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?
Banging when firing sounds like timing is out and firing via the valve(s) causing poor running.
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
photo
Check the timing with a strobe light, you cannot do it with accuracy using a measuring stick.
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
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.
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
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?
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
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
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?
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
:) :) :)
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 :) :) 8)
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.
Hi - sounds to me like a weak mixture, something like the pilot screw adjustment or a blocked pilot jet. What carb are you running? If it is a Concentric the pilot jet is actually a bush which is difficult to unblock. You have to drill through the other side and unblock with a piece of wire (crude I know) and then tap the drilled hole and screw in another shortened pilot screw to block the hole.
John.
Hi John
Thanks for your input,
I now think the original Problem is the petrol mixture. To satisfy myself and increase my knowledge I am going to set valve timing, valve gaps and ignition timing.
I will than know all this is correct and try running again.
I was thinking the mixture is to rich and not all the petrol is burnt on ignition stroke and because electronic ignition fires on exhaust stroke, on each piston (sacrificial spark) I am getting firing on the exhaust stroke.
Cheers
Mark
:) :)
Maybe something as simple as loose manifold nut/s
Mike 8) 8) 8)
seems to me there is a lot of people suffering fuel problems, common fault misfiring and poor running. we straightaway assume the bike has a problem despite our regular tinkering,makes me wonder if its down to the fuel. As ethanol has been widely discussed over the last few years its dropped back off the radar recently.
a couple of my Brits have problems, the Jap stuff gets used more often and fuel turned over but I see many carbs that have corroded brass parts while overwintering.
as some have problems with fuel evaporating (tufnol spacer discussion) , modern fuel is upto 15% ethanol which absorbs water, this could be vapourising. also I go back to the days of open fuel storage tanks, working in a garage and common to find pinking as droplets of water banging around in the combustion chamber not being burnt off.
would be interesting to use a octane booster additive or maybe try a tankful of Avgas same as we used to use on racetracks until the ACU deemed racers had to use pump fuel.
:) :)
Back in the day I used a lot of 100/115 AVGAS (occasionally 115/130). On the road A65. But Avgas now is straight 100LL IE 100 octane low lead--no Heptane content. So I doubt that the new stuff would be much of an improvement. I have no idea what the "funny" content is.
Mike 8) 8) 8)
Hi
Thank you for your inputs, can anyone recommend a additive to try.
Thank you
Mark
I have Silkolene ProBoost in the unit, bought for a friend who drives rally cars but outlawed before he bought it...
https://www.silkolene.com/motorcycle/fuel-additives/pro-boost/
Sounds like air leak to me, if it's popping and banging, this did happen to me once , bike running fine then started playing up when I checked I could get a feeler gauge between the manifold.
hi John
just picked up your response, being busy and on holiday.
Still not sorted the A10 problem
where was your Air leak
What were the symptoms
My problem seems to be too much petrol. One plug is getting sooty and one pug is wet with petrol and not firing, this is just after a few minutes.
The Carb is 2 year old all seems ok checked jet sizes etc with Amal, I adjust pilot air, makes a small difference but still runs rough and rich.
Cheers
Mark
Checking valve timing with timing disc
inlet valve starts to open at 60 deg before TDC book says 42 deg before TDC
Anyone had experience of check valve timing
The bike is a A10 1961
Valve timing settings
To set the valve timing correctly you will have to remove both the outer and inner timng cases then pull out the center idling pinion which will have 2 timing marks on it then turn the cam shaft and also the crankshaft until you can replace the idler pinion with all the marks correctly aligned.
The valve clearances for checking timing will be different to the running valve clearances.
Not seen a figure given for the A10 but the A65 figure is 15 thou for checking timing.
If you are checking running clearances suggest reset and check with a 15 thou clearance and see what result you get. It can be difficult to establish the exact opening and closing point.
Hi Marka10,
Long shot - are your exhaust valve clearances too tight?
Is the camshaft the original for the year?
Figures according to Mr Bacon:
1950 only: 015/.015 (67-334)
1951-54: .010/.010 (67-334)
1955-59: .010/.016 (67-334)
1960-62: .008/.010 (67-356)
A10 Super Flash
1953-54: .008/.008 (67-356)
A10 Road Rocket
1955-57: .008/.008 (67-356)
A10 Super Rocket
1958-59: .008/.008 (67-356)
1960-63: .008/.010 (67-357 probably export only in 60-61, 67-356 for home, used for all from 62)
A10 Rocket Gold Star
1962-63: .008/.010 (67-357)
hi Splodger
I am thinking that when the person who restored the bike fitted the wrong Cam shaft.
