T500 that stops running when hot,

[yeadon_m]

If TZ is right then you would find that the issue occurs more quickly if you ride fast, and possibly not at all if you trickle long, as it would depend of rate of fuel use beating the air inflow to the fuel tank. Or, ride with the cap cracked open (if possible on that design). Cheers, Mike
Ps; I am no expert but it sounds v unlikely that both coils would die and recovery in synchrony for they are entirely separate parts.

[jabcb]

Normal coil primary resistance is ~ 4 ohms & resistance to ground is infinite.

If a coil has an intermittent primary-side short, so the resistance to ground is something like 2 ohms, then the coil will not fire the spark plug. The coil will draw a lot more current even when the points are open but not enough to blow the fuse.
On a T500, the additional current draw could drop the voltage supplying the other coil down to the point the other coil will not fire the spark plug.

So one bad coil on a T500 could cause both cylinders to have no spark.

[tricky1962]

This happened to mine. It stopped running as I was sat at a set of lights. I had a spark of sorts on both cylinders but could not get it to start. I bought two cheap, small 12V coils and with a little bit of rewiring had it up and running straight away.posting.php?mode=reply&f=2&t=8833#" onclick="window.open(this.href);return false;

If you wanted to test whether it was the coils or not, I suppose you could rig up a couple of car coils and see if that gets it running

[LexPaul]

I wanted to go ahead and finish this thread. My bike was down for 2 months while we figured this out. In the end, what happened was a stroke of luck. We took the stator cover off as soon as the bike stopped running and looked at the lamps while spinning the shaft with a wrench. that's when we noticed the the CDI Switch Box LEDS were not lighting up on every turn. Soooo, we thought the switch box was bad but then, while checking the lamps to see if they had any obstruction, we blew some air on them and the cool air cooled the lambs and they started working again. We were like, this can't be happening. So we kicked the motor on and ran it until it stopped again, no LEDS would light on the turns, blew some air on the lamps to cool them down and they immediately started working again.

Now the bad news. I contacted Newtronics with this information. Now remember, this is not the first time I called to ask them about what issues there CDI system might have and what I might look for in troubleshooting. Shayn at Newtronics told me almost immediately that they had had a bad batch of lambs go out and that they would send me a warranty pair. They sent the warranty pair and they were bad too. The factory took everything off the shelf and my bike sat, and sat, and sat idle. Anyway, I had to do move on and so I changed it back to points system and it's never run better.

The factory emailed me last week to tell me they are going to send me new lamps soon, if anyone wants to buy my kit, I am not going to go back to EI for now.

Also, I am about done with my T500 restoration. it is not a show bike but an awesome rider now. I have the motor completely rebuilt, new black cables (i do not like the way the gray cables get so dirty), new Michelin tires, rotors turned and wheels trued, carbs rebuilt, jemco chambers, and a complete (minus universal tool) tool kit under cover. The last things I am doing is new foam and seat cover and suzuki mirrors. Life is good with my T500 today.

Thanks to all of you for the help over the last two years..

[LexPaul]

I wanted to go ahead and finish this thread. My bike was down for 2 months while we figured this out. In the end, what happened was a stroke of luck. We took the stator cover off as soon as the bike stopped running and looked at the lamps while spinning the shaft with a wrench. that's when we noticed the the CDI Switch Box LEDS were not lighting up on every turn. Soooo, we thought the switch box was bad but then, while checking the lamps to see if they had any obstruction, we blew some air on them and the cool air cooled the lambs and they started working again. We were like, this can't be happening. So we kicked the motor on and ran it until it stopped again, no LEDS would light on the turns, blew some air on the lamps to cool them down and they immediately started working again.

Now the bad news. I contacted Newtronics with this information. Now remember, this is not the first time I called to ask them about what issues there CDI system might have and what I might look for in troubleshooting. Shayn at Newtronics told me almost immediately that they had had a bad batch of lambs go out and that they would send me a warranty pair. They sent the warranty pair and they were bad too. The factory took everything off the shelf and my bike sat, and sat, and sat idle. Anyway, I had to do move on and so I changed it back to points system and it's never run better.

The factory emailed me last week to tell me they are going to send me new lamps soon, if anyone wants to buy my kit, I am not going to go back to EI for now.

Also, I am about done with my T500 restoration. it is not a show bike but an awesome rider now. I have the motor completely rebuilt, new black cables (i do not like the way the gray cables get so dirty), new Michelin tires, rotors turned and wheels trued, carbs rebuilt, jemco chambers, and a complete (minus universal tool) tool kit under cover. The last things I am doing is new foam and seat cover and suzuki mirrors. Life is good with my T500 today.

Thanks to all of you for the help over the last two years..

[LexPaul]

Hope this updated photo comes across..

[GT750Battleship]

Sounds like it is running out of fuel. Next time it dies, open the fuel filler cap and see if that fixes the problem within a minute or so.

There is a pin hole in the filler cap that allows air to enter the tanks as fuel drains out. If that is blocked the tank creates a partial vacuum and fuel stops flowing.

+ 1 on TZ's assessment of what's going on...had this problem with my GT750 on more than one occasion,an easy, & more importantly cheap fix....!!
Cheers,
GT750Battleship.