Featured 1971 T100c Refresh

Iron, OK, I still haven't taken the ignition switch out of the circuit but was trying to trouble shoot in another way following some other advice.

I used a voltmeter to check the battery before anything was turned on: 12.21

After the ignition is turned on: 12.08

Obviously I haven't ridden the bike much lately and it is not on a trickle charger.

I was then going to find where the B-B Transistor box White Wire is connected to a bike White/Yellow wire, but they are pretty well covered and it looks like I will have to remove the gas tank to find this connection. So when I get a block of time where I can do this I will.

A couple of other things, however. I can get the bike to start, and now it never runs nicely, always rough and variable. A bit of smoke too. While it was running I disconnected the left spark plug wire and it kept running at about the same pace. So I reconnected the wire and again, while it was still running, I disconnected the right spark plug wire and it kept running, roughly of course, but similar to when I disconnected the left plug. Might this be diagnostic of anything specific? Thanks!

 

OK, on my way. thanks!

 

Electrical troubleshooting! I'm still having trouble troubleshooting my 1971, Triumph, T100C electrical issue. I checked the wiring of the Boyer-Brandsen MK IV and it looks to be properly appointed. As far as I can see it is getting juice. I made a YouTube video in case any members can take a look and help me a bit more with the diagnosis. Thanks if you'll take a look here:

 

It seems to be only firing intermittently on each cylinder. The roughness you hear is that. I can still get it to run on either cylinder, but I think the spark is intermittent to each side. It used to run fine, then one day it started cutting out after a ride. Then I could ride it again for a bit till it started cutting out a bit, and I couldn't get it to rev up. I thought it was fueling so rebuild the carb but the problem remains. So it must be something electrical. I can get it to start and run a bit like in the video, but eventually it will not run. ? ?

 

OK, how about this? I am wondering if this is a different electrical problem or a carb problem. See the attached video of the plugs sparking when kicking the engine over. They seem consistent and uniform. Also, the plugs are wet when removing after running, so could this be a fueling issue and how would I troubleshoot this? https://www.youtube.com/shorts/C3Ui9Z6fVgQ

 

I'm still trying to figure this out. So the bike starts easily, but still runs rough, like it is missing intermittently. When running I removed one the right spark plug wire and it kept running, but less firing. After connecting the right plug, I then removed the left, and it kept running, but just barely. So it would seem the left side is not running as smoothly as the right side. So could this be a left side coil or wiring issue that for some reason is not letting the left side spark as strongly as the right side? Thanks for advice!

 

SR, I have 2x6volt coils. If you will see my latest post it seems one side is running better than the other. So I am wondering if it could be that one side, the left, coil is a problem and may not be firing as it should? Is this a possibility that a coil can still work but just not up to par? I suppose the only way to diagnose is to try another coil? Thanks for any ideas.

 

OK, I did make sure the battery was charged, having it on a tender and checked the voltage before doing this at 12.6. If this is the case could it still be the battery? Thanks

 

ALSO - I tried switching coils. I ran the bike with the spark plugs wires switched to the other plugs - ran the same rough. Then I started and ran the bike on the right cylinder only, once with the left coil and once with the right coil. I did the same with the left cylinder. All four times it seemed to run the same, no missing just running on once cylinder. So I am wondering what this tells me . . . it seems that both coils are working OK? Also both spark plug wires seem to work ok, even on just one cylinder. So when I hook the plugs up normally, it is still running rough, so more than one cylinder is firing, just not evenly. Any advice?

 

Wow, OK. So the old battery tested OK for voltage, but still it was a new battery that fixed it? I will give this a try - because of this is the problem it is a lot easier fix than going thorough the who wiring bundle. Thanks.

 

OK, so I have a 67 Bonneville with 12 volt battery and hooked this battery to my T100C. The same issue persists so the battery must be ok.

 

OK, just now getting back to diagnose and fix this T100. So I went ahead and got new coils and plug and leads and installed them. Now, when trying to start, my ignition switch seems to be on the fritz! I'm not getting that red light coming on when turning the key on. Any thoughts on how to troubleshoot this? Thanks.

 

There is plenty of power at the battery and the coils, but no spark. Perhaps there is a way to bypass the ignition switch to see if it is the switch?