Hi all, had a strange issue at the wkd. Bike started perfectly, took it for a run. Got home, switched off the ignition for a couple of minutes and then attempted to restart to put away, but got a strange sound; engine did not turn over. Checked battery voltage 11.3v Tried several times but decided to pull the battery (which is approx 12-18 months old) and charge. Charged battery installed, it restarted fine. So thoughts turning to the possibility that the charging system is not working correctly, and the bike was actually (possibly) running on battery power. If that's the case, I could have ended up in trouble on a longer ride. Following the Haynes manual, I checked the output from the alternator. At idle it showed 11.91v, rising to approx 13.5v when throttle increased to 3k (Haynes says it should be 13.5v to 15.5v). With that throttle position held, the voltage then dropped back gradually to the idle voltage again. This doesn't seem right to me. Appreciate any thoughts. I am hoping the alternator hasn't gone bad.
Sounds like the battery is not in the best of health, you should be showing 12-12.5 volts on a healthy fully charged one Probably a good idea to check out your solenoid and starter connections and the main earths for good clean connections as the standard circuit was only just adequate when new !!!
That sounds very much like the reg:rectifier has died with the voltage dropping down when reving up. I had this on a bike recently. Hope this helps.
Thanks, checked this morn and found this connection a bit loose and also with surface corrosion. Photo of it going back in after cleaning up the surface. Will try the output test again and see if that resolves. If not, then I'll replace with a spare trusty RR51.
If your inclined to spend the time, I'd also check out the stator to regulator wiring, as the bad earth might have caused some issues and these can get crusty without any additional help.
Thanks all. Cleaning up the above reg/rec earth seems to have solved the problem. Now holding 14v to 15v at 3k, and not dropping off. Will methodically check all other connections as suggested. The starter wiring is all good at least, replaced recently with 16mm marine grade leads!
Looks like my fix above did not resolve the problem as I thought! This ended up in a total disaster yesterday. Broke down 100 miles from home and, after a terrible recovery service from Swinton insurance, I got home with the bike at midnight after a 5 hour wait by the roadside! So back to the drawing board with more tests to find out what the heck is going on. Exactly the same symptoms as before. Press the starter and a slight sound but no engine turnover. Some clues - in the final 10 miles as I approached my destination yesterday, the bike started popping a bit and losing power, almost like fuel starvation, but then seemed to pick up and ride through it. Seemed ok by the time we arrived at the bike stop, although I should have investigated immediately upon stopping, instead of being focused on coffee and flapjacks. Could have expedited the recovery at least. I think the charging system must be at fault. I will try installing the RR51 reg/rec which I have held onto. And maybe even just get a new battery, although I'm not convinced there's anything wrong with that. It's like the bike is pulling directly from the battery to generate the sparks. And, as the battery begins to run out of charge, it begins to struggle. I could be wrong, but I have experienced this before on my first SS, when the bike eventually ground to a halt and broke down. Cause was a fault reg/rec. Oh BTW, a jump start using jump leads connected to another bike made no difference either.
Just had a few problems with my charging system - entirely self inflicted, it's a bit embarrasing but I will up date my reno thread so others may benifit from my stupidity. Anyway, have you checked stator resistance, think 2-4 ohms, also continuity between both wires (sorry I am presuming 2 wire single phase) and no continuity between either wire and earth/engine. Sorry don't know how to check 3 phase. Cheers Gaz
Apologies for keeping this thread going, but I seem to have an ongoing battle with this issue. My bike seems to be running purely on battery power - once the battery is depleted the bike stops. So yesterday I have been through the Haynes manual on checks Battery showed 12.57v initially Leakage Test Leakage test showing zero so that's good start Alternator output test Started the bike and ran for a bit, battery showing 12.07v at this point. Increased the revs to 3000. The voltage did not rise at all, initially. However, it did then subsequently increase gradually up to 13.97v at around 3500 revs. Haynes says 13.5 to 15.5 is the required range. So this tells me that there is charge reaching the battery? Alternator Stator Coil check I checked the resistance between the two yellow wires from the alternator. Resistance should be 0.2 to 0.4 ohms according to Haynes. My meter doesn't have a 1 ohm scale, so I had to set on the 200ohm scale, which read 2.5 to 3.0 first time. So this is a useless reading. Then when I checked again and it was showing 0.5 ohms. This was between the yellow wires (-ve probe on one, +ve probe on the other) Continuity between each wire and earth indicated a reading of 1. I don't know whether that's correct or not? Regulator/Rectifier Just to rule out the reg/rec, I replaced this with a brand new one (which I needed for another build anyway), but this made no difference to the voltage showing on the battery terminals when revved. I will say one thing, the two yellow wires from the alternator were quite hot even after a couple of minutes of the engine running. So that says to me there is good voltage being pumped out. My meter doesn't appear to check AC voltage, so how do I check the exact output? Also, when the engine is running, it doesn't seem to run evenly - this may be as a result of the above issues. Perhaps because it's pulling the sparks directly from the battery power? Is there anything else I can check before I hand the bike over to a specialist?
Trace the alternator to reg wires and check for breaks crusty bit’s & previous bodges . My 916 had 3 crappy connections bodged in from alternator to reg. The 2-phase charging system isn’t the best so struggles if key components are a bit off/corroded/bodged. Also ensure all 12V battery & earth cables are decent (replaced if oem) and have clean sound connections.
I would first test the multimeters continuity by touching the 2 probes together, that should be the expected result when you test the 2 yellow wires. Does your meter have a beep? Also, does the 1 show up on the lefthand side of the screen? I think this means no continuity. I think you can also check continuity on the lowest setting for resistance. I put it on 200 ohms setting and got 0.1 touching probes and 0.2 on yellow wires. Cheers Gaz
Could it be that V.reg is fine when cold but failing when hot? Difficult to replicate without running it but could maybe heat V. reg with hot air gun and see if charging voltage drops off? I had this problem on an St2 many years ago.
Get a 300cca LiFePO4 Shido with a Mosfet r/r and upgraded starter/solenoid cables from Exact Start UK and never dread starting your Duc again...
Absolutely. The LiFePO4 is the safest type that doesn’t burn when it fails, unlike the Li-Ion. https://lithiumhub.com/lifepo4-batteries-what-they-are-and-why-theyre-the-best/
Battery: I've gone back to Yuasa, as they are easy to live with and reliable. My Motobatt lasted a year before it expired.
