Has anyone encountered problems with their tacho on the 02 ST4s? Mine suddenly started to vary hugely, reading anything from 2000 to 10000, while I was cruising at 70mph. Now if I try to rev the motor hard, it feels as if the rev limiter is kicking in & cutting the motor. Any ideas please?
Whip out the tacho and you'll find three little brass screws behind it. Give them each a little nip up. But it is also worth taking out the pickup sensor and giving it a good clean. That will usually sort it out. A
I'd check your charging system. Tacho only works above a certain Voltage threshold. If you have charging problems it will give the results you describe. Pat
HI, I followed Ascalon's advice & it seemed to work while the bike was in the workshop, with the lights off. However on a test ride, with the lights on, the problem is better but not cured. As I just came back from holiday & the battery was flat & starter motor speed is not brilliant I have bought a new battery, which I'll fit today. Thanks for advice, charging problems, generator/regulator are next??
Sorry to hear you've still got issues, but yes it sounds as if it might be a voltage issue too. Check your reg/rec and make sure your primary earth is good. Battery leads can get dirty and corrode too, so worth cleaning.
Hi I fitted a brand new battery & now all is well until I put main beam on. Today I ordered another voltage regulator. I'm hoping this is the problem, as the generator is a more complicated & expensive job. I'll let you know
Check for shorts too, my tacho wouldn't operate when the lights were on, I can't remember if it was the dipped beam, main beam or both. It turned out to be a short in the tail light loom.
@Blackjack: do you mean that you are going to try a new reg/rec? AFAIK, that only controls the charging voltage from the genie back to the battery. I don't think it has any effect on the voltage that would go to the tacho. But then again, I'm an electrical numpty. A
When the battery volts drop the first thing to stop working is the tacho. I'd measure the voltage across the battery with the engine running, with both lights off and lights on. It shouldn't fall below 13.5V with engine running anything faster than a tickover.
Hi, thanks for that, problem is I have bought another voltage regulator (2 pin) & I know this sounds silly but I cannot locate the old one to change it. Does anyone know where it lives Mine is an 02 ST4s, Thanks
I thought they lived under the battery. Some people have moved them away from the heat of the engine as this is thought to give them a hard time. So unless you have had it from new a previous owner may have moved it. Follow the yellow wires out of the alternator, they have to go to the regulator next.
The ST4s regulator lives in the nose cone under the headlamp and it is a 3 phase one with 3 yellow wires from the alternator and has 2 red wires and 2 black wires out. The 2 red and 2 black each go down to a single red and a single black at the connector. If the replacement only has 2 yellow wires it's a single phase and no good.
The Regulator lives under the headlamp, behind the alloy air vent. I changed it, after a faff with 2 male connectors but exactly the same. Checked all earth connections, no joy. I'll just have to hope it's OK for Silverstone on Sunday. Thanks for all the help
Thread hijack: I've just started having similar issues on my ST2. While in Europe this weekend,noticed the tacho needle was fluctuating wildly. Ok for the first few minutes after start-up,then all over the place. Putting lights on improved matters. Headlight/neutral light brightens as revs rise. Occasional backfire after low throttle openings,(while filtering etc). Haven't checked charge rate yet,assumed this was the reg/rec on way out?
