Horsley-Anarak wrote:My money is on a duff Villiers coil.
looks like you're the winner H/A.
coil is intermittent. seems that it decided to work the times when i externally connected a spare plug to check for spark (and i'd get a fat blue crackly one), but it would stop working when i'd tried to run the motor. there were a couple times when i would get a "pop" and i guess those times when the coil would work for a moment. at any rate it worked enough for me to look elsewhere, but from now on i'll move the coil up further on the "whats wrong" list.
thanks for all the help.
regardless of the trouble, its damn nice to see the motor run. its one that i got in a junk pile with two others. hopefully it'll run as good as it looks because the tubes, tiller and other grubby parts responded well to a good buffing with polishing compound and a cloth wheel and the cylinder and lowers got a fresh coat of paint. she looks like she did back in the day. it'll make a nice addition to the collection.
now i gotta find another coil to replace the one i used. anyone heard of rewinding these coils? i've wound power transformers and radio rf coils using the lathe. i hate to toss parts if they can be fixed with a reasonable effort.
40 Tpi is looking at rewinding villiers coils. Copper wire hair thin, insulation between layers. Loads of work, are they rewinding coils in the States ?
Horsley-Anarak wrote:
...are they rewinding coils in the States ?
H.A.
not sure if anyone over here is rewinding.
having access to a lathe or even a drill-press (anything with a chuck that can be slowed down) makes it easier. its amounts to making a simple device to keep tension on the wire as the frame turns, and a counter to keep track of the number of turns. i've wound coils (simpler than the villiers) by hand and its not fun at all.
I've repaired a few coils by unwinding until i found the break and soldering. in these cases i got lucky because the damage was just a few turns making it easy to re-wind by hand.
might try my luck with this defunct villiers coil this winter when i'm snowed in.
I have never had a coil that was intermitent, they go or they don't.
It's more likely to be a flakey plug lead, or a flakey plug, read the FAQs & renew them.
Try it on easystart spray, to see if you can get a burst of activity, if it runs on eaststart you have enough compression & a spark at the right time so it must be the fuel system!
Make it idiot proof and someone will make a better idiot.
the high voltage in the secondary winding can intermittently arc between windings if the wire insulation varnish is breaking down. the voltage in the secondary winding can jump the .020" plug gap, so there's certainly enough to jump the gap between windings where the insulation has degraded thus giving a weaker spark and you'll get no spark if the arc goes to the iron core (which is grounded). also problematic: currents in the primary winding are tiny and anything that could add resistance in this circuit can cause problems.
Charles uk wrote:
It's more likely to be a flakey plug lead, or a flakey plug, read the FAQs & renew them.
tried 3 plug leads - all with the same result. it wasn't until i replaced the coil that the motor ran for extended periods.
Charles uk wrote:
Try it on easystart spray, to see if you can get a burst of activity, if it runs on eaststart you have enough compression & a spark at the right time so it must be the fuel system!
tried that yesterday when i first started troubleshooting before i swapped carbs.
the problem was just as H/A predicted. if i had listened to him I wouldn't wasted nearly as much time.
found a shop here in maine that winds magneto coils. as i understand the internal configuration of the viliers coil is a bit of a mystery, but this shop says they disassemble one to determine its makeup.
they have a machine designed to wind the fine copper wire thats typical of these coils.
i'll chat with them to see if rebuilding these coils is practical.
Jerry In Maine wrote: as i understand the internal configuration of the viliers coil is a bit of a mystery, but this shop says they disassemble one to determine its makeup.
There is nothing complicated or a mystery on the internal configuration. It is a simple autotransformer. Check back over posts by H-A and myself for details and pics.
Jerry In Maine wrote: also problematic: currents in the primary winding are tiny and anything that could add resistance in this circuit can cause problems.
Currents in the primary are far from tiny! It is RPM dependant but around 5A pk ( measured with a fast Tektronix Hall effect current sensor) is not uncommon at a few thousand RPM in a Villiers Mk1 M1634! It is quite correct however that the primary total connection resistance should be minimised wherever possible to maximise primary current. ( This may be the reason that BS introduced a locking grub screw in the pole cheek pieces on the MK1 magneto. The earlier Marston pole pieces are simply a push fit onto the coil core! And at this point in history those holes have pretty rusted walls; but it is an awful lot of work to strip and clean. The changeover to a full internally soldered points connection on the M1634 coil is a cost reduction as well as the elimination of internal contact resistance on the bolt /grub screws on the earlier Marston coil.
had no idea pri currents were anywhere near 5A...that explains the relatively thick guage wire I found in the primary windings when I opened one up. makes sense though now that i think more about it...those currents are what cause the breaker points to arc if the condenser is bad or not connected.
