Main fuse/Positive ground problems

Yep, fuel is definitely reaching the carb. Fuel is flowing through the right line no problem. I'm not sure much is coming out of the left line, but they are both connected before they get to the carb so that shouldn't matter. The issue seems to be in the carb itself. I guess I'd better pull it off and go through it again. I haven't messed with the needle and seat assembly that holds the baffle plate for the float chamber so far. I was assuming that affected things at higher rpms and wasn't the culprit here, but I'm not sure what else to do with the carb at this point. There is an air vent with a little pipe on it that I don't think I removed or blew out either. So there are still a couple of things I can do I guess.

I've cleaned the carb again, and I got it to run for a couple of seconds a couple of times this afternoon. It fired for a few seconds with the first kick, and its very cold out today (like 6 degrees Celsius), and I felt like I might have a shot at getting it to stay running if I could have kicked it over a couple more times while adjusting the air and throttle stop screws. However, I was getting some pretty serious kickback today, even if I barely moved the kick starter.

Would a battery reading of 12.26 v be low enough to cause kickback? Or is it more likely a loose or wet wire (it's raining). I'd like to avoid this hazard in future .

No if you have over 12volts you should be fine,it shouldn't kick back ,I think if it drops below 11volts a Boyer will go full advance and kick you back

You really do need good connections with electronic ignition and a good battery

Thanks Baz, yeah, it's quite possible I had a loose connection. I've got the battery charging now too. I'll check the wiring very closely before the next kick. My ankle requires a bit of a timeout .

Maybe take a look at Boyer's fitting instructions/ wiring and static timing just incase the timing has slipped,I doubt that it has but get yourself familiar with how the system works, what's the history of the bike? Who fitted the ignition? And the mikuni carb? Have you owned a British bike before?

The picture you posted showing the float chamber and the main jet covered with primordial soup would lead me to believe that the calibrated parts have seen better days. There I s an air passage that runs from the bell mouth, to the air trim screw (idle air) to a small passage just forward of the slide is very sensitive to dirt/crud.

Also, and it might be my eyes, but the float arm, un-loaded, appears to be bent down enough that the fuel level in the bowel would be too low. The float arm should be parallel to the float bowel seating surface when viewed with the carb upside-down. the tang that controls the float needle should be parallel without compressing the spring in the float needle.

The enrichener (called choke) is controlled by a rubber tipped plunger that is spring loaded to seal an orifice that allows manifold vacuum to draw fuel directly from the float bowel. The rubber doesn't last forever and can easily be leaking by, given the external appearance of the carb I'd say that it would be a good bet that your soaked plug(s) may have the enrichener to tank for their bathwater.

Others can give you a better explanation of this, but if your cylinders are being washed down with generous doses of raw fuel your rings won't seal very well, worse if they are in as good shape as the carburetor, but I can't say for sure.

Tie a "Q" tip to a long screw driver (securely) and drag it on the bottom of the tank; if your fishing expedition turns up the kind of crud that you photographed on the main jet, then start with a GOOD tank cleaning, or your carb efforts may turn into a do-loop

Overall the carb looks like it has seen about every kind of abuse a carburetor can be subjected to; you may want to start saving your money for a new one.

And, as others have mentioned, a 45 year old wiring harness and 45 year old ignition wires aren't doing you any favors. replacing the plug wires and rigging a stand alone firing circuit, with a kill switch would be an excellent way to get down to real basics.

The good news is that you have a real, all there, Norton Commando that seems like it wants to live. Good luck and best wishes.

Wow!!! Thanks for the detailed message RoadScholar, and for the encouragement . And thanks Baz for the quick responses on the full advance and kickback. And thanks again to everyone else who helped out earlier: L.A.B., Ashman, Torontonian, TexasSlick, MexicoMike, Rvich, Nortoniggy, Auldblue, Craig, Gortnipper, oONortonOo and Triumph2. You've all been wonderfully helpful, and this morning I finally made some serious progress.

Being the labor day weekend, I finally have some time to get at the bike properly. I took my time, made a list of things to go through, one at a time, in the correct order, to see if I could sort out the kickback and try getting her to run again. I pulled the plugs and gave the kick a few pushes and it was plain that they were sparking all out as soon as the thing moved at all. Because I'm working with a hotwire setup made with wiring ripped out of old vehicles at the local dump, and since my negative wire is spliced in a couple of places, I figured that was the likely source of the problem. And this turned out to be the case. One of the wire nuts I had used had come loose. I spent time making each connection as good as I could using the materials and tools I have at hand, and it paid off. When I was through she was sparking at the appropriate times again. To do this I removed the gas tank, and when I put it back on I check the plugs again to make double-sure that everything was working properly.

