Author Topic: A10 Not starting  (Read 670 times)

Offline owain

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A10 Not starting
« on: 18.10. 2018 10:46 »
A couple of weeks ago I managed to ride my A10 300 miles to London and back. The next weekend the bike stopped working whilst out for a short a ride. I managed to get it started by running and dropping the bike into 2nd gear. A few weeks have passed now without any riding. I tried to take it out for a ride last night but it was showing no signs of light whatsoever.

I've checked that I'm getting a spark with timing is set at 11/32" BTDC and I've got good compression in each cylinder (150PSI in both). The only thing that I can think are an issue is carburettor set up or the fuel has somehow become contaminated..

I'm running an old concentric carb on the bike with 210 main jet, 106 needle jet, 40 pilot jet. I'm wondering whether to resort to place the original leaky remote float amal carb back on instead? Any other ideas of what could be a possible issue?
Sweden & North Wales
'50 BSA A10
'69 BSA A75R

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Re: A10 Not starting
« Reply #1 on: 18.10. 2018 11:27 »
 Owain.. Back to basics. Fault is Mechanical, Fuel or Ignition. Go for the easy stuff first. So, your mechanical check  rules out anything catastrophic. You have a spark, hopefully in the right place so you are right to suspect fuel. Before you rip it apart, try a spray with Easy Start, known otherwise as "Come on you  ba****d.. If it fires up for a few seconds, it is more likely a fuel issue. No change, still won't go, then start with a check on the ignition. Try maggy cover off to eliminate unintentional grounding, check points gap,  clean the slip ring, pick up brushes, check plug leads on right way round.  Then check the timing. All  OK? Then start on the fuel system. 

 Swarfy.

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Re: A10 Not starting
« Reply #2 on: 18.10. 2018 12:32 »
There's an old saying that goes something like 'most carburetor problems will be found in the ignition system'.
Having said that, have you tried fresh fuel? Modern fuel, if over three or four months old, will simply not fire. You may well start it on easystart and then it'll run on the old petrol, but you won't start it on that cr@p. When I was a lad in late 50's early 60's you could pull an old bike (or car) that hadn't run for several years out of a shed and start it. Now, no chance after just a few months. Which is why after a run I turn the fuel off and let the motor run dry. That way at least I've got fresh(ish) fuel to start.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online Greybeard

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Re: A10 Not starting
« Reply #3 on: 18.10. 2018 13:12 »
Do the plugs show signs of petrol being present?

Offline worntorn

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Re: A10 Not starting
« Reply #4 on: 18.10. 2018 16:08 »
You might have a weak mag which is showing  spark at the plugs when checked at atmospheric pressure, but the spark dies when under compression.

Glen

Offline trevinoz

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Re: A10 Not starting
« Reply #5 on: 18.10. 2018 21:29 »
Have you cleaned the pilot jet?
It won't start if it is blocked.

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Re: A10 Not starting
« Reply #6 on: 18.10. 2018 21:45 »
40 pilot jet?

You sure?

Offline owain

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Re: A10 Not starting
« Reply #7 on: 19.10. 2018 19:01 »
Cheers for the good advice. I'll spray some starter fluid into the to see if i can get any life out of it. I just re-checked the ignition timing about 2 months and ago and was happy with it being spot on. Plus the magneto was reconditioned this summer at APL magentos. Good point about it not necesarily sparking under compression, although I checked for a spark using a 'spark plug tester' that showed a bright red flash when a spark was generated under compression.

Definitely a .40 pilot jet (and that is running too lean as well!) I took the carb apart to fit, what I thought was a larger .30 pilot jet but was shocked to find that it had already been running a .40 jet.
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Online edboy

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Re: A10 Not starting
« Reply #8 on: 19.10. 2018 19:31 »
first thing i would check is valve clearances. no compression means no big bang.

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Re: A10 Not starting
« Reply #9 on: 20.10. 2018 06:39 »
G'day Owain.
The large (than usual) pilot jet may be to mask a worn slide or air leak by the previous owner.
Cheers
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Re: A10 Not starting
« Reply #10 on: 20.10. 2018 10:27 »
 Hi all, just following this thread to see if owain has got it going.

  I suggested checking the timing.  This is easy with a manual maggy,  just put on full advance and check points opening with piston height in the time honoured way.   With Auto advance to do it properly and wedge the auto unit on full advance will require a bit of hassle and mess. So, has anyone ever measured the piston height when the points are breaking and the auto unit is (hopefully) fully retarded, on a well set up motor?  In the old days, car ignition timing was usually set statically, dizzy weights in the fully retarded position.  Ok, not a true check of the running state timing, but a good enough check that nothing is drastically out of order.

  Interesting to see if anyone has done it.

   Swarfy.

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Re: A10 Not starting
« Reply #11 on: 20.10. 2018 10:37 »
G'day Swarfy.
I did 20 or so years ago but can't for the life of me find where I wrote it down. From memory (not a good indicator) it was only a few degrees btdc or 1/32".
My rule of thumb is to advance till it pings then back off 2-3 degrees  *bash*
Cheers
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Re: A10 Not starting
« Reply #12 on: 20.10. 2018 10:52 »
 
Quote
....With Auto advance to do it properly and wedge the auto unit on full advance will require a bit of hassle and mess..

 To do a simple check is possible to just hold the points plate in 'advance' mode....works for me- generally, but don't do it unless I need to...

 
Quote
......So, has anyone ever measured the piston height when the points are breaking and the auto unit is (hopefully) fully retarded, on a well set up motor?  In the old days, car ignition timing was usually set statically, dizzy weights in the fully retarded position.  Ok, not a true check of the running state timing, but a good enough check that nothing is drastically out of order.

  Interesting to see if anyone has done it....

 Musko got in while I was tapping

 Funny you should ask, and I'm glad you did because I'm too lazy, but seems logical (and intended to do it but forget), as when I check my Gutzzly timing every few years, I do it just like that...(easy after I pick the right marks out of a zillion on the flywheel)...I have also used a timing light, but aligning the full advance marks needs to be ~>lotsa rpm and is VERY loud....so don't bother


Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Re: A10 Not starting
« Reply #13 on: 20.10. 2018 10:53 »
  Musky, that's how we did it in the days before timing lights, and still do on my old Ford Clanker. Gives the best performance on current fuels and it is good that you can still adjust the old time dizzy.  ECU's and all the other electronic miracles  are great when new, but failure means everything, including the value of your ride, drops to zilch when the happy dealer wants almost its current value to put it right.  " Sorry Sir, you need special equipment to set up and reprogram. It will be 7-10 days for it to come from China" We can't guarantee it"   Time then to raise a second mortgage. 

   If it ain't broke........

 Swarfy

Offline owain

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Re: A10 Not starting
« Reply #14 on: 23.10. 2018 19:10 »
Cheers for the tips. I put new fuel in and managed to start it up but it's running very rough at idle. Checked valve clearance and that is fine. Timing should be ok as I set it at 11/32" btdc in full advance (I have that auto-advance unit). I think I'm going to swap the concentric carb back to the remote float as the concentric carb is giving me no end of problems. I bought it from an auto-jumble and replaced the jets but I think musky might be right to say that it's got a worn slide/ leaking air :/
Sweden & North Wales
'50 BSA A10
'69 BSA A75R