... When the bike was running before, I didn't have a carb drip plate in place.... I thought it might be safer to have one. However, this has more potential to introduce leaks  so I'll try running it without.
Thanks for your helpful suggestions

[cdsdorset]

Have you checked for air leaks when you removed the drip tray do the mounting studs have a thread free portion?

[BrummieJon]

I haven’t removed it yet, job for next week I’m away at the mo.
My year and model of A10 has the carburettor mounted with bolts rather than studs….

[BrummieJon]

Well, I've tested compression, 100psi on each cylinder which seams reasonable for standard pistons. thanks  I've removed the carburettor drip tray, cleaned out the carbs twice with carb cleaner and an air line, overhauled the advance and retard unit, new pickups and brushes, new spark plugs,
Timing checked again and seems good but it's still no good.... Starts and revs on first kick but still will not run continuously or tickover.....
nothing has changed...
Sticky inlet valve or magneto?

[Matt H]

I know it's awhile, but how did you get on with this? I had a similar issue where are used a brand-new idle jet screw and for some reason it just did not work so went back to using the original one which was significantly better. Also I opened up the points gap to 0.012 and my 350 empire star is running so much better now.

[Mike Farmer]

 

Dont know this particular set up but it sounds a bit condenser.

Mike

[BrummieJon]

After a bout of illness I'm back on the starting of my 53 A10. I decided to change the cap in the mag for an easicap. Easy to do and cheap... much fatter spark and starts OK.... running a bot rough but managed together it ticking over, all sounds good... I noticed that one cylinder got hotter than the other... I recon the timing is still off, a bit of popping and banging but it's a runner

[yosemite]

Fitted an easy cap thing to a mag on my douglas 350, after a  few miles wouldn't start, points gap was gone, adjusted gap to find after a few miles the bike started running rough, this time points gap was wider than it should have been, to cut a long story short found that the static point  contact,  the one that clamps the easy cap down,  was for want of a better description moving which affected timing and spark. Ended up having to completely strip armature and put in a proper condensor. Dont know if it was me not tightening the screw down enough but after rebuilding the mag using the original parts there was no problem with the bike, at least there wasn't till the big end roller cage  collapsed.

[BrummieJon]

I'm getting there, it ran better (but still a bit rough) after fitting an easycap to the magneto. Got it to tickover but stalls a bit when opening the throttle but runs with a few bangs at higher revs, bu8t its better than it was.. The rocker box leaked so I've taken it off and treated it to some copper gaskets. I managed to refit it ok, using the comb to guide the pushrods back in and all seems to be operation fine, I even got it to run but the timing was way out this time. I'm not happy about one of the inlet rockers the tappet sits much higher than any of the others... I think that its working on the rocker and operating the valve but maybe not properly seated in the rocker cup, I don't want to remove the rocker box again, has anyone had any luck reseating a stray pushrod without removing the rocker box?

I'm thinking to loosen off the tappet and trying to manoeuvre the pushrod into its seat but I cant see a thing.

[BrummieJon]

An update to this post... It's now been three years since I posted... I tried everything, rebuilt mag fitted easicap, cleaned the carb numerous times. New jets. Many attempts at timing... Always the same... Starts first kick, revs then dies.. nothing would make any difference...ended up buying a brand new Amal carburettor... Problems sorted, first kick, runs beautifully.. Thanks for all the helpful comments but the only solution was to chuck some money at it lol... Now to sort out those oil leaks..