V11 Sneeze

[Kiwi_Roy]

I took my VII Sport out of mothballs over the weekend and rode it to the nationals in John Day.

 

This bike has always had a sneeze which causes it to suddenly stall at idle, it ticks over pretty good at about 1100 revs then after a few seconds sort of sneezes and stalls. By holding the throttle open a bit more it's able to spin through the sneeze.

On the long trip down and back I thought I could also detect it happening under power. I don't think it is any better or worse when hot.

 

I have tried a different ECU

Replaced the timing chain and tensioner

 

Any thoughts as to what might be causing this annoying occurrence, it spoils an otherwise pleasant bike.

 

Thanks,

Roy

[LowRyter]

Mine will occasionally do it too.  Pipes, crossover, K&N and PC IV.

 

Mine's not very pronounced.  When it coughs I just give it a little more throttle.  The key is don't lug it.  It sometimes does it when coasting but again I blip the throttle when I downshift and will blip it again if it coughs. 

 

The issue for me so slight that I just ignore it.  Blip the gas and chalk it up to the "character" of that big powerful (that's a laugh) V Twin. 

[Paradiso]

I was surprised at the negative effect on running of putting a slightly larger 'o' ring on the timing sensor.  There are shims to get the distance correct.  Maybe someone had fiddled with these. 

[JBBenson]

I have had a similar problem when on trailing throttle, i.e. closing throttle on deceleration.

 

Turned out the throttle was not completely closing, and was confusing the ECU, so it would stumble and sometimes stall when I stopped.

 

I adjusted the cables and RH grip so it closes completely and the problem went away. I also changed my riding style to make sure I close the throttle completely and not hold it slightly open with the weight of my hand.

[docc]

Roy, How many miles since the last complete tune-up (valves, plugs, CO trim set, TPS, synch) ?

 

Also, maybe good to compare the tachometer reading with the RPM seen by the ECU. There can be a large variance making us think we're idling at 1100, but it's actually 600-800 (ungood).

 

Can you get a guzzidiag dashboard up?

[docc]

BTW, here's one of the worst culprits I ever found that gave that same low speed *burp* -

http://www.v11lemans.com/forums/index.php?showtopic=12326&p=151210

[Kiwi_Roy]

I'm currently running a MyEcu from Cliff Jefferies so no Guzzidiag capability, I might be able to get it using the backup ECU

 

Docc, it's been a while but as I said the bike has always done it

I have never had the CO trim checked

 

Paradisso, I will check the gap, what's it supposed to be?

Is the timing/phase sensor 01721600 a common automotive device?

 

It's almost like it fires early the cough is really quite pronounced

[MartyNZ]

Shimming V11 RPM Sensor.pdf

I will check the gap, what's it supposed to be?

The RPM sensor gap is supposed to be 0.7 to 0.9 mm. See attachment. GuzziDiag reported the RPM sensor as failed on my bike, but I fitted a correct thickness shim, which made GuzziDiag happy again. Be sure to fit a new o-ring as you refit the sensor or you get an annoying little oil weep.

The snort you describe was the same on my bike, and was fixed by either of two things:

1/ Setting the TPS to 150mV when the RH throttle butterfly is fully closed (lower than idle). My bike was set to a higher voltage, and the snort could almost pop the throttle bodies off. Do this as part of the full tuneup Docc mentioned.

2/ Renewing the rubber hoses from the throttle bodies to the intake manifold stubs.

Good luck, Marty

[Kiwi_Roy]

Thanks for that Marty, I will check the sensor gap ASAP, bit of a task as the timing cover will have to come. I might try to measure it first with the digital calipers.

The TPS is easy enough to check again.

Intake rubbers eh, perhaps I should get a pair on order 

[Scud]

 

2/ Renewing the rubber hoses from the throttle bodies to the intake manifold stubs. 

 

 

I was thinking this too. Easy way to test this is to wrap some electrical tape around them (between the clamps). My Scura started acting up as you described - I noticed some small cracks in the boots. I wrapped then with electrical tape - it cured it and the tape is still on there after many miles. Will replace the boots at next service (already have them).

 

Of all people, Roy, I'm certain that you have some electrical tape. 

[czakky]

I'm with Docc on the tune up. Verifying idle too. Mine used to sneeze too but after a couple dozen tune ups she doesn't anymore...

[fotoguzzi]

valves set too tight?

[MartyNZ]

I will check the sensor gap ASAP, bit of a task as the timing cover will have to come. I might try to measure it first with the digital calipers.

I used a blob of blu-tac stuck to the sensor tip, then screwed it up tight. So long as the sensor is degreased and the wheel is oily, the blu-tac will squeeze to the actual gap, and still pull back out with the sensor. Then I cut away half the blob to measure the thinnest remaining blu-tac. I had to check using calipers as well, because I didn't believe the 1.5 mm gap I found.

BTW, how is your new accommodation working out for you?

[docc]

I  struggled  sooo  many  years  with  burping/hiccup/sneeze  before  a  Total Expert and Complete Gentleman  (The Perfesser-His-Own-Self Andy York) zeroed my CO. It was an absolute revelation. Mine was at "minus 27."

 

Your V11 will never run right with the CO leaned out so.

 

Do the right (guzzidiag) thing, get the cables, and check (zero) your CO.

 

This is Step #1, before all else.

 

At these low, idle/off-idle speeds, also consider tuning with the air bleed screws out a full turn rather than the factory specified 1/2 turn (never could get that to work!)

[Kiwi_Roy]

So Guzzidiag sets the CO,

 

how does that work there is nothing in the ECU to measure O2 or CO

 

I thought you would need to be hooked up to a fancy analyzer.

 

 

Marty,

          Our apartment is built on the Penitentiary Reserve, we are just behind the old gatehouse, fortunately the stone walls have been removed

and I am free to come and go as I please.