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Discussion Starter · #1 ·
Hey guys, I've got a few issues with my '05 919, it's completely stock except for some delkevic slip-ons. Also just to note these problems were present with the stock mufflers.

Firstly, the bike rides/idles fine when cold/warming up, when it reaches temp the idle starts to get pretty rough, it climbs then drops, and vice versa. It drops a good 3-400 rpm then evens out periodically, then continues fluctuating. It sounds and feels awful.

Secondly, when riding the bike warm it tends to stumble/lurch/backfire, for instance when holding the throttle to keep a steady speed it lurches and stumbles, occasionally backfires, it's never a comfortable ride as you're being jerked around in your seat. Acceleration is not consistent, it hesitates, stumbles and backfires. Deceleration causes backfiring.

Finally, the bike cuts out while riding, usually the lurching/stumbling worsens and the bike just shuts off. FI light comes on, ignition does nothing, all other electrics work. Switching the key off and on fixes it. It's not a uniform, predictable issue, it could happen 2 minutes down the road, or an hour.

The first time the bike switched off on me it was raining, I was only 2 minutes down the road, I came to a stop and the HISS light flickered along with a relay of some sort rather quickly, that stopped, I tried to start it but the ignition did nothing, no crank. So I switched the key off and on and continued, bike started fine. It died again after another few minutes of riding, conveniently as I came into the driveway...

If anyone can shed some light on what might be the issue I'd be very grateful!
Cheers guys
 

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Finally, the bike cuts out while riding,
I tried to start it but the ignition did nothing, no crank. So I switched the key off and on and continued, bike started fine. It died again after another few minutes of riding, conveniently as I came into the driveway
Sounds like a weak battery. How old is your battery? That's the first thing I would test/replace.
 

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McTavish
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6,570 Posts
Odd combination of gremlins, that's for sure.

1
What was the most recent work done on the bike?
Always revisit that.

2
It sounds purely electrical in nature, not fueling, not electrical and fueling.

3
Is the ground strap to the frame, hidden by the gas tank, intact and bolted in place?

4
Do as dial suggested, as in test before buying a battery.
Voltage across the battery terminals before starting.
Voltage drop check across the battery terminals as you start it.
Battery voltage recovery check a few minutes after just starting it and killing it.
System voltage check @ 5000 RPM (when the alternator reaches its peak output)

5
Maybe the main key switch is (also?) involved.
 

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Discussion Starter · #6 ·
Odd combination of gremlins, that's for sure.

1
What was the most recent work done on the bike?
Always revisit that.

2
It sounds purely electrical in nature, not fueling, not electrical and fueling.

3
Is the ground strap to the frame, hidden by the gas tank, intact and bolted in place?

4
Do as dial suggested, as in test before buying a battery.
Voltage across the battery terminals before starting.
Voltage drop check across the battery terminals as you start it.
Battery voltage recovery check a few minutes after just starting it and killing it.
System voltage check @ 5000 RPM (when the alternator reaches its peak output)

5
Maybe the main key switch is (also?) involved.
I bought the bike second hand in October last year, unsure of the work thats been done on it frankly. Since owning it, I've had its 24k major service done - I queried the problem with the dealership mechanic, he plainly said "the pipes are too open"...

It does strike me as being electrical aswell, the ground is in place. I did test the battery some 5 months ago, and it was healthy, but even then the problems existed. My knowledge of mechanics isn't great and I feel I've exhausted it, I'm at my wits end hahah
 

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919 Rider
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Check your ignition coils. The wires providing power to them are only held on by small connectors which push onto tabs. They can work loose.
When you first start the bike up quickly check headers are warming up evenly.
 

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Discussion Starter · #11 ·
Sorry I've been a bit quiet lately, haven't had too much time to poke around.

I took the tank off a little while ago, so I'll do all of the running tests when I get it fitted again. Yesterday I was looking for any voltage/resistance anomalies with a multimeter, am I right in thinking that the voltage at different points around the bike should be the same as the voltage across the battery terminals?

If so I suspect the issue could be a grounding problem, battery voltage is 13.04V at rest, every point I checked throughout the bike measured 13.04V, except for a few points around the headlight/cluster subframe which came back consistently with a voltage of ~12.4V, I'm not sure if this is indicative of a potential problem.

I have to add some observations for the cluster and headlight, the gauge needles on the tach/speedometer reset occasionally, very randomly I must say, the headlight flickers ever so slightly when the bike idles aswell. Which peaks my suspicions about a potential issue in the front end.

The indicators also tend to stumble on occasion? For example I activate my right indicator, and its response is delayed, I won't see an indication on the cluster for a second, then it'll pick up and carry on as usual.
 

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Discussion Starter · #12 ·
Check your ignition coils. The wires providing power to them are only held on by small connectors which push onto tabs. They can work loose.
When you first start the bike up quickly check headers are warming up evenly.
I checked the connection on both coils, and both were fitted.
 

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I agree that it certainly sounds like a ground issue. Possibly pull the seat, side panels, unbolt the tank, start it and go to wiggling wires.

The only other thing I can think of is the bank angle sensor and/or the wiring going to/from it? I believe it cuts ignition so any problems on that circuit could case the bike to shut off.

Good luck. Wiring gremlins can be a real pain.
 

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Discussion Starter · #15 ·
I agree that it certainly sounds like a ground issue. Possibly pull the seat, side panels, unbolt the tank, start it and go to wiggling wires.

The only other thing I can think of is the bank angle sensor and/or the wiring going to/from it? I believe it cuts ignition so any problems on that circuit could case the bike to shut off.

Good luck. Wiring gremlins can be a real pain.
I'll check the bank angle sensor, cheers!
 

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Discussion Starter · #16 ·
Okay I did some testing today,

The main ground on the right hand side of the frame under the tank was a little corroded, I cleaned that up, put the tank back on, and started it up. The idle was very smooth to my surprise!

I took the following measurements:

  • Before turning on ignition, 12.97V
  • Before I started the bike, with only lights on, 12.4V
  • Voltage dropped to 10.7-11V when started
  • Across the terminals when warm, 14.2V at idle ~1300rpm
  • Voltage recovered to 12.88V after a few mins, 12.92 after 5-10 mins

After these measurements I took the bike for a quick ride, no sputtering/stumbling, little bit of backfiring, bike didn't shut off. Felt fine to ride.

Tested the throttle position sensor afterwards, with ignition ON, engine OFF

  • y/r wire to ground measured 4.99V
  • r/y wire to ground measured 0.03V
  • y/r wire to r/y wire measured 4.08V

These voltages remained the same at all throttle positions with engine OFF, not sure if this needs to be tested with engine ON... If it doesn't, this could be and issue?

Next I tested the bank angle sensor, with ignition ON, engine OFF

  • Battery voltage at 12.35V (ignition was on for my lengthy tests..)
  • the 02/03' shop manual states the voltage between the white and green wire should be battery voltage, it was 11.38V
  • red/white wire to green measured 0.38V

It operated properly, triggered the engine stop relay when tilted either side.

After a few hours of messing around I started the bike up again, the battery voltage was low considering the amount of time ignition had been on. 12.35V.

The bike started fine, but the rough idle returned, fluctuating revs up and down, lights dimming. Didn't ride it though.

  • Cold idle was roughly 12.7V and climbed up to the warm idle temp of approx. 13.1V
  • Voltage peaked at ~13.6V when at 5000rpm

I know I should've done this when the battery was properly charged/recovered, but to me it seems quite low regardless.
 
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