Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties Pa's 42WLA Build

Pa's 42WLA Build

Post Thu Sep 07, 2017 12:31 pm
Pa Site Admin

Posts: 6034
Location: Ohio USA

Steve...My other digital meter did go kaput. I get no zero reading with the prongs touching each other and the dial on it is loosing contact with its base. It won't even measure continuity. I put a new battery in it and the new battery made no difference. I checked for continuity using the small Electro Tech meter and it does not read a short from the coil body to the + terminal on the coil. Thanks again for the help in using the new meter.

Post Sun Sep 10, 2017 9:38 am
Pa Site Admin

Posts: 6034
Location: Ohio USA

Steve...I got 1.2 with the dial on the 200 ohms setting on the primary side. On the 20K dial setting I got nothing on the secondary side with probes in the two sparkplug wire suppression terminals. I would really hate to warm the coil to remove both wires again. But...If I must, I will. I still don't understand if my coil is bad, why do I get a good hot spark ?

Post Tue Sep 12, 2017 8:52 am

Posts: 319
Location: Ohio
Sorry it took so long to get back here. Paul at this point I don’t think removing the plug wires from the coil is worth the effort. I’m in the same boat as you when it comes to testing these things. I’ve taken readings from four coils I’ve got laying around and I’m still no closer to understanding what any of the readings mean except that no two coils read the same numbers. The only thing consistent between them all is that it is difficult to get any steady readings on the meter, if any at all.

I bought a new Taiwan coil at the beginning of summer and before installing it I tested it between the plug holes and had no problem getting a constant reading with the meter. I thought I was home free. The bike ran great for about a hundred miles. Now it will start on the second kick and idle fine but by the time I ride the bike a few miles it just begins to die. When it dies, it will not restart. If I wait 10 or 15 minutes it will restart but will not have enough power to ride it and after a few more minutes the engine will die again. Walk it home and the next day it starts easily and has plenty of power again until it warms up then it dies. I’m assuming that when the coil gets hot that it is failing, if that is even possible, I don’t know.

Anyway, I can tell you this. The time I had your problem of not starting and fuel drooling out of the carb while kicking it over I tore the carb apart again and couldn’t find any problem so I replaced the coil and bingo everything was fine again for a while. Like I said, I’m as lost as you are as to what the definitive answer to our problem is. I guess if I where you right now I’d rather pull the carb and check it for peace of mind before messing with pulling those wires out of the coil.

Post Tue Sep 12, 2017 11:36 am
Pa Site Admin

Posts: 6034
Location: Ohio USA

Thanks Steve. I am going t pull the carb off and go through it once more. Maybe something is blocking the idle speed passage. The gas only runs out the carb when I choke it. Nothing runs out when I do not choke it. I think I will pull the plugs and lo at them as well. I can test them individually for spark with them out. My spark tester shows hot spark but maybe the plugs are dirtied up with soot. What really bothers me is the engine ran great until the nos cork float swelled up and I replaced it with the modern float. I know the modern float is working properly because it shuts of the fuel when it should.

Post Tue Sep 12, 2017 4:26 pm

Posts: 3296
Location: Central Illinois, USA
While you have the carb off, Pa,...

Please watch to see if the petcock seeps at all, even very slowly.
It can be quite a confusion if the bowl has over-filled while sitting.
(The floatvalve only controls fuel while the machine is running.)

....Cotten

Post Tue Sep 12, 2017 6:37 pm
Pa Site Admin

Posts: 6034
Location: Ohio USA

Will do Cotten.

Post Tue Sep 12, 2017 6:41 pm
Pa Site Admin

Posts: 6034
Location: Ohio USA

I just got to be thinking Steve. With an original oem wla coil, the plug wires go into the coil at different depths. One goes in fairly shallow and one goes in almost to the bottom. My probes would never reach the deeper one and even if I was able to improvise an adapter to permit reach, making contact with the needle sharp points in both ports where the sparkplug cables are pierced for connection will be almost impossible.

Post Sun Sep 17, 2017 10:48 am
Pa Site Admin

Posts: 6034
Location: Ohio USA

I managed to get back to my WLA starting issue again. I figured before I would remove my M88 again, I would do one more front and rear cylinder spark test again using my trusty old spark tester. Below are two video clips of this spark test. Sorry for the video quality but you can plainly see the good sparks on both cylinders. The spark has to jump the gap to the sidewalls by ¼” or better.

