A10 Noisy and running rough

[Marka10]

A10 Noisy and running rough
My A10 has started to be noisy and running rough after been ok for 800miles.
It is banging when firing, very loud.
It is fitted with an electronic ignition (Thorspark 6 volt) which seems to be set correctly at 11/32 of TDC. The compression is the same on both cylinders 100psi 7Kg/cm and the valve clearances are correct.
It is as new Amal Carb and I have tried draining and refilling the petrol tank.
Can anyone give me some direction?

[A10 JWO]

Banging when firing sounds like timing is out and firing via the valve(s) causing poor running.

[Marka10]

Hi
Thanks for reply,
Timing is what I first thought.
So checked when bike stared running rough and noisy, I was riding the bike when something changed and it started running like this.
so checked timing looked ok from when I first set up the electronic points.
Also I have manual Advance and retard so I can adjust timing with lever.

set timing several times but made no difference so replaced electronic points and still made no difference.

So run out of ideas.

Cheers

Mark

[Marka10]

photo

[JulianS]

Check the timing with a strobe light, you cannot do it with accuracy using a measuring stick.

[Marka10]

Hi Julian

Good to hear from you again.

Should I use a timing wheel on the crank shaft primary side to mark the advanced position and check the firing with the strobe.

Cheers

Mark
 

[JulianS]

Mark

If the timing is significantly retarded the engine will lack power and tend to overheat, if too advanced it will probably pink. It wont run happily in either extreme and the exhaust note may sound a bit off.

The issue with electronic is how to identify the exact position the unit fires the coil. Thats where the strobe comes in. I think the Thorspark instructions say strobe it. One degree out at the magneto end gives you 2 degrees out at the crankshaft.

My A10 has a Boyer setup and I use an SRM cush drive nut which takes a degree disc and a piston stop to identify top dead centre but I am sure you could improvise. If it checks OK at least you will know that the timing is OK.

I set my alloy head high comp A10 at 34 degrees full advance.

The dual output coils can get quite hot so advisable check that it can dissipate heat OK.

[Marka10]

Hi Julian
Checked the ignition timing this weekend using method you advised (see Photo)
Set up to 30 degrees from TDC using strobe
Starting first kick but still running rough and back firing.
Seems like valve timing.
Not all the petrol is been burnt, can the valve timing move, the bike ran fine for 900 miles since it was overhauled and I got it.
I helicoiled the spark plug threads, went for a test run after ran ok for half mile then started running rough. (cannot see connection with helicoil?)
I have done the following-
Taken head off checked valves
Checked compression- both cylinders about 100psi
Swapped the electronic ignition.
Checked valve clearance
Emptied petrol and refilled
new plugs
new plug caps
Swapped Carb

Any thoughts

Cheers

Mark
   

[JulianS]

I think 30 degrees full advance a bit too retarded.

I run my alloy head high comp A10 at 35 degrees full advance.

Valve timing will not change during running.

What was done during the overhaul?

Is the carb flooding? Or jets or slide the wrong size?

[Marka10]

Hi Julian

Thank you for replying,

I triad the advance from 30 to 40 degrees, it became difficult to start at 40 degrees.

Its now set at about 32 degrees

I am not sure what was done at the original overhaul, the chap who did it passed away and I bought it fro someone who bought it from the chaps son.
very little information.

I got it in May 2017, I got it running on the magneto but difficult to start, so I fitted electronic points and bought a replacement Amal Carb.

it has ran well since fitting new carb and electronic points, done about 700 miles last year


Engine seems good - No noise from bottom end of engine, pistons look new, vales seated ok- when I had the head off.

Problem started after the spark plug thread stripped and helicoil.

Tried the old carb back on still same problem

Did a lot of work on the body work over the winter so cheesed off that I can not show it off

Cheers

Mark

[Marka10]

back on the problem after holidays

I now think that the problem is not all the petrol is been burnt on the firing stroke and because I have the Thorspark  electronic ignition which fires on both the compression stroke and the exhaust stroke (sacrificial spark) the surplus petrol is igniting on the exhaust stroke.

Problem stared after Helicoiling the spark plugs, not sure if this is related

Any thoughts on this.

Cheers

Mark

[chaz]

we use helicoils every day, can you check the coils are airtight, plugs in and soapy water around.
personally, I wouldnt helicoil plugs I would have had tried to reclaim by bushing and remachining.
I see this has been a while, you have drained tank etc, have you had carb cleaned ultrasonically? Im currently working on a bike where the fuel has eaten away parts and corroded the brass jets.ethanol!!
is a plug and or plug cap breaking down?

[Marka10]

Chaz

Thanks for input

Going to check everything again, start from scratch -
Valve timing
valve clearance
ignition timing
Check seal on plugs, has you suggested. put plugs in a kick over with soapy water around plug.

The carb is a new amal monoblock

I am sure its something simple

cheers

Mark

[Mike Farmer]

 

Quick thought. Do you have any residue in the exhaust pipes. If so what colour etc. Sounds like you may have something as simple as a mixture problem???/As I say just a thought.

Mike

[Marka10]

Mike

Thank you for input, not notice any residue in exhaust put not looked. The bike has does run rich. will check this once I have set every thing.

Set valve timing do I just align marks or its there anything else to set.