Author Topic: A10 Running Lumpy  (Read 319 times)

Offline ALPH1

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A10 Running Lumpy
« on: 03.10. 2019 11:56 »
After new rings and breather washer replacement the bike was running VERY lumpy. I quickly noticed that the left pipe was a lot colder than the right having me thinking it was either missing or not firing at all on the left. Checked compression (thumb in hole) ok not scientific :) but it did seem good or the same on both sides. Check for spark and it seemed very weak. Swapping plugs I could see that both the plug and lead were poor on the left. So, new leads and plugs ordered but while waiting. I noticed that the carbon rod see pic is missing off the lead end that plugs into the mag. Has this fallen into the mag and could this account for the lumpy running

I really though it was the carb and have ordered new jets. I have the needle on the last grove and that improved things but did not fix it.

Symptoms:

carbon and fuel blowing out of the carb
Lumpy running
Some black smoke
fouled plugs/sooty     
rough idle 

My biggest fear is the rod has dropped into the mag and its causing a miss.. Is this even possible. My gut is telling me its the carb but it did run before with this carb and jets without this issue.

Thanks

Al


Offline Swarfcut

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Re: A10 Running Lumpy
« Reply #1 on: 03.10. 2019 13:11 »
Minto is the expert here...exactly the same happened to him recently, and he was lucky enough to find the carbon brush lying loose under the slip ring. Have a look in the pick up...the brush retaining  spring may be still in there.  If not looks like a quick maggy strip and clean. Check the earthing brush under the brass slotted screw next to the Lucas Nameplate....this is often neglected.
Swarfy.

Offline ALPH1

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Re: A10 Running Lumpy
« Reply #2 on: 03.10. 2019 13:39 »
Thanks Swafty:

Is stripping the mag and big deal.. I thought I read Id need a pinion puller or was that on the timing side, cant recall. The service sheets are not very clear on the dismantling. 

Al

Offline Clive54bsa

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Re: A10 Running Lumpy
« Reply #3 on: 03.10. 2019 15:43 »
Although, the carbon brush falling inside the magneto is obviously a problem that needs to be fixed, the description of the symptoms you have
"carbon and fuel blowing out of the carb
Lumpy running
Some black smoke
fouled plugs/sooty     
rough idle"
comes right out of the BSA A10/A7 workshop manual for a overly rich fuel mixture.


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Offline Swarfcut

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Re: A10 Running Lumpy
« Reply #4 on: 03.10. 2019 16:24 »
Al, you can see from your good pick up that the carbon brush is spring loaded, so you need to account for the spring and the brush. The spring could still be in the pickup, or in the magneto. So first thing is a good look, torch/mirror trick, next a piece of rag or paper towel worked in and persuaded round the slip ring....this should find the remains of the missing parts  with a bit of luck.

If you have no success, but are sure the bits are in there, then the end housing needs to come off, for a good look inside. With no primary case on the engine this can be done, but the usual way is to remove the magneto from the engine, which will loose the set timing when the drive gear or auto unit comes off the tapered armature shaft, and then dismantle on the bench.

 There is plenty of information about stripping and checking the magneto, and ways of releasing the drive gear from the armature. Plus a few thing to watch, all in the literature section of the Forum. Also Priory Magnetos and Brightspark Magnetos are highly recommended, with very useful of information on their respective websites.

Try the easy stuff first, fingers crossed!

 For a weaker mixture the needle needs to be lowered, so use the top groove for the clip.

Swarfy.

Offline ALPH1

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Re: A10 Running Lumpy
« Reply #5 on: 03.10. 2019 17:19 »
Thanks Clive, Swarfy.

Yes they symptoms do seem to suggest an overly rich mix and I'll hopefully see an improvement when I install the carb repair kit including jets. Yes I'll have to get to the bottom of the carbon rod including spring and where they went.  Im not 100% convinced they are in the mag but its missing and my thoughts are it could be.

Swarft,

Thanks for the advise. I did read resetting the auto timing required you to measure back from TDC a % and I have a gauge but found it to be almost useless for measuring the right distance. I'll definitely start with the easy stuff and see if I can locate the that rod before going at it on the bench.

Thanks

Al       

Offline Minto

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Re: A10 Running Lumpy
« Reply #6 on: 03.10. 2019 19:54 »
Hi Alph1
Now that is a weird coincidence, just a couple of days ago I did some investigation into my rough running issues, and found the carbon brush missing from my right side lead pick up, poked about in the mag from the top pick up hole and it immediately fell out. Put it back onto the spring which was still retained tightly in the pick up, reinserted in the mag and hay presto, misfire under heavy load sorted!
I had also dropped the throttle needle a notch which seems to be giving me a better idle, but this hadn’t sorted the misfire under load, hence the look into the mag.
Hopefully yours will be an easy sort.
52 A10 plunger

Online chaterlea25

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Re: A10 Running Lumpy
« Reply #7 on: 03.10. 2019 23:38 »
Hi Al,
A blast from an airline will remove any remains of the brush if it is still in there, a cloth under the lower pickup hole might catch it
I dont know where in Ireland you are ??
There is a Classic and vintage show at Leopardstown racecourse on Saturday,
I am heading up there and can organise a mag brush if you do not have a spare

John
1961 Super Rocket
1963 RGS (ongoing)

Offline ALPH1

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Re: A10 Running Lumpy
« Reply #8 on: 04.10. 2019 10:08 »
Hey John,

Thanks a lot for the generous offer. I ordered new leads and plugs from feked and they arrived the other day and the spark in now very strong. Yeah good advise.. I'll put and air line on it today. Are there bikes at the show tomorrow. Might take that in myself.

Word of advise for people like me.. dont put a finger and cloth in the mag while turning it over. SHOCKING IT WAS :)


Al
 

Online muskrat

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Re: A10 Running Lumpy
« Reply #9 on: 04.10. 2019 10:17 »
  *bright idea**lol* *lol* *lol*  *red*
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Offline Swarfcut

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Re: A10 Running Lumpy
« Reply #10 on: 04.10. 2019 11:43 »
That's why I suggested working something round the slip ring, rather than turning the magneto armature. Still, proves the thing works. Chaterlea John assumes you have an airline, if not try my trick, even a bit of duck tape on a stick to retrieve the bits.

 Fingers in slowly rotating magnetos is something we've all done...just the once. Next time take off the points plate before you dig deep. This will not upset the timing

Swarfy.

Offline ALPH1

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Re: A10 Running Lumpy
« Reply #11 on: 04.10. 2019 13:42 »
Cheers Swarfy.

Al

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Re: A10 Running Lumpy
« Reply #12 on: 04.10. 2019 14:21 »
Hi Al,
Yes bikes on show and autojumble
I'll send my mobile number to you by pm later
John
1961 Super Rocket
1963 RGS (ongoing)