Idle dropping at stops/lights

[thebronze]

Time for my annual post dogging the Guzzi fuel system!  Ok this year I have the stock air box back on and it ran decent most of the winter.  Now its getting hot outside and after 10 minutes the bike is fully warm, it starts missing a little between 3-4k rpm.  I think we are lean again.  When I had the air pods in place the surging in this range was horrible and unsafe at times.  It was diagnosed by a lean condition caused by the air pods.   Now its much better with the airbox, just a little miss.  The real problem is when i'm pulling up to a stop light or stop sign.  The rpm will drop down to 5-600 rpm and try to kill the motor.  If I blip the throttle a bit it recovers and will usually idle around 1400.  It has died on me a few times in this situation but always starts back up.  I have the idle set to 1400, a little high but i'm trying to keep it from dying..  TPS is set, carbs are synched, had my mechanic do an 02 analysis during tune up.  I'm still thinking the stock fuel map is to blame and i'm trying to reach Todd at Guzzitech for a reflash.   But i'm wondering if these two items might factor in to my problems at stops signs/lights.

 

1.  Air bleed screws, i'm at 3/4 a turn out.  Any further out and it gets leaner.  What would running them in do to the idle speed?

2.  Throttle cable is loose at the intake assembly loop.  The only way I can see to tighten is at the twist grip and the cable adjuster is all the way out.  Maybe the cable is stretched and in need of replacement...

 

Love to hear any thoughts, ideas, or curses.  

 

Thanks,

Toby

2002 vll lemans

[Tom M]

Hi Toby,

I don't think the stock map is causing your problems.  I've had the stop sign stalling issue in the past and fixed it by by doing the basic V11 tuneup.  It sounds like you had a tuneup except you didn't mention a valve lash check.  When they get too tight and the bike gets hot it can lead to erratic idle and stalling after pushing the bike hard.  The manual says .004" intake/.006 exhaust but most here use the .006" intake/ .008 exhaust.  If you have to adjust them you will likely need to rebalance the throttle bodies.

[thebronze]

Hi Toby,

I don't think the stock map is causing your problems.  I've had the stop sign stalling issue in the past and fixed it by by doing the basic V11 tuneup.  It sounds like you had a tuneup except you didn't mention a valve lash check.  When they get too tight and the bike gets hot it can lead to erratic idle and stalling after pushing the bike hard.  The manual says .004" intake/.006 exhaust but most here use the .006" intake/ .008 exhaust.  If you have to adjust them you will likely need to rebalance the throttle bodies.

 

Tom, I adjusted those last year but its probably time to check again.  They might be too tight.  PO had them set 10-12 thou or so....  I found some ugly spark plugs while I was in there.  I dont think the gap was set.  It was about 1mm.  Proly straight out of the box.  I put new plugs in at .7mm per the manual.  I will check the valve lash tonight.

[docc]

Good advice on the "gentle" valve lash and rebalance the throttle bodies. I have always found more stable idle in hot ambient temperatures with the air bleed screws at one full turn. I know that would be theoretically leaner, but I've tried them everywhere and always end up back at one full turn.

 

Those are the simplest things worth trying.

 

There is a mod to the head temp sensor that is somewhat controversial, but worked for my Sport in the 90-95˚F (40˚C) temps here in the sunny/muggy USA south.

[thebronze]

I found the right side exhaust to be a little snug.  The manual must be joking with the listed spec. Its better now but still trips a little at stops.  Its almost like a car when the ac compressor clicks on or off.  I might try the raceco spec next.

[docc]

Open your air screws - can't hurt. If you don't like it, put 'em back. One synch method calls to synch the throttle bodies at over 2,000 rpm ("off idle") and use the air screws to balance at idle.

 

What are using for air filter? How old are the plugs?

[thebronze]

Good ole Docc, your always around.  Ok, lets see, stock airbox and filter are back on and it runs 100x better than pods.  Brand new plugs gapped at .7mm.  Air screws are 3/4 turn out from fully in.  Seems like the more I open the air screws the more lean it gets in the mid range.  Tonights ride was the best its ever been.  It didnt really miss between 3-4k and I tried to make it.  Its just clumsy at stop signs.  Its time for the yearly throttle body synch up and maybe check the TPS to see if it wandered.

[docc]

The air screws really shouldn't affect the mixture materially past idle. Idle is what they are all about. Try the full turn, you can always put it back.

 

Repeating the full Tune-Up would be good medicine at this point. Every time you do it, the parameters get closer and closer.

 

Once upon a time, my Sport haunted me with the Nasty Hiccup. That's a link to the last post in a year long thread that I found a handful of "contributors."

 

I recall removing the air bleed screws and cleaning them along with the holes they fit in.

 

Not sure how hot it gets where you are in the USA, but two things have made a big difference for me: fuel without ethanol and the low mass engine temperature sensor holder.

 

EDIT: Oh yeah, when Andy York zeroed my CO in the ECU: major difference in idle stability. My V11 was delivered with the CO at - (minus) 27.

[thebronze]

Docc, its definitely worth a try.  I agree,  need to get the idle zero'd.  I'll try to find the usb cable and use the new software.  I dont have much time.  I'm trying to rebuilt my Moto Morini 350 right now and get the Motobi 250 dialed in.  I think there are 2 other bikes that need work as well.

[moto fugazzi]

Is there a leak in the cap or hose that you used on the "nipple" where you connect the carb sync tool? 

Ken

[AndyH]

Raceco clearances and ensuring no leaks in the exhaust system joints fixed this one for me

[Tom M]

It sounds like you're getting there Toby.  Like Doc I have my air bleeds set at one turn out and my idle trim is set to zero.  I sync' my TBs at about 1800rpm.  My bike runs great with a consistent idle and no coughs or hiccups, but I do have a PCIII.

 

This is the basic V11 tuneup instructions that I use (aka the Micha Method):

 

Step one - Set your valves to world settings (.15mm/.006" intake, .2mm/.008" exhaust)
Step two - Set your air bleed screws to open 1 full turn
Step three - Synch throttle bodies at just off idle (around 1800 rpm)
Step four - Set idle to 1100 using left idle screw adjuster only
Step five - Set TPS to 3.6 degrees (530mV)
Step six - Ensure idle trim is set to zero. This requires an AXEONE dealer tool, VDST software, or GuzziDiag.

[thebronze]

Not sure how, but 1 turn out on the air screws made the idle stumble even worse. 

[docc]

FWIW, the factory air screw setting is 1/2 turn out. It just never worked for me. But worth trying.

 

I noticed Pete Roper's post regarding the Griso to be certain you high-speed balance the throttle bodies with the air screws closed lest you munt the idle. He didn't say it quite like that, but we all know that his faithful assistant, Colin, does all his posting for him.

 

Assuming you have a balancing tool, it is another simple thing to try.

 

Has your TPS been set for the fully closed position (no linkage, no high-idle contact, no idle screw contact) as the initial starting point?

[thebronze]

Docc, I went through all that last year. I think I need to synch the TB's after adjusting the valve lash.    I might dial it back to 1/2 turn out and try an easy fix.  I havent bought a carb synch tool just yet.