41 el

[Ducbsa]

I time my Lucas mag using an LCR meter ($26 on Evilbay) , using the inductance setting. When the points open, the reading changes by an order of magnitude.

[rhysmort]

I had something I've never seen before and can't explain it. My front plug boot came off and was hanging near my clutch, the wires I used are copper coore cloth woven. The boot had a little circlip holder on it. Now, what was happeneding was the spark was arcing, through the rubber boot?!? through said clip and jumped to the clutch backing plate.

I've never 1) seen a spark arc through a rubber boot, 2) Understand how the fak it's doing it. All I can assume is the integrity of the wire I bought has broken down somehow, I've been chasing carb issues, when it looks like the 'spitting' I still have could well be due to the spark breaking and not always firing and then when it does it's got a shit load of unburnt fuel, flames out of the pipes, spitting carb.. confusing to how.

Going to buy some accel wires and boots and take it from there!

[richbob]

I had a mag HT lead shorting problem with those same wires as you
i had twisted wires together
I routed them so they were not touching and that solved the problem
i had no caps and had a soldered/crimped on ring connecter to spark plug.

[rhysmort]

Originally Posted by richbob

I had a mag HT lead shorting problem with those same wires as you
i had twisted wires together
I routed them so they were not touching and that solved the problem
i had no caps and had a soldered/crimped on ring connecter to spark plug.

Ah shit! Yeah mine are together, not twisted but close enough.

I'm going to go Taylor or Accel, expensive but at least I know they'll be good quality!

[dbkp]

You probably already know this, but you need solid metal core wires with a magneto. The old industry standard was Packard 440 wire for mags, pre suppression, and pre electronic ignition wire. Some of the older supply houses still have this in stock . Most solid core wires will work fine. Have you tried a new condenser, I had a similar problem on a 59 XLR and that was the culprit. Get a good quality name brand(USA made if possible) I went through 2 new cheepo's before I got one that did its job properly.

[rhysmort]

Originally Posted by dbkp

You probably already know this, but you need solid metal core wires with a magneto. The old industry standard was Packard 440 wire for mags, pre suppression, and pre electronic ignition wire. Some of the older supply houses still have this in stock . Most solid core wires will work fine. Have you tried a new condenser, I had a similar problem on a 59 XLR and that was the culprit. Get a good quality name brand(USA made if possible) I went through 2 new cheepo's before I got one that did its job properly.

Hey man!

Yeah, I've got proper solid copper core, but they're arcing through the boot. I've bought some new wires (Accel) and I have some new condensers on the way, was yours spitting the through the carb under low load due to the condenser? It certainly could play a part, but this mag came off a perfectly good running bike.

Not to say something hasn't gone bad. Will change both this week!

[dbkp]

my experience with Mags has been generally good. Wrong wires, CONDENSERS, and cheap points have been my main issues. Had one with weak magnets that worked fine above 40 degrees F, but was miserable below 40. Up til about 10 years ago, we had an industrial/farm parts supply house here that rebuilt mags and carried full parts for Fairbanks Morse. Those days are gone. One thing I learned was that a condenser can cause all sorts of problems and quite often the symptoms are not always the same. This can happens with point coil setup or magneto. The rebuild guy told me that sometimes they act up when cold, and sometimes when hot, and often enough a new one will not work right. He said that a simplistic description of what it does is it collects excess electricity that would otherwise bang around causing trouble(sound familiar?) and condenses it to a steady flow. Since mags are alternating current the points (good ones anyway)last about forever. Most of my K's and XL's started just fine (usually 1st to 3rd kick after prime) with a properly dialed in mag, AND a carb with a float bowl and an accelerator pump. And yes, hard starting and spitting were some of the symptoms at one point. Don't know if this helps much, but that's my experience.

[dbkp]

Got another Question, Are you using the big stock style 18mm plugs, or modern plugs with adaptors? This can cause problems.

[rhysmort]

Originally Posted by dbkp

Got another Question, Are you using the big stock style 18mm plugs, or modern plugs with adaptors? This can cause problems.

18mm plugs. As for your previous regarding the mag, I know this one I'm using is tip top. It came off my running UL,I went through it before christmas and it's like new. It's not mag related, I mean, condenser could be playing up. I'm going to change that. BUT, if the spark is arcing through the rubber boot, there's a break down in the wire I've got. I bought a length of it and have used said length for both wires. It could definitely be a point/area of contention.

I've never known 18mm plugs cause an issue with it? what's your experience with them?

