VFR 800 '98 possible grounding issue?

Hi,

I bought a (seemingly) well-kept '98 model in november. As I'm from Norway, I'm just now bringing it out on the road. Had my second trip on it yesterday, and when I brought it out it started and ran just fine. After a 10-15 min run, I had a short stop where I killed the engine. When I tried to start the bike back up, it failed as if the battery was low - cranked once or twice before dying out, with the electronic panel and lamps (oil/natural) giving out as well.

It started fine with a running start, and ran just fine.

After driving it back home I also noticed that the fan does not start. The temperature seemed fine while running (~75 C ~170 F), but increased to over 100 C (200 F) after turning the engine off. The fan never started, whether the ignition was on or not.

I measured the battery to 12.49 V, but the bike still failed to start as if the battery was low.

Does this seem like a failing grounding cable? If so, where should I look for the issue?

I did some brief googling and found that there could be some grounding issues. After taking off the cowl I found the large connector on the left side. I couldn't find any clear damages or burnt pins. Went over the easily accessible wires with some electronics cleaner, removing/cleaning/reattaching the different connectors I could find. However, nothing changed and the bike still wouldn't start, and the fan did not start running (although it had started to cool off naturally at this point).

I'll see if I can't add some pictures later today.

 

The grounding issue with the 5th gen VFR often occurs in the common ground block. This is a rectangular block approx 1.5cm square and is taped into the main wiring loom on the left side, below the saddle and behind the tail cowl, around where the alternator 3p plug is located. Dimming lights and instrument lights that blink with the turn signals are common symptoms.

It is always a good idea to check the ground cable from the battery to the chassis is clean and tight where it bolts to the chassis.

A moving temp of 78-82C is normal, and rising to 100C when stationary is also normal, and the fan should cycle on/off at around 102/98C. The fan issue is likely unrelated; the thermoswitch completes the path to ground for the fan motor, so to test just pull the spade terminal off the thermoswitch and jumper that to the chassis, with the ignition switch on that should make the fan run. Check the fuses if not, and also check the fan does not have debris stopping it spinning freely.

Your symptoms sound like a failing battery to me; it is normal for the battery to work better cold than hot if it is developing an internal short. It can show the expected volts but lack the current to start the bike. In the first instance I'd suggest a new battery, you could use a jump cable off another 12v source e.g. a car, but if the bike's battery is internally shorting that may not always be enough to start (hot jump cables will result if that is a problem). Try again without the bike battery in the circuit.

 

Have the battery load tested. Sounds like it has been mostly dead all day.

 

It could be a bad battery. I had a similar battery failure recently where trying to start it caused an instrument panel reset, but I was able to bump start it with a running start letting out the clutch in 2nd. I was able to make it the 75 miles home.

You should also check charging voltage when the bike is running. See a service manual or read this thread. http://vfrworld.com/forums/showthre...mon-regulator-Stator-failures?highlight=drill

The fan doesn't cycle on until around display indicated 220F on my VFRs. If you do jump start the bike from a car, make sure the car is off. All you want is the vehicle's 12V battery to start the bike, not any additional power from an alternator. Do not jump start the bike from a running automobile.

 

Thank you all for the replies!

I tested the battery yesterday, and found it to drop to ~9 V when hitting the starter. Going to change the battery today, and hopefully that'll be it.
This was also after a night of charging, so the battery was topped. It did start the bike fine, but I'm assuming it'll have the same problems after a short run.

I also went over the fuses and connectors visually, and couldn't find any indications on any of them being burnt out. If a new battery doesn't solve the problem I'll go back in with the voltmeter to check them thoroughly!

As for the fans not starting, I guess I'll have to pay some attention after a run and check that it starts if the bike reaches ~102 C as mentioned.

Again, thank you all for the replies! Really looking forward to getting the bike properly out on the road!

 

You will need to pull the tail plastic, but look at the connectors coming off the voltage regulator if you haven't. Especially the one carrying the 3 yellow wires from the stator, as that is usually the first thing to get crispy.

 

I'll bite. Why not? Voltage is 12 regardless. Amps are pulled. I always jump from a running car...and without issue.

 

Voltage will be above 12V at whatever the alternator is doing. I've read numerous sources over the years saying there is a risk to overwhelming the bike's electrical system. Probably nothing will happen, but it isn't worth the risk. A car battery should easily be able to fire off a bike on its own, no need for the car's charging system to be involved.

 

If a good car battery alone can't jump a motorcycle, you've got issues. No reason to have it running.

 

Alternator on a car will supply too many charging amps, and m/c batteries should be charged at 2 amps max. Just leave the car shut off........

 

Amps aren't supplied (pushed), they are pulled when needed.

 

https://ricksmotorsportelectrics.com/blog/jumping-a-motorcycle-with-a-car-should-you-do-it/


In the end, you should only rely on a jump from a car if you are in a really desperate situation. In most cases a jump from a car to a motorcycle would probably work fine but if something is just slightly amiss you could have a much greater problem on your hands. If you are in a position where you must jump a motorcycle from a car, make sure to turn the car off first.

 

I get it. Folks have been spouting that for decades, but no one seems to know why. And I've never heard of a bad result. I'm trying to understand why because....amps are pulled.

 

My take is there's no reason to expose the motorcycle's electrics to a potential higher voltage condition of the car's charging system. A good car battery is going to be maintained at 12.6 - 13V. The car doesn't need to be running.

Another source, Yuasa. https://www.yuasabatteries.com/resources/guides/motorcycle-battery-jump-start-guide/

1. Connect the red positive terminal on the dead battery to the positive terminal on the live battery.
2. Clamp the black negative terminal on the live battery, but make sure you place the opposite negative clamp on a grounded and unpainted metal surface of your motorcycle. Typically, the chassis is suitable for this.
3. Start the motorcycle with the good battery. Do NOT start the car.

 

I give.