V11 Sport 2001 intermittent stalling

[Tinus89]

Hey all,

 

 

I need some help. After the total rebuild of my engine, I drove the Sport for about 500km, no issues. Checked valve clearance again, oil level etc. Yesterday I went on a rather spirited ride with some of my co-workers. Weather: half sunny, 21deg C.

The following sequence of events happened:

 

- After a sporty drive, stop and (by accident) kill the bike using the side stand in gear. I want to relocate the bike and try to start it again (in neutral). The starter just turns the engine through one compression cycle slowly and stops, just like with an empty battery. I leave the bike for 5 min and decide to try again, and she starts up like nothing happened.

 

- After the second sporty drive, idling trough a city for a bit, some traffic lights, the pace pics up again (~60km/h). A roundabout without stopping, acceleration and then at around 70km/h, she just dies. Nothing. Try starting: she wants to fire up, idles roughly and then (or when I open the throttle) dies with a bang in either of the exhaust.

 

- I wait for help (40min) and when help arrives, I start and she fires up like nothing happened. After a 10km tail, the help says goodby and I drive on (20km), until I have to wait for a traffic light (2min). Accelleration again and again at around 70km/h, she starts sputtering and dies. I decide it may be a heat issue and let her cool down (20min).

 

- Start, rev a little, OK again. Start driving, about 10min, doing a steady 80km/h for about 2min and again: sputtering and surging. I had to keep her going because I couldn't stop, and eventually blew off the right intake boot. Brought her home on a trailer.

 

What I did:

Move all relays one position, no succes.

Check tank vacuum: OK.

Check ground lead to gearbox, secure.

 

What I will do:

- ECU Error readout

- Visually inspect full wire harness

- Check connections under fuse box and relay box

 

What else can I do?

- Can the no hot start have damaged anything or be related?

- Only thing I changed since last drive and before this one, was replace the starter switch (which I damaged in my fall) and tidy up wiring.

- It does not seem to be vapor lock, as she also died at speed and it was not too hot outside.

 

 

Sorry for the extensive story, but I really need help where to look and want to paint a proper picture of the issue...

 

[czakky]

How does you ignition switch look? It's a good idea to take it apart and clean it/lube it every now and again.

 

What is battery type/age?

 

I'm sure you've checked running voltage.

[stewgnu]

Plugs and battery terminals good + tight?

[Bbennett]

All good advice above - especially checking battery terminal connections for tightness. 

 

I suppose there could be a fuel quality issue too - but the symptoms do not line up perfectly for this being the culprit.  Sounds heat or vibration related.

[swooshdave]

No one mentioned this but maybe the side stand switch? Bypass it and see if you still have a problem? That's where it seems to have started.

[docc]

No one mentioned this but maybe the side stand switch? Bypass it and see if you still have a problem? That's where it seems to have started.

You can bypass the Sidestand Switch by simply shifting into neutral.

[MartyNZ]

It could be a problem with your relay bases. The terminals that connect to the relays can be pushed back, or get loose. Then road vibrations can make a connection between a relay and the terminals in the base fail intermittently.

KiwiRoy wrote a helpful guide on how to fix this problem here: http://www.v11lemans.com/forums/index.php?showtopic=15718 

[swooshdave]

 

No one mentioned this but maybe the side stand switch? Bypass it and see if you still have a problem? That's where it seems to have started.

You can bypass the Sidestand Switch by simply shifting into neutral.

 

 

And then you could have a bad Neutral switch? Do you remember the good old days when the fanciest thing you had to worry about was if your Boyer was going to fire?

[Kiwi_Roy]

The Starter turning the engine slowly worries me, I have seen that before when the main ground was loose, the starter current finds an alternate path back to the battery via the small black wire from the regulator case to negative post. The starter turns at less than half speed and pretty soon the bike starts letting out the magic smoke like this one has.

(sent to me by an owner complaining of slow cranking and smoke)

 

Make sure the main ground connects to a gearbox bolt down near the seat release like this c/w Vaseline of course.

 

Not under the seat release bracket like this (my bike), it was loose and slow cranking as I described

 

 

Loose (disconnected) main ground at the battery

Lead Oxide is formed on battery terminals, this is an insulator that can completely disconnect the lug from terminal even though it's mechanically tight, I have seen it disable a bike in as little as 2 weeks. The oxide creeps into the connection between post and lug until all that's left is a tiny area of contact which usually fuses at cranking, I'm sure you've all experienced this in an auto in winter time.

You may have noticed when measuring battery voltage, just touching the meter leads on the post doesn't make connection, you have to jab the leads through the layer of oxide.

Scrape the lead terminals then smear them with Vaseline to keep the oxygen away and they will maintain good contact for years.

 

A loose ground could also explain the erratic running, these bikes won't keep running without a battery connected.

 

Yes, clean the ignition switch, that's another spot the battery can be disconnected replace the old grease with fresh Vaseline. (no other)

 

 

I hate to say this but if you had a Go Winkie light it would be flashing like crazy

[Tinus89]

How does you ignition switch look? It's a good idea to take it apart and clean it/lube it every now and again.

 

What is battery type/age?

 

I'm sure you've checked running voltage.

 

Battery type/age I would have to get back to you on, I only know it's a Yuasa and the age will remain a mystery (P.O.).

Running voltage wás around 14v @3000rpm, but I will check again áfter the failure.

Battery terminals are clean and tight and put together again 500km ago.

 

What ignition switch? The key switch? Or the one near the throttle?

 

 

No one mentioned this but maybe the side stand switch? Bypass it and see if you still have a problem? That's where it seems to have started.

 

I guess I could bypass it. It was replaced just before the ride! However, would that not cause it to not idle at all? Instead of rough and spitting and burping?

 

 

Which exact cable should I look for to be loose? The one on the gearbox definitely is secure. Which wire will take over if there is a bad ground?

 

Are the coils one system or two separate ones (can both fail at once or not?)

[czakky]

Ignition switch is where your key goes under the dash. There are a few contacts in the switch itself also check the solder joints while you're there.

 

As Roy said remove and clean the main ground (gearbox wire).

 

Two coils, up front by the oil cooler and horns.

[Gio]

It wouldn't account for the slow cranking, but some symptoms do remind me of vapour lock ... stopping after a spirited ride, the sputtering and re-starting ok after allowing to cool down - although this would not normally happen whilst underway when there is good air-flow. Is there good clearance between fuel lines and cylinders?

[fotoguzzi]

The Starter turning the engine slowly worries me, I have seen that before when the main ground was loose, the starter current finds an alternate path back to the battery via the small wire from the regulator case,

common fix is to add a ground wire from the regulator to engine block. the reg is grounded through a captured nut and can loose connection intermittently.

[Kiwi_Roy]

No the ground at the regulator is to fix charging. Slow cranking is a symptom of loose main ground which causes the ground current to divert to the regulator ground causing it to get red hot as the bike cranks over slowly as shown in first photo I posted
 

The speed of a motor is proportional to the current through the armature, normally a VII passes 150 - 170 Amps imagine how much Voltage an extra 1/4 Ohm of resistance drops at that current LOL

[Kiwi_Roy]

For goodness sake wire a small light to the petcock fuse and chassis tape it to the bars, that will eliminate 50% of the possible faults, that's all I am going to say.