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Hmmm, this was on a '91 GS. Only other symptom was tach bouncing all over the place. Aren't the headlights separate from the ignition circuit? Note: electrics = not my strongest point. I still think it's crap in the jets FWIW.

Bamboo812 wrote:Hmmm, this was on a '91 GS. Only other symptom was tach bouncing all over the place. Aren't the headlights separate from the ignition circuit? Note: electrics = not my strongest point. I still think it's crap in the jets FWIW.

Correct Tim. Everything works, except starter, oil and alt lights and ignition.
What time is your electonics class? Can I make a booking for this afternoon?

For you and others. Never trust a glass fuse. They can look good and be bad. They can even be tested with a multi meter for resistance and show good, but be bad under the larger load of a circuit.

I prefer the ceramic ones with the fused material folded over the tips of the ceramic. If it is blown or corroded, it can easily be seen. They can grow green stuff, so clean off the holder too.

Never trust the fuse holders. The fixed type can lose continuity at the rivet. The plastic inline ones that unscrew can also have a bad connection, depending on type. The good ones are those that one can feed the wire into and through the holder to examine the solder connection.

I have found so many symptoms related to the above mentioned faults.

Duane Ausherman wrote:For you and others. Never trust a glass fuse....
I prefer the ceramic ones with the fused material folded over the tips of the ceramic.

Ceramic it is and always has been as they fit best in these bikes. Push them into position with the fuse material facing away, then turn them around so that they can be seen from the front. Pushing them in the other way can dislodge the folded fuse material at the ends if you're not careful and in that birds nest it's easy to do.

I'll get to go for a test ride this arvo if the rain stops. At 0130 this morning the heavens created a light and sound show you'd pay good money for and it's been flashing and thundering all night. It's been p, p, p, persistently precipitating ever since. My wife is asleep at one end of the house after a night shift and my daughter studying for VCE exams at the other end so no bike noise for a while!

Ignition switch inspected,cleaned and reinstalled. All lights work as expected.
Tank and taps flushed and cleaned.
New fuses.
New ICU.

The test ride saw it fail again @ 12.5 miles. It was running poorly, then when slowing it quit quickly. It did start straight back up again, unlike the first time the other day at a similar distance. It ran poorly and the tank cap was open until it stopped, so not a venting issue.

I pulled the plugs when I got home and they were black and sooty, whereas the other day they were whitish/grey. I then dropped both jet stacks, and they were mildly grungy. All cleaned and reinstalled. I'll check the air filter shortly, but that was fine a few weeks back.

It seems to idle well but is rough when revved. It was running well before all this.

I'm unsure what to test next, except to swap back the ICU. Maybe substitute the coil and/or the HT leads and/or plugs? Both plug caps felt equally hot.

Y'all may recall I had similar issues earlier in the year, but it never stopped, just ran poorly. The new coils seemed to fix that.

SteveD wrote:

daz wrote:Crackomatic coil?

Dyna brown. I'll substitute that out too.

Following the principle of easy things first, I put in a spare harley coil before tackling the ignition can. It started right up as it once did and the test ride had it running correctly, with good acceleration and no hint of missing or hesitation.
The coil fits under the main frame with the ht leads entering from the front. I used an angle grinder to form a space in the plastic bracket that's part of the mold of the coil so that it sits higher up off the air intake snorkels. The Dyna coil had the ht leads seated on the snorkels and bent to enter the coil, so I like this positioning better.
Happy now.

Have you still got an old beancan to try? is it an easy swap to check?

Fuel sounds less likely to be the culprit.

Edit: fuel issue, not HES. The bean can I have has a second lead on it Jeff. It's not very old. It's similar to the one sold by Motorrad Electrik but has the back up HES. I'd be pissed if that was it!

The only oem parts left of this ignition system are the switch itself and the connecting lead from the ICU to the bean can. I'm now suspicious of that lead. The can is less than 2 years old and the coils, icu, ht leads and ngk plug caps are only 6 months old.

What's most likely to heat up and not start until it cools down?

My next step is to substitute the leads, then coil, then the can. Easiest first and it won't take long.

#2 Edit: fuel issue, not HES. EDIT: I changed to the other available HES lead and it fired up and revved better. Annoyed by that as it's not that old! It's half buttoned up again so I'll finish that off and test ride it in the morning.

What's most likely to heat up and not start until it cools down?te]

My guess would be a Hall sensor or coil.
Just this last weekend I replaced a hall sensor in a bean can owned by my friend. The old one tested bad on the bench only when I applied a little heat to the sensor with a heat gun. It was an original Honeywell 2AV54.

Coils have been known to act up when hot since before I was born...may your coil STB