Hi guys,
I'm jut back from a week's trip around Normandy, escorting a convoy of WW2 vehicles with my WM20 (in 30 Corps markings)...
The bike did well until the last day, when I think I killed her! :-(
Is there anyone on the forum here that is local to me (I'm near Falkirk) that knows more about the bikes than I do and would be in a position to help me do some urgent repairs?

email (option): fozzie001@hotmail.com

Hi Ian,
i don't live nearby, but have you any idea what's wrong with the bike ?

Hi Mick,
A few things went wrong on the trip... some got sorted while others didnt...

First of all the timing turned out to be 180 degrees out... Thankfully one of the more knowledgeable chaps sorted that for me :-)

Then on a trip out (over an hour on the motorway) the inlet valve siezed open and all compression was gone, with the bike spluttering to a halt... After being trailered back to base, it had cooled enough to actually kick over once more and she started up first go!

Next, she became more and more difficult to start up and this went on until I dare not shut down the motor in case we couldnt fire her up again... I brought the bike back to camp and shut her down - that was the last time she could be started... One of the "experts" suggested it was the condensor in the mag that had finally given up, hence no more spark being produced :-/

Bike returned to the UK on a trailer.

email (option): fozzie001@hotmail.com

I'm sure I saw you a couple of times in Normandy.

If your timing was 180* out, the bike couldn't have been running when you left these shores!
I never hesitate with magneto's I always get mine professionally overhauled. It's easy to take the magdyno off and when it comes back from the repairer you can then ask here about re-fitting it.....Or bring the bike to me.....I'm only in Poole......Just about as far away as you can get

Your valve sticking issue would worry me, and I'd want to remove the barrel to investigate. But it might be that if your timing was too retarded and the engine was overheating, especially on a long motorway flog.

If you don't feel like touching the engine yet, I would get the mag sorted and refitted with the timing absolutely spot on. Then take some gentle rides to see how she goes.

It's lovely when your bike starts 1st kick every time. Some of us spent a lot of time sitting in the sun with our engines ticking over whilst others sweated for 10-15 minutes over the kick starter.

Ron

email (option): ronpier@talk21.com

Are you sure it was the inlet valve that was stuck ?
Mostly its the exhaust valve thats stuck, caused by overheating, just like Ron says.
That can happen when your ignition timing is to "late." The valve is then surrounded by fire.
Maybe try to find a member of any british motorcycle club in your neighbourhood.

I believe it was the inlet valve because the carb was smoking when I finally stopped... Plus that's what the other guys there told me.

Not sure what to do with the mag... I dont know how much it would likely cost to repair, or where to send it to... Or, I could have a go at replacing the condensor myself, but where to get a correct replacement condensor from is another mystery, or I could replace the mag, but then again, I'm not too sure if it's a left or right rotation :-/ (I'm so annoyingly inexperienced on these machines guys, sorry :-/

As for running retarded on the motorway, well, that probably was the case, as when I tried to advance it, the bike made a strange noise and didnt seem too happy at that setting - again, I'm not experienced enough to know what "correct" should sound/feel like... I could really do with a buddy that I can learn from, but it seems I'm the only M20 rider in Scotland :-(

Once the timing was sorted by the chaps on camp, she started first kick every time, which was a first too! :-) It was those guys that said she was 180 out and were very surprised that I had managed to start the bike at all, let alone run it.

I was with the 30 Corps group, we had 3 bikes with us & we spent most of our time shephearding the convoy of 20 vehicles from place to place. We met LOTS of other guys with bikes rfom loads of different places... My bike was marked up with 30 Corps Boar on the left side of the tank and HQ Signals (red 40) on the right. :-)

email (option): fozzie001@hotmail.com

Getting a mag reconditioned is not too expensive.

However, check the easy stuff first i.e.
1) Timing
2) Points and plug gaps
3) Gap on the exhaust valve lifter
4) Fit a new spark plug
5) Check that the carb flange is nice and flat and fit a "bakelite" type gasket between the carb flange and the barrel (this will stop fuel boiling on long hot runs). Make sure the nuts are tight. Mine can rattle loose after long runs, thereby letting in too much air and making the bike run lean (side valves really seem to hate a lean mixture and run really hot)
6) My understanding is that all points rotate clockwise on M20s. However, you may have a slack wire advance mag (here the adv/ret lever enters the mag on the left) or a tight wire advance (where the adv/ret lever enters the mag on the right). If you have the former, then pushing the adv/ret lever away from the handlebars will advance the ignition whereas on the latter you advance the ignition by pulling the lever towards you. On flat land you shouldn't have to mess around with the lever, just leave it fully advanced once the bike is up and running. You only need to use it fully freighted and/or going up steep hills.

I have not had an intake valve stick or the guide burn out. The exhaust valve and guide get by far the most heat.

Hope this helps.

Ian I'm quite sure if your mag was 180* out IT WOULD NOT RUN! God bless those guys for helping you, but maybe they were still out a bit or you were running it with the lever too far retarded.

Your Mag runs anti-clock at the drive end (timing side) and you should be running a tight wire advance system. That is:- cable coming out from the rear of the mag near the battery. So when you are running, you pull the lever by the clutch fully towards you.

I doubt you could do a successful repair yourself as there are also winding's and magnets to deal with. If you do a google search for MAGNETO repairs you'll find there are several around the country.

My advice would be to swallow the pill! Pay the £150-£200 and have it done properly which will last the rest of your life, and get someone to help you set it up correctly.

Ron

email (option): ronpier@talk21.com

Thanks again guys for all your advice :-) It REALLY is appreciated :-)
The guys in France certainly knew their stuff and checked everything over... Maybe 180 was an exageration, but it was waaay out from what it should have been.
Ironically, I went to the bike today (first time since France) and just for a laugh, I kicked her over.... Started first kick and ran like a daisy! :-/ I'm told that when it's cold it will start easily, but when hot, it won't - condensor?
I've got no problem biting the bullet and getting the mag sorted, if that's what I need to do...
Is this a common fault?
The paperwork I have for the bike says the mag and dynamo were both reconditioned 31/5/2012 by Hawker Electrical in Bristol at a cost then of £490.... Surely the mag can't have died with such little work?

email (option): fozzie001@hotmail.com

Well if Sean Hawker did the mag just 4 years ago it should be fine. But who knows without putting it on test? Sean is no longer in business however. I'm quite willing to take the mag to my reliable trustworthy guy in the New Forest for checking and repair if needed. It certainly wouldn't be anything like £400 and he wouldn't try and sell you a rewind if it doesn't need it. That is of course if you are prepared to remove it and parcel it down to me or him. But a rewind would put you in a 6-8 week queue. Ron

email (option): ronpier@talk21.com

Thanks Ron, I'll have to wait for a couple of weeks before I can strip it due to shows... the bike can be "static" till the shows are done...
Is it likely the windings are ok and the condensor blown?

email (option): fozzie001@hotmail.com

It's quite possible that the condenser is playing up but it's not a straight forward job to replace it. The only true way is to put the mag on test running for an hour or so to see if there is a problem. I can't emphasise enough that your engine should be running with the correct amount of advance timing. Guessing it at the handlebar lever like some guys do is not good enough in my opinion.

My mag guy says he frequently receives mags from Scotland for overhaul. He doesn't specialise in any one type like some firms and restores mags from all periods for tractors, planes, bikes and cars......The shipping cost is the same to the south of England as it is to your next village. Ron

email (option): ronpier@talk21.com