Rear Cylinder Spark Test:

https://youtu.be/wq6fB0qJmOo

Front Cylinder Spark Test:

https://youtu.be/ISOAd35jFjU

Then I decided to test my actual sparkplugs again. I got a huge surprise when I pulled them both. Note the amount of soot on them in the pic below. The logical guess is they started sooting up when my M88 began flooding out. That has to be the reason since the engine ran perfect prior to flooding out and there was not any black exhaust smoke even though I had the M88 idle speed needle dialed in at one click rich.

Image

I said to myself. You may have found the issue now. The sparkplugs are fouled and are not sparking. To verify this guess, I then tested both the front and rear sparkplugs for spark. I used the same plug wire to do this since I already knew both sparkplug cable leads were working in good order. See the sparkplug test videos below. As you will see, both sooted up sparkplugs are still firing. Sorry again for the poor video quality.

Front Sooty Sparkplug Spark Test:

https://youtu.be/nCSlf3Ba-GM

Rear Sooty Sparkplug Spark Test:

https://youtu.be/b_9qH90AYmY

The military service manuals say the proper way to clean the sparkplugs is by sand blasting. I cringe at sand blasting sparkplugs with fear of abrasives getting embedded into the sparkplugs and coming loose while in operation only to score the cylinders and pistons or even worse. How do you folks clean them ? Also… What modern sparkplugs do you folks use in your 45 engines like brand, part number, that equals early OEM Champion #3 heat ?

Post Sun Sep 17, 2017 11:30 am

Posts: 3296
Location: Central Illinois, USA
Pa!

Sand was all they had.
We enjoy glass beads.

Proper blasting (as explained to me by someone heavily schooled and certified to do municipal water supply tanks and the like), requires substantial pressure to cause the media to 'bounce' rather than embed.
Beads are supposed to 'hammer' off deposits, rather than cut them off.

No matter what, I would first disassemble any plugs that can be!

....Cotten

Post Sun Sep 17, 2017 1:04 pm

Posts: 374
Pa I think there is no use in cleaning them, the film clearly shows a spark. The gasoline does not need much to ignite. When the mixture will be right, eventually they should burn clean anyway.

with blasting them you only risk destroying them. Better leve em alone, and if you really feel like cleaning them just gently brush em with a steel brush.. The charcoal should come right off since the engien hasnt ran that much yet

Post Sun Sep 17, 2017 2:46 pm
Pa Site Admin

Posts: 6034
Location: Ohio USA

Thanks Cotton and Samsup. I will lightly brush them cleaner. What I have gained by this testing is fuel delivery is my real issue. So.....Off comes the carb again. :) So what brand and part number sparkplugs do you folks recommend in the modern versions of sparkplugs ?

Post Sun Sep 17, 2017 3:07 pm

Posts: 3296
Location: Central Illinois, USA
Pa!

Anything but the most modern NGK A-6s that show resistance on an ohmeter.

....Cotten
PS: I would suggest a stainless brush for cleaning.

Post Sun Sep 17, 2017 3:32 pm

Posts: 1189
Location: Ojo Caliente,NM,USA
Carbon burns out with a propane torch fairly quickly. Oxy Acetylene is way quicker but sometimes melts the ground strap.
Dusty

Post Sun Sep 17, 2017 3:34 pm

Posts: 374
Although I dislike Vtwin and their reputation.. The Beck aircooled plugs they sell have been working very good for me. Expensive yes, but they do look the part. Also if you screw one into a head, it sits same as an original plug, whereas all the modern type plugs I tried are longer and protrude more into the combustion chamber giving a wrong flamefront ( or at least thats the theory we have here). I do think this has something to do with the better performance of these aircooled plugs. But technically the flatheads should run on practically anything that provides spark

Post Sun Sep 17, 2017 4:03 pm

Posts: 3296
Location: Central Illinois, USA
Samsup wrote:
... But technically the flatheads should run on practically anything that provides spark


The modern A-6s will, but not for long!

(The NGK rep swore they weren't resistors, but it came to light that they were produced to accommodate modern Wisconsin motors with electronic ignitions.)

Good old ones look real. New ones look like golden flying saucers.

....Cotten

Post Sun Sep 17, 2017 6:29 pm
Pa Site Admin

Posts: 6034
Location: Ohio USA

There seems to be to many choices in sparkplugs out there. :(

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