Next I went to the carb, which I had torn down, cleaned, and rebuilt the other day. I hadn't had a chance to really test it out since I was dealing with intense kickback that evening. I decided to test it out now that I had the ignition setup decently, and the only thing I did with the carb today was drain it from the bottom once, and I made sure that fuel was getting to it. After this was finished and all tightened up again I turned on the taps, pushed the enricher lever down and gave her a few kicks - the first few were very timid and ginger after the kickback session the other night, but before long it was clear that I wasn't going to get my leg torn off by the kick lever today. She fired for a second almost right away but that was it. I tried for a while and looked at the plugs and could see she was getting fuel this time. First time ever. And eventually I thought to try with the enricher lever up, since it's warm out, and for the first time with the lever in this position she fired for a second. This happened a couple of times and then I tried with a little bit of throttle and she fired up like a dream !!! This was the first time I was able to get her to run for more than 3-4 seconds maximum, and with a little tinkering with the throttle stop screw and the air screw I was able to get her to idle nicely. My neighbor came running over excitedly to try revving her a little and for a high-five, and a nearby construction worker came over to admire her and hear her run. I'm super happy at the moment. I may take her for a little spin after, but at this point I'm just overjoyed to have her running and to know that she works . When I'm done celebrating I'll get down to business on the original short circuit issue. I'll keep you posted, and will probably have lots more questions when I get into that.

Thanks a million again all for the help and the patience !!!! This forum is amazing.

Good on you Jamie !!! , nice feeling the first time she really comes to life ..... you realize now you prolly have the disease , good luck with that ... take your time making all your connections , worthwhile , now you know she/he
lives .... also you should give the brakes a good look over before you get too far down the road ....
Craig

Thanks Craig !!! I've been out for my first ride, and I'm definitely hooked now. She drives like a dream, and I'm happy to report that the brakes are working good, and all the gears work great as well. I've been smiling ever since .

So today I got down to business on trying to find the short. I've got the multimeter in action, and I've connected it up to my main leads and have a reading of 00.2 using the most sensitive ohm setting. Using the connectivity setting I'm getting a zero reading. I spent 2 or 3 hours going through the wiring harness, unwrapping etc. after disconnecting each component that I can get at. I've been able to disconnect the back light today too, and no change.

But a few minutes ago I took unplugged the zener diode (which I thought I'd done at least a couple of times before), and with that disconnected I'm getting a reading of 5.4 on the most sensitive ohm setting. Am I onto something here?

Thanks,

J

Actually folks, I think I am onto something! I went back out after checking the forum every 5 seconds for a half an hour or so, lol, and I tried putting the key in and turning it through each setting with the multimeter hooked up. It looks like I get a reading of 5.4 ohms when I've got it off with parks lights, but with it in the off setting, or either of the others I seem to be getting infinity. That's good right? Does this mean I've found the short and I can try connecting the battery properly and re-wrapping the wires etc??

Ok, assuming that I've found the short (see previous message), when I go to re-connect my white ignition wire, should I be connecting to a set of white and purple wires, or a set of black and white wires? I think it's the white and purple ones, but I want to be absolutely sure before I connect these ones. Thanks!!!

J

Supercat said:

when I go to re-connect my white ignition wire, should I be connecting to a set of white and purple wires, or a set of black and white wires? I think it's the white and purple ones, but I want to be absolutely sure before I connect these ones.

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As it has a Boyer ignition, and the "white" you mean is the Boyer box white wire (and not a 'switched' power supply, also white) then Boyer white should be connected to the (normally) white/yellow from the handlebar kill button (positive earth/ground) not white/purple or black/white.

http://www.boyerbransden.com/pdf/KIT00053.pdf

Thanks L.A.B. Hmmmm, I have a feeling this doesn't have a kill button connected. It looks like the left handlebar controls have been switched over to the right, and the others are gone. The white Boyer box wire was definitely connected to one of the two sets I mentioned before I unplugged it for the bipass. Pretty sure it was the white and purple ones. I think they must go to the main key switch?

Supercat said:

It looks like the left handlebar controls have been switched over to the right, and the others are gone. The white Boyer box wire was definitely connected to one of the two sets I mentioned before I unplugged it for the bipass. Pretty sure it was the white and purple ones. I think they must go to the main key switch?

Click to expand...

With a Boyer, the white/purple ('points' ignition *ballast to coils*) wiring should be completely disconnected, same for the white/blue (runs between kill button white/yellow and the ballast resistor which should also have been disconnected/removed).

If the kill button is not connected, then the Boyer white should be connected directly to the switched power white.

Black/white (and black/yellow) should only connect the Boyer pickup to the Boyer box, they should not be connected to anything else (see Boyer diagram).

