hi folks!
My WM20 lost sprk and refused to start the other day. Managed to roll it down a hill and eventually started firing although I had to get up to about 25mph first. On getting home (just) deduced there was no spark. Checked HT leads, replaced plug and cap and still no spark. This is after being a 1 kick starter...
Figured it was the mag and being in Hawaii away from mag rebuilders, I ordered and installed a Thorspark unit. I have a few other mag-dyno bikes waiting to be restored and thought this would be an opportunity to see if they were any good...
So, I installed it, double checked everything and set the timing so it was sufficiently close to get it to start. A very nice spark but she still won't start. Because 95% of electrical problems seem to be due to the carb, I dismantled it and thoroughly cleaned it too. Amal 626 concentric. made sure pilot jet was open.
Any ideas?
email (option): cas.vanderwoude@gmail.com
The Thorspark unit will only replace the condense. If the insulation on the windings are failing then you will get a weak spark. Get an old plug open the gap to about 1/4" put on plug lead rest plug on engine and kick over, a good magneto will produce a spark in air to jump the gap.
Actually, no. the Thorspark unit replaces the points with an electro-magnetic pickup, sending spark through a coil to the spark plug. Power to generate the spark now comes from the battery instead of the mag. The mag is there only to house the pickup and to adjust timing. All this seems to work ok - I now have a good spark - but can not get the old wheezer to start. Only an occasional blow back through the carb intake.
email (option): cas.vanderwoude@gmail.com
Sorry about that got confused with the Brightspark system.
A tappet (or both) closed up and stopping a valve from seating fully? Or maybe the valve lifter out of adjustment and loss of compression that way? If you have a good spark at about the right time and some fuel/air mix entering the cylinder then it has to be something else? Ring failure and compression loss that way?
thanks RogS. Its a long shot but I did not think about having 2 things fail at the same time. I'll check.
Compression is poor but ok. The tappets and valves I'll look at tonight.
email (option): cas.vanderwoude@gmail.com
Personaly i think an original magneto is a good system.
If anything is wrong with it after so many years, maybe it's best to go trough the trouble of having it reconditioned. Then it will work well for the rest of your life and would even add value to your bike.
An update on the Thorspark conversion.
A bit of fiddling with timing and old Wheezer is a one-kick starter!. Easy to time with a strobe so now I have a reliable ignition system. I know the vast bulk of people strongly recommend rebuilding the mag, and I agree, a mag is a reliable system. However there seem to be some misconceptions and the reasons offered by the pro-mag folks are sometimes not logical (to me at least). At the risk of starting a war, I'd like to run through some of these in a logical way:
1. Switching to an ignition system powered by the battery is less reliable. If the dyno or the battery fails, you will be stuck at the side of the road with no way to fix the problem.
True - but if the mag fails (which it will one day) you will also be stuck at the side of the road. If the dyno or the battery fails - you have an early warning system - the ammeter. When that sucker shows a negative balance between power generated and power consumed, you know failure is imminent. A coil system uses about 1/4 amp of power. A 9 amp hour battery should give you at least 4.5 amp-hours, enough for 18 hours of riding. If you have changed out to LED (which we all should), you still have at least 9 hours of riding with full lights. That is enough for most folks to get home.
2. A rebuilt mag is very reliable, just make sure the rebuilder has a good reputation.
True. But a rebuilt dyno is also very reliable. It is easier to pull off the bike and much cheaper to rebuild. Even when running poorly, it only needs to generate a 1 amp charge to keep the battery topped-up.
3. A mag avoids issues with the notoriously weak electrical system on Brit bikes. Even if this fails, you can still get home on a mag.
true - But we know how to fix this don't we? electronic regulators, new wiring, modern fairly reliable batteries, LED lighting systems which reduce power consumption by 90%?
So now lets look at some advantages of an electronic system powering a coil:
1. It's much cheaper than a mag rebuild, about 1/3 the cost.
2. you can set timing with a strobe - accurate, precise and easy
3. in theory, you never have to adjust the timing again, EVER
4. between services, the timing and points gap slowly go out of adjustment which means for most of the miles we ride, they are not optimal. not so with an electronic system.
5. Even with a failed dyno, a quick charge (or battery replacement) and you are on your way.
At the very best (or worst) it's a dead heat. So, the choice between the two options is just that - a choice, personal preference whatever. There is no real advantage either way. And, as long as we stick to the oath "do, no harm", everything is reversible. There is no impact on values (which I don't care about anyway). I ride old Wheezer to work every day, even if a few rivets are not correct, I just want a reliable ride. OK - I'm gonna put on my aluminum foil hat, grab a bourbon and wait for Armageddon.
email (option): cas.vanderwoude@gmail.com
Hi cas,
Check that you have set the tlmlng on the compression stroke,
It's an easy mistake to make ..(DAMHIK)!!
email (option): Seamusmalone15@gmail.com
In every hobby I partake in, I tend to do things a little different. Fishing with cane rods and ancient tackle, shooting is a relaxed walked up day where we 'may' get a shot and biking I choose to rebuild an old war horse.
Point is, however I decide, it is to make me smile not others, so if it makes you smile to have a reliable ride to work and you can enjoy one of these bikes every day, you are doing it right, regardless of what ignition system you choose.
I tip my hat to you Cas, have a great time.
Darren 😎