Hi guys so I started work on a 749 I got recently, after fitting the new battery and turning the bike on. I noticed the voltage readout dropping and the bike would not start cranking. There was a optimate lead on and another connection coming off the negative contact, I removed both of these and the bike did not drop volts and started cranking correctly. I then connected a newish optimate cable and the bike behaved as it should again. The odd thing was the other cable(non standard) was connecting to the ecu mounting bolt. I initially thought it was part of an alarm system as I recieved a fob with the bike, but after getting the panels off I could see no additional connections, or control/speaker box. many ideas on this cable as on my other 749 a connection like this was not present. cheers excuse the contacts, I’ll have to sort them out soon, top pic of how the cables were originally
After putting some fuel in the tank and trying to start the bike, the bike try’s to start but I’m not hearing any thumping from the engine, I can see the clutch spin slightly with each crank and there is no fault code showing. I’m charging the battery again now and will try again with the earth from the ecu attached. I have started from an empty tank, will this effect the initial flow to the engine?
Hi Yes pump primes, I then press the start briefly and it begins the starting sequence. Sounds like my other 749 just with no thump. I’ve been scouring some of the forums and I’m going to try and get the corrosion off the earthing terminal, if that does not help I will move onto the plugs.
I'm Guessing the bike has (or the Previous owner thought the bike had) earthing problems And have tried to strengthen the earth point to the ecu by earthing it to the battery, i've done this when i was trying to solve the earthing problems on my multistrada and it did help for a short while. i would check your engine earth point condition and maybe run another cable from the battery earth to engine earth point ( a Cheap car earth cable £6ish from halfords would work) and see if it starts then.
Rather than running to the existing earth point, run the additional earth lead from the negative to the visible bolt for the starter motor.
No, secondary heavy duty earth lead. Should improve starting. The starter is held by 3 bolts. Two of those bolts are hidden by the engine cases. Attach to the one bolt that is visible.
I’ve ordered a couple of earthing wires from Halfords, hopefully should be here tomorrow. I did sand off some of the corrosion and trued again with a fully changed battery, when starting I did hear it thump and the the clutch started to rattle abit more, so looks like it might be the bad earth, my rear indicator started intermittently working, so there is a bad connection there aswell. Still no fault codes but the key code icon does pop up briefly.
So with a fully charged battery and the second earth to the back of the starter as Chris said, the bike turned over but only stayed alive for a few seconds. Dash did read -3 though. I’m charging again now and will try again shortly. I think it’s a combination of my battery being inadequate and the earth corrosion. I will order a better battery and some cables from @Exige next week. On a positive note, I received a new book!
Is the battery holding charge under load? it should read well in excess of 12.4V and be able to hold that with the bike’s lights on (engine not running) for at least 5 mins.
Suggests to me that the battery is borked. Here’s my general battery spiel (don’t think I’ve posted it in this thread before): Batteries. There has been a fair amount of discussion on various pages about batteries and them failing. And blaming this bike or that bike or whatever. So anyways here's a bit of science. I'll be using the battery from my MV F3 as an example. This is an 8.6Ah battery. Your battery is probably bigger (physically) than this. What does this mean? Well, it means it can deliver power equivilent to 8.6Amps for 1 hour, or any combination thereof. 1A for 8.6hrs for example. This is a huge simplification as the temperature of the battery (there is less available charge when cold), and the actual current draw (it becomes less efficient the higher the current draw) all affect things...but it'll do as a start. Now - unless there is a fault on your charging system (see the end for how to diagnose) if the battery fails it *is not* the fault of your bike. No matter what the make of the bike. If an automotive battery drops below 10V it is probably toast. How could this happen? Well, lets say you have an alarm - say the alarm that was on my old R1 - a Ross Meta 351A. This draws 10mA when armed. So, this tells me that in 860hrs the battery will be completely drained if there is no charging going on. However, the battery will be completely killed long before that - if a battery gives up around 3/4 its charge without recharging...it'll probably be good for nothing soon after. So...in 645hrs of not riding the battery is knackered. Just over 3 weeks. Less if the weather is cold. Like winter. When we don't ride. You might be able to recharge the battery and "recover" it - however it won't hold as much charge as it used to. On older bikes this wasn't such a massive problem - as you switched them off, and then they were off - any alarms aside. But modern bikes have ECUs that are "smart". They hold custom maps and a clock and trip counters and all that - that is stored in RAM and needs power even when you switch the bike off. So, put an alarm on a modern bike - and hey, lets have a tracker too and you're probably looking at 45mA drain...on my F3 that means just under 8 days before the battery needs replacing. This is why my MV came with a battery trickle charger. But but, you shout, I keep my bike on a trickle charger and the battery still died after 18mnths....WTAF?! Well, consider this - at the dealer where you bought your bike. Were all the bikes on trickle chargers? Didn't think so. A good dealer will uncrate a bike, fully charge the battery before connecting it, do the PDI and then disconnect the battery - and fully charging the battery before storing it. And only reconnect the battery when the bike is about to be driven away sold. And when they get a second hand bike in...they'll do the same. If your bike was sitting on the shop floor for a couple of weeks with the battery connected....yeah...you will need a new battery. How to test your battery (see attached image). And to test your charging system - start the bike and rev the engine to about double idle speed (I was going to say 5000RPM, but that'd screw with big v twins etc)..the voltage across the terminals should read above 14V and below 15.5V If it is below 14V it might be that your battery is quite flat and is drawing all the charge it can take - but if the battery is fully charged then it shows that either your generator is knackered or (like in my 20yr old RVF) the original wiring loom is rubbish and taking too much power or your reg/rec is borked and giving nothing out. Get someone to look it at and check it out, your battery will keep going flat if you don't. If you're reading above 15.5V chances are your reg/rec is on the way out - get this fixed ASAP as it will boil your battery (cheap to replace)and possibly burn out your ECU (not cheap to replace). Oh, yeah. Even if all the above is perfect, absolutely perfect - batteries die with age anyways after around 3 or 4 years. They are a consumable item. Hope this helps.
thanks for this! The battery I bought was a cheap one, do you have any recommendations? Or stick with the relevant yuasa.
