Intermittent ignition problems - side stand relay?

I'm running out of ideas!! I've got some sort of intermittent problem with the ignition on my Maxim. Sometimes it will start fine and go a few times. Then, for no obvious reason (to me) it will cut out whilst I'm getting my gloves on ready for a ride. Then it won't go, only turn over. The last time this happened it cut out when I put it in gear. The side-stand was up. This makes me think it's the dreaded side-stand relay problem so many of us have. Before I get the usual obvious answers: The entire wiring system has been checked for continuity and appears to be fine. I just had a new battery which I thought had cured the problem and it does turn over with plenty of energy. Please help!

 

... I just tried bypassing the side stand switch so it's not that either!

 

It's usually just the sidestand switch getting flaky.

However, if it is allowing the motor to turn over, it's not the safety circuit. If it thinks the stand is down with the bike in gear, it won't even let the motor crank.

I'd be more inclined to think your battery is becoming "marginal" or isn't being fully charged.

How many miles on it, and what Maxim? (they came in a few flavors.)

 

I've fixed it!! Thanks for your response bigfitz52, my bike is a 1983 XJ750K Maxim with only 15K on the clock.

I too thought it was the battery because even a slightly under par one can cause all kinds of problems. But this had a new one last week and was turning over well. Thanks to Chacal's very in depth description of the relays and switches and how to bypass them I've cracked it. It's worth explaining because it turns out it is the safety circuit and it still cranks. I tried bypassing the switch by joining the wires and grounding them. No good; still turned over but no spark. The side stand relay is under the left side cover by the TCI unit, not under the tank where the Haynes manual says it should be! I unplugged the relay and she fired up straight away! Just ordered a replacement one from the US.

 

Bigfitz52 - you said that the motor wouldn't turn over if it thought the side stand was down. Do you think that there could be a problem with the safety circuit given that the motor cranked in spite of the faulty relay?

 

My 1983 XJ750 Maxim still has an intermittent ignition problem. I'm looking back through previous messages to see if there are any clues in there. Removing the side stand relay worked. Now it won't go again.

I noticed that when the engine wasn't turning but the ignition key was on the tacho needle jumps around. That makes me think there's something wrong with the TCI unit.

Any ideas?????