I have measured the timing of the valves opening using a dial gauge on the valve stem and deg disc the valves do not correspond with the drawing in B.S.A.Twins W.C.Haywood
The valves seem to be open longer.
The inlet
opening at 60 deg before TDC should be 30 deg
Close at right time 70 Deg after BDC
Could it be wrong Cam shaft?
Can you remove the cam shaft without fully stripping the engine ?
Mark
Hi Mark,
I asked about the camshaft because a too-tight clearance on the exhaust tappet(s) will give you hiccups in the exhaust - popping and banging.
But.... I keep coming back to your original note which read that the bike ran OK for 700 miles or so. Therefore the set -up that you had worked OK with the cam you've got, the valve clearances you had and the carb settings.
So, what's changed?
My suspicions run towards the ignition system you currently use. Perhaps it has a fault? Can you revert to the original mag set-up and see how that works?
Check that vibrations over 700 miles haven't loosened/frayed connections throughout the ignition system, coils and condensers.
As previously posted, rubbish fuel will also give problems. Get some super unleaded or better octane stuff.
Fit new spark plugs as well?
For interest:
Cam IO IC EO EC
btdc abdc bbdc atdc
357 51 68 78 37
366 40 62 67 37
334 30 70 65 25
356 42 62 67 37
Set tappet clearances to .020" to check.
There is a 358 hi-liftcam but that was for US market and/or drag-racing lovers.
Yes, you have to split the cases to get the camshaft out, not a five-minute job!
Hope this helps.
Hi Splodger
Thank you, the all the info and experience is very helpful.
I have gone back to the Mag and points and seen no notable difference.
It is defiantly a over fuel problem. The right plug is sooty in minutes and the right plug get flooded and stops firing.
You are right the bike ran reasonable ok for 700mils but was always very rich even after fitting a new monobloc carb and adjusting needle height and pilot air, made little difference always rich.
But after I Helicoiled the plugs it got worse running really rough and over fuelling, don't know if helicol mad difference.
I opened the inlet valve clearance to 0.015 and it made a small improvement.
Also found some information, amongst paperwork with the bike from the person who did the rebuild, now deceased. He set the valve timing 1 tooth off ??, I set it correct and made very little difference. See drawing.
Not sure where to go next, don't want to strip engine if not necessary, everything sounds ok at bottom end. Compression good and equal on both cylinders.
This is a definitely a challenge, first classic bike, bit frustrated but enjoying learning.
Cheers
Mark
Looking at the valve timing info you posted it looks like I have
Cam 357
Cheers
mark
If you've reset the valve timing after the problems began, did you offset the timing mark as indicated in the sketch?
There has been a similar discussion in the past:(https://www.a7a10.net/forum/index.php?topic=8856.0) which addressed timing marks when an A7 pinion had been used.
Read that topic. I'm reluctant to say that this is the problem because if you reset the camshaft position and it is not correct, you may cause damage - you may not but I would suggest caution.
If you reset timing on the cam by one tooth, take the plugs out and turn her over very slowly to check TDC and valve timing degrees.
Hi Splodger
Do you know the difference between the different CAMs in your list?
will read similar discussion.
Mark
Hi quickly read the similar discussion I think I need to identify that the all the pinions are correct, not sure how to do this?
Mark,
Your pinions must be OK for the bike to run 700 miles.
You did write that you lined up the punch marks on the pinions but you didn't get a significant improvement? But... you've got Inlet opening at 700!
That's not right.
If you line up the pinions as indicated in the sketch you showed, what does that achieve with valve timing figures?
With acknowledgment to A10Boy, 'To avoid a valve / piston interface situation, take out the plugs and carefully set the pistons at the bottom of their stroke. Then turn the camshaft until the dot points to the center of the idler, then turn the crankshaft so the pinion dot is also towards the center of the idler pinion. Then slot the idler back in position with the marks correctly lined up.'
More hassle to do this again but if you can get this set right you won't have to address that question ever again.
If you get the valve timing correct(ish) according to one of these:
IO IC EO EC
btdc abdc bbdc atdc
357 51 68 78 37
366 40 62 67 37
334 30 70 65 25
356 42 62 67 37
.......then you can discard the valve timing as the cause of 'running rough and noisy' and concentrate on the sparks and carb/fuel/air leaks. And, you'll know which cam is fitted.
Dots lined up.
Splodger/Julian
Thank you for information
I will reset the valve timing and measure the valve opening, see picture 1 and see which cam is fitted and get back to you before putting covers back.