[Ducbsa]

I get the solid wire plug leads for my Lucas mag from Tractor Supply. Other farm stores should have the solid leads, too.

[magnum45pete]

you can get copper core plug lead wire at any Motorcycle accessory or car parts store in England near enough, & it's cheap as chips as we say, it isn't hard to find, certainly no reason to spend shit loads in getting it from the States,...remember to check if you have to use 7mm or if you can fit 8mm, early caps were for 7 mm only .... chuck the trendy cloth covered wires away, it's all cheap shit that fails but priced high for the looks NOT the performance. Get some modern made wire core leads and Non Suppressed caps as well,.... some things are worth doing properly where a running motor well is concerned.

[rhysmort]

Originally Posted by magnum45pete

you can get copper core plug lead wire at any Motorcycle accessory or car parts store in England near enough, & it's cheap as chips as we say, it isn't hard to find, certainly no reason to spend shit loads in getting it from the States,...remember to check if you have to use 7mm or if you can fit 8mm, early caps were for 7 mm only .... chuck the trendy cloth covered wires away, it's all cheap shit that fails but priced high for the looks NOT the performance. Get some modern made wire core leads and Non Suppressed caps as well,.... some things are worth doing properly where a running motor well is concerned.

Exactly what I've done Pete, I've bought some Accel wire which is exactly that. 8mm high quality. I've used the same cloth stuff before but obviously not this time. I've eliminated everything else upto wires/boots/coil.

Totally agree, I have an expensive 80 year old rare engine, why skimp on wires when everything else is so expensive?

[dbkp]

18mm are fine, Using adaptors for newer style plugs can cause some problems, but not what you are experiencing

[magnum45pete]

I use these ''DURITE'' end fittings on the Magneto end of the leads, they are available in 8mm. depending on what the cap takes, as i said early caps took 7mm & later ones were for up to 8mm leads.....lucas make the 7mm ones under the heading of ''lucas ht lead terminal fittings'' & look for DURITE for the larger size. they screw in and give a real good connection that will never let you down....they are on ebay but i'm not allowed to post a link for some reason, JJ seems to have something against someone helping someone out with links, i never understood that one for sure....

[rhysmort]

Gents,

I'm here as I have failed, I cannot find with any avail what the issue is with my knuck. It to me sounds electrical but hoping somebody can help.

I've tested the manifold and nipples, put 18psi through they are all sealed there's no leaks

After fixing the bushings in my carb the carb is now in great shape, I've also tried an M74 off a running bike which I know is dialled and works, the same outcome

I've got new plugs, I bought better leads, I've tried 3 different caps on my mag, one which came off my running UL I know it's in good shape. I've tried two different coils which I know both are working as intended and well. I'm literally at my wits end. I can't find the issue.

See video ;

You Tube

You Tube

Any ideas, thoughts on the matter would be a great help.

Rhys

[joe49]

What brand condenser in it? I didn't see that you have changed it. Are your points burning?
https://www.jockeyjournal.com/forum/...d.php?t=106961

Better leads? Solid core right?

Have you tried a timing light? Have you verified the timing mark?

[rhysmort]

Originally Posted by joe49

What brand condenser in it? I didn't see that you have changed it. Are your points burning?
https://www.jockeyjournal.com/forum/...d.php?t=106961

Better leads? Solid core right?

Have you tried a timing light? Have you verified the timing mark?

Bought two american made condensers, I forget the brand, changed the condenser, used my buzzer for timing, compression stroke front cylinder (always feel for air pushing out) timing line in middle of window), lock mag down fully advanced. My point have a little wear, but minor from use.

[Stormin]

An oscilloscope would be nice right about now that could tell you a lot, especially with all the things you have checked.

[750Devo]

Have you confirmed that your valves are sealing up? Maybe fuel mixture is being pulled in at the wrong time and getting kicked out with the exhaust. Would explain the flames.

[rhysmort]

Originally Posted by joe49

What brand condenser in it? I didn't see that you have changed it. Are your points burning?
https://www.jockeyjournal.com/forum/...d.php?t=106961

Better leads? Solid core right?

Have you tried a timing light? Have you verified the timing mark?

Originally Posted by 750Devo

Have you confirmed that your valves are sealing up? Maybe fuel mixture is being pulled in at the wrong time and getting kicked out with the exhaust. Would explain the flames.

Hey man,

Yeah I've put 20+ psi through the valves and they held at that pressure no problem.