Author Topic: magneto,etc. not firing on right side  (Read 3926 times)

Offline pedrochapala

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magneto,etc. not firing on right side
« on: 24.04. 2012 23:38 »
here's what i've done. new spark plugs,metal high tension leads,ngk spark plug resister cover, magneto posts. all both sides. only left side firing. tried 4 different posts including wrong side and still won't fire.
HEEEELLLLP!!!!!!
i am going to take off both posts and blow some air in, and then swab with q-tip and alcohol tomorrow.
i would think that if it's the magneto,both sides would be !$%#%&?

GRACIAS/THANKS!

Offline fido

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Re: magneto,etc. not firing on right side
« Reply #1 on: 25.04. 2012 07:16 »
Could be a major problem with the points cam so the points are only opening on one side.

Offline muskrat

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Re: magneto,etc. not firing on right side
« Reply #2 on: 25.04. 2012 07:38 »
Non resister type plug caps, leads & plugs for use with magneto.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Online beezermacc

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Re: magneto,etc. not firing on right side
« Reply #3 on: 25.04. 2012 08:39 »
Is this a magneto that has been working OK in the past or what's its history? Make sure the points are opening a sensible amount (0.010 - 0.020 though normal running is about 0.012) on both sides. I would swap the leads, pickups and plugs over as complete sets to see if the problem switches to the other side. n.b Muskrat's post - you must use non resistor caps and non-resistor plugs. Remove the earth brush and clean it, I doubt this is the problem but its an easy job with the mag on the bike. Also, try it without the points cover which may be tracking out in certain conditions. In the meantime I would suggest no plug caps at all, just twist the wire onto the top of the plug. When testing for a spark I usually test the end of the HT lead against the barrel/head, this eliminates any problem with the plug or cap. If none of this works I would take the mag off, and look for issues around the slip ring, maybe lots of carbon dust caused by poor quality pickup brushes - this is a regular problem nowadays.
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Offline Beezageezauk

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Re: magneto,etc. not firing on right side
« Reply #4 on: 25.04. 2012 09:41 »
Before you take your magneto off there is another test you can do.

You know that it's only firing on the left side.
Remove the right hand pick up completely and try it again.  Same result?
Remove the left hand pick up and replace the right hand pick up.
See if it fires up on the right side with the left pickup removed.
If it does the problem is a contaminated slipring as Beezermacc mentioned at the end of his reply and will need to be replaced.

Beezageezauk.

Offline fido

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Re: magneto,etc. not firing on right side
« Reply #5 on: 25.04. 2012 11:37 »
I've just re-read the original post and realise that he says it's not firing but does not say if there's a spark! Might be worth checking valve clearances and compression. ;)

Offline pedrochapala

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Re: magneto,etc. not firing on right side
« Reply #6 on: 25.04. 2012 20:26 »
ok. more background. new pistons, rings,valve guides and valves. new magneto cover, cam and points set at 12. and new steel ring too. that whole end is new. timing is fine.
the ngk spark plug resistor covers are fine because the left side works-no problema. all new copper wire and ngk plugs.
the engine has 33 miles on it.
the right side exhaust valve was not in sync,so i reset it.
then i blew air through both openings in the magneto. then i used a mirror and cleaned with q-tip and alcohol. 1 kick start and rode it 3 miles. it still misfires slightly on right at idle or low rpm, but runs like a deer-no misfire at higher rpm. the engine is at what i call normal heat.it heats up quickly here. i don't even have a choke.
maybe i missed some dirt?
sometimes it's the simplest things i'm hoping eh!
edit: i forgot to mention. i took the plug out and although it was starting to get colour,it was also wet.

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Re: magneto,etc. not firing on right side
« Reply #7 on: 25.04. 2012 21:24 »
Take the stupid resistor caps off. You've been well advised on that, above.

And make sure the plugs have no resistors in them.

