Author Topic: 1956 BSA A10 RR USA spec. Timing gears Setup.  (Read 2561 times)

Offline Minto

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #15 on: 28.08. 2021 22:27 »
Reeeeeesult!
 *smile*
52 A10 plunger
Aprilia RSVR

Offline edboy

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #16 on: 30.08. 2021 20:57 »
you said you had gas at the plugs and nothing popped or banged.
with compression , fresh petrol in the bore and a spark i would have expected something.
strange.

Offline thackero

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #17 on: 04.09. 2021 00:56 »
ARGGH The following day nothing. Thought it could be wet sumping. Drained excess oil from the crankcase. Not firing and no sign of life. Took carb off and fitted it to my spitfire which started on first kick. Back to timing. refitted carb. Not ready to give up yet but I am close !!!

Offline Joolstacho

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #18 on: 04.09. 2021 01:24 »
Magneto!
Have it reconditioned.

Offline thackero

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #19 on: 04.09. 2021 16:18 »
Magneto has been reconditioned :(

Offline Swarfcut

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #20 on: 04.09. 2021 17:31 »
  Thackero.   So it ran, then nothing?   Something  could have slipped or settled. My feeling is the magneto is the place to look. Even with faith in the reconditioned unit, a quick look at the simple stuff is well worth a go. Try it first without the points cover cap. An unintended earth grounds the magneto, no sparks at all.

   I'd check the earth brush by the nameplate is all good, likewise the pick up brushes nice and free, running on a clean slip ring. If a steel points backplate make sure it has been set up for clockwise rotation at the points end, and that the spring blade does not touch the cam ring. Early type Brass breaker points come as clockwise or anti-clock variants. In all cases the pivot point leads the fibre heel as the armature turns. So, are they the right points, clean, gapped and electrically and physically sound and correctly located and tightened down onto the armature taper?

 Centre points bolt also has to be the correct one for the points used, they are different lengths, brass type also has a taper under the head. Points have a fine key location to the armature, make sure this is in order and when fitted and tightened in place the points plate rotates without wobble.

 Always set the points gap before setting the timing.   Correctly fitting the plug leads is easy, a cylinder coming up on compression, points just opening, brass segment on the slip ring is visible "down the hole". This plug lead goes to the cylinder on compression.

 A good strong spark in the right time and place, a swig of Start You B**ta*d and you should get some sign of life. If not, there is something mechanical slightly awry. Magneto drive gear goes on the magneto armature positioned with points just breaking.  Manual magneto set to full advance, if an ATD unit, wedged open, also to give static timing at full advance. Crank position set as specified, timing gears loaded backwards to eliminate backlash and simulate driven condition.  Usual problem here is the drive and armature move as the retaining bolt is tightened, so first settle the gear on the clean, dry taper with a gentle tap, not a big smack which can be expensive.

 This link may help if you have to dig even deeper.     https://www.a7a10.net/forum/index.php?topic=5549.msg37740#msg37740

 Thanks expressed to Musky for the additional link to useful stuff.

 Swarfy.


  Additional. Reading back through the original posts this engine has run just once. Aim for regular firing on start spray before worrying too much about the carb. Even the best carb is useless without mechanical and ignition systems set correctly and in working order.

Offline thackero

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #21 on: 14.09. 2021 01:03 »
The latest is that I appear to have the wrong length pushrods. mine are 8 3/8" and 9 3/8" they should be 8.5" and 9.5". Ordered new and rocker cover is presently off. One of the pushrods also may have popped out of its rocker arm pocket. I am not beaten yet !

Offline thackero

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1956 BSA A10 RR USA spec. still not running :(
« Reply #22 on: 09.11. 2021 03:43 »
Update. new pushrods.rebuilt carb retimed again. pop bang then nothing. suspect mag. back to being fully rebuilt by a mag expert.gears all in the correct position. last time i buy a basket case !

Offline Swarfcut

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #23 on: 09.11. 2021 09:45 »
 Before you take off the magneto, mark the points housing with the position of the fibre heel with the points just breaking. With the plugs out, turn the engine and feel for compression on both cylinders. As the piston comes up on compression, check that it continues to rise as the fibre heel approaches the mark. Magneto must be set at full advance, easy with manual maggy, with an Auto it's timing cover off, auto unit wedged. If it goes over TDC before the points break, there's the problem.

 This enables a quick check on the timing and by viewing the slip ring tells which lead goes to the cylinder about to fire. It also tells you there is reasonable compression and that mechanically you're in with a chance.

 Folks have mis-timed these engines to fire AFTER Top Dead Centre, so no go. Whatever the timing is set to, the magneto should produce a reasonable and regular spark from both leads. Try with the magneto cap off, these are notorious for un-intended earthing and consequently no sparks.

 Swarfy.

Offline thackero

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #24 on: 01.01. 2022 14:27 »
Update. Magneto rebuilt. Engine timed. Ran for 5 minutes oil returning to tank and circulating fine. Found a crack in my mono bloc carb nozzle body so swapped the 376 out for a 389 mono bloc. will attempt to start it again today and set up the carb.

Offline thackero

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #25 on: 03.01. 2022 01:43 »
389 carb fitted . would not fire. took the carb 389 off my a10 spitfire and fitted it to the rr still would not fire. maybe the fiber timing gear slipped on the mag tapered shaft. nice spark at plugs. maybe the crank gear on the timing side behind the oil pump has sheared its key. just a thought as i am lost with this one !

Offline CheeserBeezer

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #26 on: 03.01. 2022 05:04 »
A bike that runs for a few minutes then stops could be a victim of poor quality magneto brushes. It would be worth taking a pickup off and cleaning the slip ring very carefully. Then replace the brushes with old, original Lucas ones. These can be identified by a thin groove along their length.

Online Triton Thrasher

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #27 on: 03.01. 2022 09:45 »
maybe the fiber timing gear slipped on the mag tapered shaft. nice spark at plugs. maybe the crank gear on the timing side behind the oil pump has sheared its key. just a thought as i am lost with this one !

Don’t just wonder about it.  Check the ignition timing.

Offline thackero

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #28 on: 25.01. 2022 19:32 »
So had the Beeza running on easy start fuel after resetting the ignition timing again then it stopped and now with the fuel tank on  nothing. Plugs seem dry so back to the pilot circuit in the carb.

Offline RDfella

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Re: 1956 BSA A10 RR USA spec. Timing gears Setup.
« Reply #29 on: 25.01. 2022 19:44 »
Cannot understand why this engine needs its timing reset on a weekly basis. As for starting on easy start then stopping - how old is the fuel in the tank? If more than a couple of months, dump it and put fresh. Modern fuel only lasts a few months, after which the volatile elements seem to have departed, and with it any chance of starting. DAMHIK.
'49 B31, '49 M21, '53 DOT, '58 Flash, '62 Flash special, '00 Firestorm, Weslake sprint bike.