Mark Ohio 1976

Here is a recent picture. Sent from my iPhone using Tapatalk

I thought it would be a good to provide an update on my bike. I continued having ignition issues with the headlight on. Almost 4 years after my original post I think I know the root cause. A little background: a partially sheared flywheel key and leaking main seals and main bearings contributed to poor running of the bike but did not fix the bike. The bike finally died with no spark, so I troubleshot the issue down to the magneto. I replaced the condenser and points and the bike has spark again! Headlight on or off it runs great! I think the condenser had an internal short. I also have very little arcing on points compared to before. I never gave up hope that I would fix this bike, even though it took so long. It's been a great experience to learn so much about the CT2. Have a great day! -Mark Sent from my iPhone using Tapatalk

So I finally decided to expose the wires from just above the air box that runs back to the rear fender. I was reading higher resistance on the black ground wire, so I replaced it. I don't think that was the issue. I also found that the red wire going to the diode was not connected to anything(. The battery would not be connected to take a charge). I had put a newer blade style fuse on the battery positive wire, but I did not know the original fuse was in the back protective boot. After a test drive I found it to work! I added an additional ground from the battery ground point to the ignition ground point. Any ideas why the night charge not being connected would cause such an issue? I have 3 coils in the magneto, all three have been replaced. I guess the good thing is that I have gone over all of my wiring now!

Thanks for the encouragement! No, I connected it directly to the headlight coil, bypassing the ignition switch. How is the engine grounded to the frame? I am wondering if grounds are an issue. Maybe the lighting coil is finding ground through the ignition coil and back to the frame... My other theory is that the spark is weak and it gets weakened even more when I pull current from the lighting coil. Wires are new from ignition coil to plug coil... The spark would not jump the gap on my HEI spark tester. That may require more spark than this bike was designed with. Thanks for all the help!

I replaced the source coil. No help.... Could it be the other coil? I am running out of ideas! Mark

Ok. I picked up a manual. It says 0.5 ohms for the source coil. The coil reads 2.8 ohms (removed from engine). I ordered a new one. Do I need a dial gauge to set the points or can I set it to the alignment tab?

The source coil measures 2.3 ohms with points open. The ignition coil measures 2.2 ohms. When i measure from the plug wire to ground it reads nothing... Open? It has a nice blue spark when I kick it over, but it won't spark my HEI spark tester. So the wiring must be fine. It's either the source coil or the plug coil... What do you think?

I replaced the ground. Still running rough. The engine did not have a good ground, so I added one. Still running bad. The coil measured .8 omhs and the coil puts out 13 vac. If I put the headlight directly to the coil it runs rough... It's something down there.... Any ideas?

How do I inspect for tracking? The lighting coils are brand new. I soldered the ignition wire (new) to the new condenser. The only other wire goes to the points. What resistance will the coil(@magneto) have? Thanks for the responses. I am out of town, so I won't be able to troubleshoot until this weekend.

I disconnected the ground from the ignition switch to see if it is picking up a ground from it, but it still ran rough with the lights on. I inspected the ignition coil but did not find any issues.

I forgot to mention that I replaces the points and condenser. It seems like I might have a short in the night wiring (blue).... Not sure how it is affecting the coil source wiring though (black)

Hello everyone. I have a 1972 Yamaha CT2 175. Glad to find this forum! Mark

I have my CT2 running well, except when the headlight is turned on. The light works fine but the engine runs rough like the ignition is being grounded out. I checked the wire from the ignition switch that grounds out the coil when you turn it off, and it was open. It has a new lighting coil. When it roughs bad and I turn the headlight off it starts to run fine.