Author Topic: A10 rough running after rebuild  (Read 499 times)

Offline billj1800

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  • BSA A10, Moto Guzzi Sport 1100
A10 rough running after rebuild
« on: 24.08. 2016 12:35 »
I have just completed a very long rebuild - 1979 until the day before yesterday.
I have been riding around the paddock to get the feel of it.
It has new plugs, points and fuel.
Started off fine - started easily, ran and idled smoothly.
After only a couple of miles it is:
- kicking back on starting,
- surging,
- idling rough,
- has very black plug electrodes,
- now won't start at all.
A number of queries have come to mind:
- can the timing go out so quickly?
- could the auto advance be stuck?
- can the carby become un-tuned so quickly?
I am betting on ignition but it may be fuel I guess
Any suggestions on where to start?
I would appreciate some help.


Online RichardL

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Re: A10 rough running after rebuild
« Reply #1 on: 24.08. 2016 14:44 »

Welcome to the forum.  *welcome* It certainly would be interesting to hear how the rebuild took such a long and winding road. Also, pictures are always appreciated. I see you are in WA, but not sure how close you might be to any of our members who might be able offer direct help.

Kicking back makes me think it's about timing becoming too advanced. Maybe the springs in the ATD are bad, maybe the ATD gear is stripped, maybe the ATD was not properly tightened on the taper, maybe the locating tab on the points is shmeared off, maybe the locknut on the points screw was not tightened and, finally, maybe it's none of these. It sounds to me like investigating under the timing cover and retiming are in order, but let's wait to see if there are  some other ideas that don't require any dismantling.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at for details.

Offline muskrat

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Re: A10 rough running after rebuild
« Reply #2 on: 24.08. 2016 21:06 »
G'day Bill, welcome to the forum.
Richard's suggestions do have merit.
 Surging rough idle indicate lean mixture, black plugs indicate rich mixture or burning oil  *doubt*. Combining the two leads me to think inlet valve guides (sucking oil and crankcase air). You may also have the tappets set too tight so that they ride once the motor warms up.
What year model? Which carb? Manual or auto advance?
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Muskys Plunger A7

Offline Peter in Aus

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Re: A10 rough running after rebuild
« Reply #3 on: 25.08. 2016 13:56 »
Hi Bill, welcome to the forum *welcome* I'm just up the road a bit, Busso PM me, we may be able to catch up and give you a hand to sort it out.

Busselton West Australia
49 A7 longstroke
58 A10  SA