*Although a 'white/purple' (WP) wire isn't marked on the wiring diagram it's the wire that would normally have connected the ballast resistor to both coil negative terminals with the original points ignition, and may also extend to the battery compartment although that section was never used.

Is there some way I can connect it to one set and/or the other and test things without trying to start it or connect the battery? Can I just leave the multimeter setup as I have it (to the main leads), and turn through the key switches? Would this be safe? It was definitely connected to one of these two sets before. And I'm 99% sure it was the white and purple set.

Also, I assume I can run this without the zener connected, if I just have the light on - is this correct?

Supercat said:

Is there some way I can connect it to one set and/or the other and test things without trying to start it or connect the battery?
Can I just leave the multimeter setup as I have it (to the main leads), and turn through the key switches? Would this be safe?

Click to expand...

Various alternative suggestions have already been given, such as, use a low wattage bulb in place of the fuse, or you could connect your meter set to amps (or milliamps ignition off) between the fuse terminals.

Supercat said:

It was definitely connected to one of these two sets before. And I'm 99% sure it was the white and purple set.

Click to expand...

I don't recommend you reconnect the Boyer white to any white/purple wire as the WP wiring is effectively redundant once the points ignition has been replaced with EI.

Supercat said:

Also, I assume I can run this without the zener connected, if I just have the light on - is this correct?

Click to expand...

Not wise, at least not for long periods and you'd probably have to limit the revs (to about 3000 RPM?) once the battery was fully charged. If the system voltage is allowed to exceed 16V for any length of time then the Boyer box can be damaged.

L.A.B. said:

Various alternative suggestions have already been given, such as, use a low wattage bulb in place of the fuse, or you could connect your meter set to amps (or milliamps ignition off) between the fuse terminals.

Click to expand...

This was for finding a short. My question was about connecting the white boyer wire to the wires it was previously connected to and seeing if I would get a different reading with the ignition switch in the on position, with no battery connected. It's possible the previous owner might have changed some of the wiring.

L.A.B. said:

I don't recommend you reconnect the Boyer white to any white/purple wire as the WP wiring is effectively redundant once the points ignition has been replaced with EI.

Click to expand...

Will it hurt it to connect the Boyer white and the white purple for the test described above? I'm not going to try it if there is any risk.

L.A.B. said:

Not wise, at least not for long periods and you'd probably have to limit the revs (to about 3000 RPM?) once the battery was fully charged. If the system voltage is allowed to exceed 16V for any length of time then the Boyer box can be damaged.

Click to expand...

Got it. Is there any fixing a zener diode, or do I just need to order one? Thanks L.A.B.

Supercat said:

L.A.B. said:

Various alternative suggestions have already been given, such as, use a low wattage bulb in place of the fuse, or you could connect your meter set to amps (or milliamps ignition off) between the fuse terminals.

Click to expand...

This was for finding a short. My question was about connecting the white boyer wire to the wires it was previously connected to and seeing if I would get a different reading with the ignition switch in the on position, with no battery connected.

Click to expand...

Supercat said:

Will it hurt it to connect the Boyer white and the white purple for the test described above? I'm not going to try it if there is any risk.

Click to expand...

I suppose you could -as a test.

Supercat said:

It's possible the previous owner might have changed some of the wiring.

Click to expand...

It's possible, so we can only go by your description of what's there when compared with the original wiring diagram but if it's at all possible to connect the Boyer white directly to the power supply white (so without the kill button) then there's no logical reason to include any other unnecessary extra wiring.

Supercat said:

L.A.B. said:

Not wise, at least not for long periods and you'd probably have to limit the revs (to about 3000 RPM?) once the battery was fully charged. If the system voltage is allowed to exceed 16V for any length of time then the Boyer box can be damaged.

Click to expand...

Got it. Is there any fixing a zener diode, or do I just need to order one?

Click to expand...

Yes, or, fit a modern regulator/rectifier (reg/rec box) such as Podtronics in place of the Zener and rectifier.

https://www.classicbritishspares.com/bl ... -rectifier

Wicked, thanks for the help, and for the link! The two in one Podtronics unit looks pretty great, and it looks like there are options that would allow for running with no battery with a Boyer setup. That's awesome.

I tried that test I described in the last message and there was no change to the readings with the Boyer wire connected to the white-purple. I'm not sure what this means, if anything.

But hold on one sec... here is step 19 from the Boyer instructions:

"19) Connect the white-blue wire (the one removed from the ballast resistor) to the white wire from the transistor box".

Are you sure I'm not meant to be connecting the white-purple wire that the PO appears to have used to the white Boyer box wire?

And one more question - if I am able to get spark using the actual wiring instead of the bipass, am I better off running it like that if I wanted to make short trips around town (like less than 5 km at a time), or would I be better of just using the bipass setup while waiting for the new part to arrive?

Thanks again!!