They are some numbers on the pinions
Cam pinion - 338
timer pinion - Difficult to read see photo
Cheers
Mark
Photo 1
Timer pinion
Some thoughts:-
Do you know why there are different cam shafts for same machine?
My bike as the alloy head- does this make a difference?
The early 67 334 the standard iron head cam used until about 1958.
the 67 356 was more sporty and introduced on the Star Twin and fitted on the Super Flash and Road Rocket )and the iron heads from about 1958)
The 67 357, the Spitfire cam, came with the Spitfire scrambler and found its way into the Super Rocket and RGS. It was described as super sports cam and gave the engine more grunt, and in my experience gave a bit more valve train noise.
The 67 358 is rare and according to tuning notes not for the A10.
The was also one called the Polydyne sold by Bob Joyner in the 1960s.
The US companys Megacycle and Harman and Collins also produced a number of different A10 cams.
Hi Julian
Interesting, thank you.
Are they all suitable for the A10 Goldflash and the standard carb 250 jet?
Mark
I have used the 356 and 357 in iron and light alloy heads. Both seemed to go OK.
Used 356 with a big valve light alloy head this year and needed a 400 main jet and 3 1/2 slide needle in 3, S and B air cleaner fitted. Only following the Amal tuning guide will establish the right settings for a particular bike.
Only seen one 358 and from memory looked like it had a smaller diameter base circle.
Never seen a polydyne, Megacycle or Harman and Collins nor spoken to anyone who has used one. I would imagine they would be quite rare.
Slodger / Julian
Set the valve timing marks up correctly following the intrusions "A10Boy" Marks on pinions aligned.
Results-
Valve Clearance IO IC EO EC
IN EXH BTDC ABDC BBDC ATDC
0.008 0.010 60 70 90 40
0.020 0.020 50 50 80 30
Any Thoughts
Cheers
Mark
Mark,
These numbers don't match any cam characteristic so I am assuming that your scrap of paper which shows the timing mark to be one tooth removed may be the key to the set-up you require.
So set up the pinions as before - timing marks matched - but now you need to have the camshaft pinion moved anti-clockwise by one tooth without rotating the idler wheel or crankshaft.
Do this by first aligning all of the timing marks. Then, without letting the camshaft move from its position, take out the idler pinion, rotate the crankshaft clockwise (and idler pinion anticlockwise by association) by one tooth and replace the idler.
With the idler replaced, if you turn the crankshaft back one toothsworth, you should see the timing marks aligned between crankshaft and idler but the left-hand idler mark will show as your paperwork sketch indicates - one tooth difference between idler and camshaft.
As before, now check valve timing readings. Hopefully, they will reflect numbers which reflect recognisable values.
Fingers crossed!
I suggest setting the tappets at 0.015 inch and check the timing again.
That is the figure BSA give for checking Super Rocket valve timing in the 1962 Data book. Attached below.
Be aware that the whole of your valve train needs to be perfect condition to get near the factory quoted figures.
Wear on the rocker assembly, the followers, the cam, bearings and bushes and pinion backlash also cause variations. One degree of movement lost at the cam pinion means two degrees out at the crankshaft pinion.
But if it ran OK for the first 800 miles, unless the cam and followers have suffered significant wear in that that time I cannot see that you have a cam problem.
On the compression test - using a simple Gunson tester on my alloy head A10 with Gandini 8.75:1 pistons (actual ratio will be a bit higher as head skimmed due to a warp) and 356 cam - warm engine, throttle open and 4 kicks gives me 160psi.
Thank you for you replies, I will be an expert by the time I sort this out.
I will set valve timing back one tooth (Splodges suggestion) and set valve clearance. 0.015"
see if this gets me near to the Cam 357 (inlet valve opening) 51 68
If problem still exists I will check for Air leaks and contact Amal to check carb components specification
My problem is I do not know what work was carried out during engine overhaul, due to the chap been deceased. so they could be worn parts but everything that a can see seem in good condition Pinions bearing (plain) etc have no signs of wear.
I look at the Cam shaft with endoscope and shows no visual signs of wear and there is no lateral or radial movement on the Cam Pinion
the question is, is the inlet valve opening time, which seem more than the setting effecting the over fuelling.
The compression is good about the same as yours Julian
Cheers
Mark
Mark,
A helpful explanation re difference in A7/A10 crankshaft pinions is attached. Thanks go to cheshirebsa.
hi Splodger
Thank you for information, really helpful.
Checking the bike against infor the pinions are correct for A10.
I think, from the valve openings the cam shaft is a 357 which is from the supper rocket, so I am wondering if the carburettor is correct for the valve opening going to check with Amal.
Cheers
Mark