what could happened???

[emilios]

Hi
My engine died as i was riding...i check and i have gas and spark too...but bike can not start anymore..
What could happened??
The only thing that i can think is that something gone wrong in cylinder head or rockers??
I will open engine next week...i just want to hear if that happened before to someone else..
My bike is A10 Plunger 1953
Thanks

[a10 gf]

Be systematic, can be anything, dismantle engine only after everything else has been checked (unless you have planned to dismantle it anyway).

Sparkplugs dry after a long period of starting attempts, or wet after only a few kicks ? Check carb.
Mag timing ok? Magneto drive pinion\autoadvance loose ?
Points working ok ? Mag kill switch, shorted ?
Still have ok compression ?

And there is the heat thing with older magnetos, when warm they can stop working, spark is back when cooling down. Discussed on the forum.

Good luck, tell us how it goes.

And welcome back to the forum, long time no see! Some A10 pictures from Cyprus very welcome.

[emilios]

 I changed plugs but still the same...points dont look loose but i didnt check clearance...
I check kill switch but its ok..
Compression looks the same as before..
I also check carb and looks ok..
So i will first check  points clearance,next mag pinion,next kill switch wire from mag to switch and then if all this are ok i will start checking engine...i will let you know
Thanks

[RichardL]

Emilios,

Were there any clanking or clunking or other unfortunate noises before the engine died? Regarding points, in one topic here, failure of the keyway in the points is discussed. You said the points don't "look" loose. I don't really know how likely this might be to fail while running, but it would be a non-visible or hard to detect possibility.

Cyprus? I have an upcoming project in Cyprus that will bring me there some time in the future (probably six months or more). Are you in Nicosia?

Richard L.

[Josh Cox]

Hello Emilio,

Lovely bike you have there.

Disconnect the magneto earth lead, this will eliminate a wiring / switch problem.

Try starting it with the reserve tap on.

You can save yourself a fair bit of uncertainty by taking the plugs out, with the bike on the centre stand you can put the bike in gear and rotate the rear wheel.

Stick your finger over the spark plug hole and feel for the four cycles on each cyclinder, suck, compress, depression then exhaust, this can check your CAM timing, valves etc etc, a broken exhaust or inlet valve is unlikely to cause your bike to die, will make it sound like a chaff cutter.

If all appears ok, squirt a little fuel (or use a spray can of ether starter, "start ya bastard" or "aerostart" ) into the throat of your carby and try to start it, if it fires you have a blockage in the fuel system.

There are a few fuel filters possibilities, could be blocked fuel tap filters, I have the same bike as you and it has a AMAL 376 (not standard), it has a fuel filter in the banjo fitting.

If none of the above works, pop the cap off the magneto, whilst turning the engine, check that the magneto shaft is turning and that the points are actually opening, points sticking shut will give you a dead cut, as will points stuck open.

Is your magneto tight, is the timing correct ?.

Dead stop without crunching and grinding sounds is a reasonably good scenario compared to what could happen.....

Good luck.

[emilios]

Emilios,

Were there any clanking or clunking or other unfortunate noises before the engine died? Regarding points, in one topic here, failure of the keyway in the points is discussed. You said the points don't "look" loose. I don't really know how likely this might be to fail while running, but it would be a non-visible or hard to detect possibility.

Cyprus? I have an upcoming project in Cyprus that will bring me there some time in the future (probably six months or more). Are you in Nicosia?

Richard L.

Yes Richard,in Nicosia...just let me know when you will be coming

[emilios]

Hi
I finaly dismalte engine and i found nothing wrong on head like broken valves or springs..
So i think the problem must be the magneto pinion loose.
But i want to ask if this picture of my cylinder with left piston full of  black  'coal' should worry me..and where is problem.
Do i have to change piston rings or something else wrong?
Please advise

[RichardL]

Emilios,

Look carefully at the head gasket to see if there are any obvious signs of oil tracking from oilways to the left cylinder. If not, my inclination is to think it is valve guides rather than rings. How does the left bore look? Any signs of damage? Before you tore it down, did you have good compression that was mostly uniform between cylinders? If the answers are "good," "no" and "yes," in that order, it really seems like guides, however, I bow to several more experienced builders in our forum to correct me if wrong.

Richard L.

[A10Boy]

Did it burn oil, or smoke on that side?

[emilios]

I never notice any smole from either silencers...
Could it be the spark?? not good spark in left cylinder?

Emilios,

Look carefully at the head gasket to see if there are any obvious signs of oil tracking from oilways to the left cylinder. If not, my inclination is to think it is valve guides rather than rings. How does the left bore look? Any signs of damage? Before you tore it down, did you have good compression that was mostly uniform between cylinders? If the answers are "good," "no" and "yes," in that order, it really seems like guides, however, I bow to several more experienced builders in our forum to correct me if wrong.

Richard L.

Left bore looks good,no damages just more black than right one...
I wondering if i can check spark with some way.

[beezalex]

Yes, you can check spark strength with a spark tester and timing with a degree wheel...but just to get it running , you don't need a degree wheel.  You can use the old stick down the spark plug hole method.

[RichardL]

Emilios,

It doesn't look like an ignition issue to me, it looks like charred oil, but others may disagree. Ultimately, your spark on that side can go bad from burnt oil fouling the plug.

Put your plug in the wire cap and let the plug body touch the barrel. Kick over and watch for spark. Repeat the operation, exchanging plugs to see if they perform the same on both sides. This won't give all possible spark information, but it is a good place to start.

Richard L.

P.S. I read Alex's post and, yes, timing must be correct and he is rightly advising as such. Still, maybe first, it would be a good idea to know that there is a spark to time.

[emilios]

Ok so better to put new valve guides and valves to left cylinder..

[RichardL]

First, it would be good to hear some confirmation for the diagnosis from more members. Second, we still don't know if it was a bad head gasket. Finally, as long as you've got the head off, and assuming you're confident about getting them back on, you might as well pull the barrels to get a better look at the pistons, rings, bores and inside the crankcase.

While new guides and valves won't hurt and will probably help in any case, I am a little uncomfortable being the sole (or main) advisor for this work. After all, when I get to Cyprus, I want to come as a friend.

Richard L.

[motoloco]

hi richard same thing happened to my rgs copy ,going well but never as good as my my a10 just stopped dead got the wife to bring trailer out ,took mag back to uk for repair was told slip ring arcing or had fine crack .reinstalled now goes as well as a10 now 1 plug was allways a bit darker than the other which could be your problem with the piston being black. remember reading in forum sometime ago  disconecting 1 lead completly and the bike started.jut a thought .i know what it like richard when you got no mates round the corner to help .but now we got mates round the world .best wishes motoloco alicante