Erratic running but not all the time

[Carter Turk]

I'd say it might be the ignitor. Mine gave up the ghost on the 83 Kat.
I would get intermittent function, and finally discovered doing a dyno run that the ignitor was breaking up at 7k rpm.
A Dyna-S might be an option and eliminates the ignitor all together.
I've had a few issues with the Dyna-S, having one trigger for 1-4 not functioning.
They took care of it, then I had the signal magnet come loose and scrape thru the pickups.
They took care of that as well.
A great company to work with when problems arise.
They can be had for under $200 and might eliminate fixing everything else electrical only to find it does the same thing again.

[alke46]

Right. It's back in limp mode as from leaving work today.
Worked fine all the way to work and is now not running from when I took off back home.

Same detail in the situation is that it has rained on the bike all day after I parked it.

Next move will definitely be changed the plug caps and wires.

Does anyone have a generic cap reference ? And also is it possible to change the wires on the coils or are they stuck on the coils ?

Thanks

Sounds like it's time for the ohm meter to check the plug wires at the very least. If the caps have not been replaced recently, that would be a 1st step to take. NGK is the brand you want.

[OldVet66]

The Bakelite caps become porous with age and will break down in the rain. When you replace them cut about 1/4" off the ends of the wire to get rid of corrosion and stick an ice pick or something similar down the center of the wire strands to spread them slightly so the caps screw down the middle of the wire evenly (If you have stock coils the wires are epoxied to the coils.)

[Katana 750]

Hi

Changed coils cables for new and put NGK caps.

Worked perfectly for a week, went out yesterday and came back home fine. Today upon going to work its not working properly again.

Kinda getting a bit bored by now

[OldVet66]

Maybe you lightened the load on the ignitor since you cleared any problems with coils wires or caps, but it may still be breaking down. Diagnosing problems on an old bike can be frustrating, especially intermittent ones, but definitely worth it when you fix the problem.

[Katana 750]

Hey

Yeah early 80s bikes are my only and daily rides, they're super when all is good but indeed I'm having trouble with this one.

What you call ignitor will be this :



I have a GSX1100E from 1980, the ignitor looks like the same one on the GSX750S ? If it is I could try it out on my faulty bike ?

Thanks

[OldVet66]

I could not find a GSX listing but the signal generator and ignitor for the GS models of those years were the same at parts outlaw. If your parts match you could use them for diagnostics. It's most likely a module on the timing plate breaking down if the bike continues to run somewhat when you are having trouble. That would cut you down to two cylinders but I suppose the ignitor could partially break down while it is failing.

[Carter Turk]

Hey

Yeah early 80s bikes are my only and daily rides, they're super when all is good but indeed I'm having trouble with this one.

What you call ignitor will be this :



I have a GSX1100E from 1980, the ignitor looks like the same one on the GSX750S ? If it is I could try it out on my faulty bike ?

Thanks

1100 probably would work, but it's just another 37 year old questionable GS component.
The Dyna-S eliminates the ignitor all together and the risk of using another used ignitor known to fail.
Might want to also check the conditon of the stator and regulator rectifier, but you did not mention having any battery draining issues or use of a trickle charger between strandings. If you do decide to get a Dyna-S, might be a good time to get their 3ohm green coils too.
All simply suggestions to ponder.