Hi all

I'm after some advice regarding my m20 magneto, hope someone can help.

My M20 came to a spluttering stop whilst out enjoying the recent good weather, it felt like an electrical miss at first backfiring then power returning a few times before completely coming to a halt and not restarting. Firstly I removed the plug and kicked the engine over and no spark at all. Tried other plugs and no spark. Also changed HT lead and mag pickup, checked points etc with no joy.

I got the bike recovered and set about removing the magneto the following day. Just before starting, I thought I would give it a kick and it sparked once and then refused to spark after that. I continued to remove the magneto in the hope of finding something simple but no luck.

So here's where I need the advice.....I fashioned a drill and socket and used it to rotate the magneto and I get no spark at low speed but a very good spark if I speed the drill up. Its as though kick starting the bike does not achieve enough speed to generate a spark for starting.

Any thoughts on what may be the cause of no spark at low rpm?

Kind regards


Steve

Sounds like a condenser problem. Hot motor no spark! While you have the magneto off the bike try turning it with your drill in low light. Does it spark at the points? If so then condenser is probably duff. If so, a proper ovehaul is in order and will make life much easier and is well worth the price when you are next in the middle of nowhere in summer in full riding gear trying to kick the sod into life
Pete

did you also check the earth brush? (under the flat head screw to the left of the points cover)

Rick

Thanks for the replies so far, I have checked the earth brush and although it's got some wear I would say it's ok, also I checked for sparking at the points whilst rotating with a drill found that sparking does occur.

Thanks

Steve

Thanks for the replies so far, I have checked the earth brush and although it's got some wear I would say it's ok, also I checked for sparking at the points whilst rotating with a drill found that sparking does occur.

Thanks

Steve[/quote]
How would I check for continuity to make sure the earth brush is grounding?

email (option): ldj1002@yahoo.com

I've had my magneto armature rewound and condenser replaced (Paul Wolf, Bristol, ebay Rewound Armature For MO1 Magdyno #221440083223).

It was worth every penny (£120), but it does mean dismantling and re-assembling the magneto yourself. Getting the bearings off was a pain and he'll do that too if you want.

Maybe you can get it cheaper elsewhere but I can't fault his service.

Rick

email (option): rick.howell@talktalk.net