Spitting and popping..?

[Gio]

I removed the gas tank over the w/e (in order to increase pre-load on the rear shock) and after putting it back on went for a test ride - the the additional pre-load certainly firming things up as intended (fully loaded sag down to 30 from 33mm with 2 full turns on the adjuster - I'll try to find the thread on this and add).

 

The bad news is that whilst setting off under moderate power I have all kinds of spitting / mis-firing / popping until I get up to speed, at which point everything seems ok again (ie pulls hard and clean when at speed, just not when getting up to speed). Very bad.

 

As far as I can recall, the only items disconnected/re-connected were the two fuel hoses, two electrical (level and solenoid) and two drain tubes from the filler. I also checked the air-filter which was clean.

 

I had to trim the end of the hose from the regulator as it had become a little ragged but it went back on ok (I thought I may have allowed some crap to get in but am usually carefull about this and cover the ends of disconnected hoses with tape whilst working...)

 

I have a long trip coming up next week (how do they know..?) so need to nail this glitch asap

 

Ideas or suggestions anyone?

 

Gio

[dlaing]

1. Perhaps you pinched a line. The line going from the tank to the pump if bent too much could restrict flow. The line going from the pump to the filter could possibly get pinched under the tank.

2. air cavitation, not sure what to do about that. I suspect it will work its way out, but you do not want to burn a valve....Perhaps fill up a full tank and run it up to the speed where it runs fine for a few miles.

I am on the third day of changing my filter. Maybe I will experience the same problem...

Perhaps the filters need priming. Because the filter and pump are horizontal I suspect they will cavitate, but eventually the pump should pump the air out, I guess....

[Mike Stewart]

The only thing I can add is: check the sparkplug wires coming out of the coils. Sometimes they will work loose when removing the tank.

 

Mike

[docc]

Turning the key on and off a few times should purge the fuel delivery system without having to run the bike.

 

Also, Gio, is the tank pulling a vacuum? Check this by being sure the cap will open without suction.

[Gio]

Thanks for all the suggestions - I will be trying these later and will advise.

 

Gio

[Gio]

So I removed the tank again and checked the hoses, plug wires etc and all seemed ok. I pulled both plugs which appeared the normal brown colour (ie no evidence of any fouling) put everything back together again and went for a test ride - still have the problem!

 

I checked for tank suck (no evidence) and even briefly ran with the tank cap open to double-check. It's almost like the sync is way out..?

I rode for around 30km but the problem still persists.

 

Any other ideas?

 

Gio

 

(PS - Power to the fuel pump is restored once the kill switch is on...must learn how to use those symbols...)

[dlaing]

Here is another possibility, could you have put the filter on backwards?

The arrow on it should point towards the line leading to the fuel injectors.....

[Gio]

I did not remove the fuel filter - just the air filter for inspection / ease of access to the rear susp adjustment.

 

Has anyone else found the need to "prime" the fuel system following removal of the tank? I would not normally expect this to be necessary but given other related threads (proximity of pump to cylinders, near horizontal orientation, tank suck etc) I'm wondering if this could be the culprit?

 

I will be working on the bike again later if anyone has any flashes of inspiration.

 

Gio

[jrt]

Perhaps the TPS got tweaked?

 

One other suggestion- there's a small vent tube just under each throttle body/intake manifold. Did one of these come off? They need to be sealed.

 

Good Luck,

Jason

[Gio]

I connected up the PC in order to check the throttle posn and it reads from -1/0 closed to 100 fully open so I think the TPS is probably ok (if this is a godd enough test). Tick-over is approx 1000 rpm as indicated by the PC.

 

I don't know about the vent tubes that you refer to (?) but since the symptoms do resemble those of poor sync, I just checked this - see current measurements in cm of Hg vs engine speed in rpm with those obtained last time (in brackets) below (as measured at the inlet manifolds using a mercury gauge).

 

Engine speed LHS#1 RHS#2

 

tickover 15 (21) 16 (21)

2000 14 (18) 15 (18)

3000 24 (24) 26 (23)

4000 32 (30) 34 (30)

 

So where as last time I checked the sync, both cylinders were within 1cm across this range (spec from the manual is 7mbar which I calculate to be approx 0.5cm Hg) so no adjustments were made.

 

Now I have between 1 and 2 cm difference but have no idea if this is significant or not - can anyone advise. What is the recommended adjustment procedure for syncing?

 

Thanks again for all your help / patience

 

Gio

[docc]

Gio,

 

No question you are out of synch if the cylinders vary over 0.5 cm Hg.

 

It is best to bring the cylinders into synch 'off idle' and see that that they remain so as rpm rises. This is dine eith the idle air bypass screws closed. It is recommended to add a 'jam nut' to the thumb wheel to keep the linkage from changing.

 

Being certain the TPS is correct, then set idle at 1050+/- 50 and back out the idle screws 1/2 turn.

 

Frankly, I find the motor to idle more reliably at 3/4 turn and 1100+/-50rpm.

 

Gio, I could not understand your TPS measurement. I have seen millivolts (525 mV) and degrees opening (3.6 degrees).

 

I am thinking the 'vent tubes' Jason mentions are the hoses for the US spec vapor cannisters.

[Gio]

Thanks Doc.

 

The TPS "measurement" I gave was actually a quick check using the Power Commander s/w and observing the % throttle read-out. I checked when the map was installed (approx 12 months ago) that this read from 0 to 100 and so if the TPS had changed figured this would no longer be the case. In fact the readings were between -1 and 0 with the throttle closed and 100 with the throttle fully open (so my conclusion is that this has not changed - reasonable).

 

Is there a place you can easily measure the voltage from the TPS (other than using an in-liine connector with test points, or the old paper clip down the back of the connector routine) ?

 

So if I understand correctly :

 

1. close the bypass screws

2. back-out to between 1/2 and 3/4 turn to give 1050 to 1100 rpm

3. balance using the thumb-wheel (using a lock-nut to secure) ?

 

The manual isn't exactly over abundant with info on this procedure plus this is a first for me on a fuel-injected twin.

 

Yours with increasing anticipation,

 

Gio

[docc]

The manual says to :

 

Set the TPS

 

Adjust the idle (best done with the left idle screw, defeating the right completely)

 

Balance with the air bypass closed

 

Reset the idle

 

Warm up and check the CO

 

Reset the idle and check the balance

 

The manual actually says more than this, as you know. Every time you change one setting it affects the others, like a cat chasing its tail. As Dave Richardson says in "Guzziology" going over and over the procedure brings you closer and closer to the optimum.

 

You can "back probe" the ECU connector but straight pins work better than paper clips. Black/violet is positive and violet is negative.

 

I have found 525 mV (3.6 degrees open) at idle to be rather rich. This is why opening the air screws a bit more will often smooth out the unstable idle.

 

All of this , of course, IMHO after fussing, fiddling and fettling 24,000 miles.

[Gio]

I'm afraid I'm still confused....

When you refer to the "left idle screw" do you mean the horizontal adjuster that determines the end of the travel on the LHS?

 

Gio

 

(PS - I noted that both idle air-by-pass screws were at approx 5/8 out ie half-way between the manual and your recommendation of 3/4)

[al_roethlisberger]

...it sounds like we need a "How to set the idle, and basic tune-up" procedure posted in it's own thread, perhaps in the "How To" Forum. Ideally the thread would include photos so everyone knows which "screw" we are talking about at each step

 

I too am slightly confused as we may be interchanging terminology at times

 

Any volunteers?

 

al