had a problem starting a 916 ST4 replaced sprag clutch starter relay and solenoid up graded wires from battery to solinoid solinoid to starter added an earth, new battery. bike will some times start first push of button other times its sound if the battery has not enough juice to start then kicks into life does any one have any ideas, when not in use the bike is on a trickle charge
Many things will cause this related to path between battery and starter as you are well aware I expect. It's often high resistance in the red starter lead, sometimes generally if old but most likely at a connection due to corrosion or joint becoming 'dry'. If you can, try and touch the starter terminal (pull back rubber boot) while cranking but be aware - it could get hot*. Ditto test for two solenoid connections and battery of course, Same applies for earths but they seem to play up less (but can't be ruled out). Like many on here, I have just routinely replaced my positive lead on a 900 Elefant (v. similar set-up/engine) because a terminal was overheating. If you are used to soldering you can get the leads and eyelets required to do both earth and live for around £12 depending on which gauge you choose (needs to be greater than standard). Damaged Starter solenoid internals can also produce symptoms you are experiencing - if careful, you can bypass each of the starter leads with car jump leads until you find the culprit. And you can bridge the starter solenoid connectors if you suspect that it's faulty (there will be sparks though!) Even an earth jump between battery and engine is worth trying. You can't rule out a faulty starter of course but it's usually the least likely and worth exhausting all the above before you start to suspect it. *there's nothing wrong with this getting warm or even hot after extended cranking (not advisable) - it's whether it is getting v. hot almost immediately is the clue. I helped a fellow apprentice once with a Vauxhall Viva who was stranded after work but i got him to touch all the points (as mentioned^) while I cranked. He found the problem all right! - it was the earth onto the bodyshell - think he was pleased and annoyed at the same time
