[exavid]

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Graham B wrote:

Thestory so farin this sorry tale.

The problem is that when hot, the starter motor won't turn the engine. It tries but just hasn't got the umph! So (and some of this was for other reasons) I've;

Graham, try to crank the hot engine with the kill switch off. If this doesn't make a difference it's most likely the problem lies with the starter, as per Twisty's info. If it does then there's the possibility of some kind of pre-ignition with the engine firing too soon or being too advanced when hot for some reason.

I had a Chevy back in the days when the starter button was separate from the ignition switch and could start it by cranking up and turning the ignition on after the engine was cranking. Turned out to be a bit of crud on the rubbing block in the distributor.

 

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Graham,

I see two possibilities, one would be a pretty carboned up combustion chamber, or early ignition timing when hot. A long shot could bea heat range on the plugs that's too high. How long does it have to sit before it will start up normally? If it's hot plugs or carbon holding heat, a rather short time should allow cooling to the point it would start normally, 15 minutes or so.If the bike had a mechanical advance it's most likely it was sticking in the advanced position when hot. I don't know the ignition setup on the 1100, I assume it's similar to the 1200 in which case the problem is likely to be electronic, pulse generator coils, or one of the sensors.Unfortunately the only 1200 I've worked on was an SEI and it has fuel injection and a whole different system.

There's plenty of guys here that know the 1100 ignition system, let's hear from some of you about how the 1100 ignition advance system works.

 

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Graham B wrote:

Exavid,

I have to admit I've not timed how long before things work again but I'd guess around half an hour.

Need to check the advance/retard unit but not too keen on taking the engine out (again) to do it umpkin:

The fact that the kill switch helps it start could also mean that the starter is getting more voltage with the ignition out of play. The more I think about it, I'm beginning to suspect the starter or the starter relay. It doesn't take more than a small increase in resistance to drop the voltage to the starter. Why only when the engine is hot? Possibly have a little more compression then. Twisty's recommendation on starter modification could well be the ticket. When you said you replaced the starter, do you have the old one you could put back in?

Just as an experiment you might try running on higher octane gas and see it it helps at all before you tear things down. Also try riding it for awhile using the kill switch start and see if it clears up any by itself. It's just possible the starter brushes do need to settle in a bit. If they had flat ends it will take a bit of time for them to shape to the commutator for maximum current flow

 

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Graham, take along a jumper cable and jump the starter directly from the battery when it's hot. That should prove out the starter relay and the intermediate wiring.

 

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Not a manual advance, I think you're referring to the vacuum advance not dropping back, stuck in the advanced position. That sure would do it.

 

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The only mechanical advance I know of on the GL1100 is at the rear of the engine. There is the vacuum advance and underneath it there is the centrifugal advance.

You can see the diaphragm housing on the top rear right of the back cover plate. There are three screws that hold the cover on the advance. An application of a bit of vacuum on the vacuum diaphragm with the cover off will show if the vacuum diaphragm can move the pickup coil mounting plate. With no vacuum it should be in it's most counterclockwise position. With some applied vacuum it should move clockwise. On the bike I'm currently working on the backing plate was stuck and required some exercising and a bit of lube free things up.

If you remove the vacuum advance housing you'll find the centrifugal advance. If that's sticking it will keep the spark too advanced and make the starting hard.

One thing I noticed when in there is that the right hand pulser coil is pretty close to the wall of the housing and the coil wire was rubbing on the wall. It turned out that the wire had slipped out of the little clip just below the coil and the slack was allowing the wire to touch the wall. Pulling the wire down carefully, inserting it back into the clip and judiciously squeezing the clip a bit got the necessary clearance to prevent wearing the insulation through.