Took the '14 out today to join a local tour. (Ended up heading to the wrong location and never caught up with the tour)
Anyway, while driving home at 35 mph or so, the engine died suddenly. I switched from Mag to battery and it ran fine. I stopped for gas a while later and decided to try the mag again. It ran fine as I pulled into the gas station, and then ran fine on mag after restarting, but as I accelerated out of the gas station, it cut out at 25 or 30 mph. Switched back to battery and drove home.
Haven't looked at anything yet. I will pull the mag post and check for debris, & check the connections at the post and other end of wire.
Like you said- check the mag post. If its OK, and if you have a TW Timer, clean it thoroughly and often. Dust inside the timer is the weak point of the timer. And yes, from prior experience, the car will run on batt, but will not run on magneto if the timer is dirty. It did in my case and I don't know why.
Were you going uphill when it stopped? It is possible that the gap between the magnets and the coils is too great and either pushing in the clutch or going uphill would move the flywheel back away from the coils.
It could be a bad switch connection only on the magneto side of the switch. It is easier to find a problem when it is continuous than intermittent. Could be timer related. If it were related to the timer, I would think it might start misfiring on mag and run smoothly on battery, but to stop completely would be more like a loose wire between timer and switch or a bad switch connection. The reason I say this is because there are four segments on the timer and unlikely for all 4 to have a bad connection at the same time and yet still run smoothly on battery.
Had the same problem with my 27. Turned out the spring in mag post was bad
Poked around, not sure if I found the issue. This is what I found:
Coil box terminal for the magneto was a little loose. Not super loose, but I could rotate the wire end.
The number 1 plug wire was also loose and had dropped down such that it was very close to the battery post. They were so close, and the number one terminal was a loose so I could easily imagine they could touch with bumps while driving. Would touching the number 1 coil output to that terminal make the magneto cut out?
I pulled the mag post and didn't find any lint etc, but the lower part of the bakealite that extends into the hogs head was more or less missing. I I will get a new one. Are the show quality repos from Langs good quality, or should I look for a good original?
Mine either wouldn't start or would sometimes die then not start. I pulled the mag post repeatedly, swapped mag posts etc. then I figured out it was the switch because sometimes turning it on and off fixed it. I took it apart and cleaned it but kept it doing it so I shoved the mag wire in the switch direct. You could try something similar then you would know if your mag post or mag is bad or if it's in the wiring or switch. Be sure and disconnect the battery so it doesn't zap your mag.
Mine once stopped after hitting a bump in the road. After driving home on BATT, I unscrewed the mag post and found that the mag post contact had popped off of the button. It was dull so I sharpened the point so it would embed itself into the button. I have never had that happen again. I hope it is a simple fix. Keep us posted. Jim Patrick
You can test the magneto post contact without having to remove it if you have access to an ECCT with magneto test option.
The ECCT tests the magneto under load and no load conditions to calculate the internal resistance. The magneto voltage should be nearly the same regardless of load unless there is a magneto post contact issue or other defect.
More information available on the website www.modeltecct.com
I did some more digging tonight and took some pictures.
Pics of mag post - I don't think this was the issue, but the bakealite is cracked so I ordered a new one from Langs this morning.
This is inside the switch. Everything seemed to be making good contact.
This is inside the coil box. The coil box had a bit of very light carbon dust inside it. It would blow off easily, or wipe away if I brushed up against it. Could that have caused my mag issue? It was the first time I ever drove the car in the wet, but it was mostly damp and not actively raining much, I don't think the inside of the box could have been wet, but the air was moist. Could the carbon have been shorting things out when the voltage got high enough as the RPM increased? It ran fine on mag at low RPM... Seems implausible, but I don't see much else wrong.
I did find a couple of misplaced bits under the bottom coilbox wood. A brass nut that came from the switch mounting screw, and a little brass tab that I could not find the origin of. They didn't seem like they could have been shorting anything.
The solder joint on the bottom strip appears to have separated. There are likely carbon tracks in the wood plies; I'd say it's time for a plastic "wood" kit.
I also had issues with carbon tracks in the wood. I installed a Fun Projects plastic coil box, and wow, what a difference. It's like driving a new and totally different car