With a magneto, the spark on one cylinder is always weaker than that on the other.  Any problem with HT voltage will cause one cylinder to miss, before the other.

Offline muskrat

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Re: magneto,etc. not firing on right side
« Reply #8 on: 25.04. 2012 22:27 »
And never use a plug with R in the model # eg BR7ES.
Cheers
PS the only exception is if running boyer micro digital ignition.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Online RichardL

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Re: magneto,etc. not firing on right side
« Reply #9 on: 26.04. 2012 04:19 »
With a magneto, the spark on one cylinder is always weaker than that on the other.  Any problem with HT voltage will cause one cylinder to miss, before the other.

Why weaker? Because, brushes, plugs, wires etc. have diferenences? Because cam is not perfectly symetrical? Otherwise, are you suggesting that there is some aspect of the mag's armature or magnetic circuit design that is asymentrical? The difference being that aramture and magnetic circuit asymetry would be design related, while the others are chance or random occurances. It would be interesting (to me, at least) to know which you are referring to. 

Richard L.
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Online beezermacc

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Re: magneto,etc. not firing on right side
« Reply #10 on: 26.04. 2012 08:03 »
Sounds like the only problem you are having is a slight misfire at tickover on the RHS. You have new pistons etc. so it might be worth doing a compression test to see if the new piston on the RHS needs more time to bed in, might just be low compression. Make sure your plug gaps are no more than 0.020". Are the exhaust pipes new? If so, are they turning straw coloured or blue? Do you have any blue or black smoke from the exhaust? Definitely remove resistor caps and plugs, the caps have as much as 30,000 ohms resistance in them. When you cleaned the slip ring was it very dirty? If it was, it is possible the carbon pickups are poor quality and will contaminate you slip ring again in next to no time.
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Offline fido

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Re: magneto,etc. not firing on right side
« Reply #11 on: 26.04. 2012 11:37 »

...the right side exhaust valve was not in sync,so i reset it....


As all the valves are operated by a one piece camshaft I don't understand what you mean by "not in sync". What did you do to reset it?

Offline pedrochapala

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Re: magneto,etc. not firing on right side
« Reply #12 on: 26.04. 2012 13:54 »
i think the dirt is my main problem now as i may not have got it all. so at it again today with carb cleaner and a modified toothbrush and air. i,m going to check the valves again. what i mean by in sync, is that both valves on rhs are closed at same time at 10 thousands.a pro advised that forget the manuals when setting valves . for 50 years he has been doing it that way. pretending it's one cylinder,then doing the other. i started doing it that way and found it easier for my old brain.
when i went in the intake was at 10 and the exhaust was touching so may have been slightly open.
in any event it now starts on 1 kick so i'm doing something right. 2 people with about 90 years experience between them, say the spark plug covers are fine[5k] and that's confirmed by the lhs working perfectly. the plug i'm using is an ngk b8hs. my points are set at 12 and i'm going to increase that to 14.
yes at 33 miles the rings on both sides are not broken in so it needs some good highway runs but i don't want to chance it until i am happier with both sides even though i have a cell phone-jaja!

Online Topdad

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Re: magneto,etc. not firing on right side
« Reply #13 on: 26.04. 2012 15:28 »
No disrespect intended about your friends but I'd take the advice given here regarding the plug resister caps ,when I had my mag rebuilt this was specified in the tech details sent back, even if it is okay now I'm sure  you're building up a problem for the not to distant future and any mag work is expensive,,these guys know what they are talking about best of luck BOBH
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Offline pedrochapala

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Re: magneto,etc. not firing on right side
« Reply #14 on: 26.04. 2012 16:03 »
no disrespect intended back atcha. check this product ngk spark plug resistor cover before making conclusions. my 2 friends also make their living repairing brit bikes only and obviously are successful at it with the years involved. we checked it out on an ohmmeter[?] before use. another friend but auto with 40 years experience. they won't damage my magneto. gracias