Low idle stumble/cough

[richard100t]

Ok my bikes tb's are properly adjusted, the valves are to world spec, the plugs are clean & gapped. Thats what is right, & when the engine is cool the bike runs great. When the engine gets warmed up or hot after awhile the bike coughs at low rpm to idle speed. Sometimes it will stall in nuetral at a light when it hot also. It doesnt really do it after 4k rpm at all. I'm not sure if its a tps thing or something else Any advice on where to look & what to adjust?

[Dr Gil]

Ok my bikes tb's are properly adjusted, the valves are to world spec, the plugs are clean & gapped. Thats what is right, & when the engine is cool the bike runs great. When the engine gets warmed up or hot after awhile the bike coughs at low rpm to idle speed. Sometimes it will stall in nuetral at a light when it hot also. It doesnt really do it after 4k rpm at all. I'm not sure if its a tps thing or something else Any advice on where to look & what to adjust?

 

 

Hey! I've got that too!

 

I've always just considered it to be the "nature of the beast." It's air cooled and all. I've had mine take a big fart accelerating from a stop and into a corner...very disconcerting having the engine stop, even for a moment, while turning.

 

I'll be interested in what those more learned than myself in the ways of Guzzi's have to say.

[richard100t]

I know the v11 probably does this, but I'd like to tune as much of it out as I can.

[Ouiji Veck]

Still sounds like classic tight valves to me.

So where are you now 004/006?

Try 006/008 or even

Try RaceCo specs 008/010

The more I open 'em the happier it runs/starts

[docc]

As OV says, the 006/008 valve setting is the best first step . I always check valves as the first step in throttle body synch. Step two is to recheck the TPS. I find running more reliable with the TPS set higher in the range. Spec is 150mV +/- 15. I have found mine best at 160-165. Last go around I lowered it to 150 to save fuel. Didn't get better, bike ran a little worse.

 

At 42,000 miles I've tuned the Sport every 4000-5000. Two findings are worth highlighting. First the tach may be a bit optimistic. Mine is 300 rpm high. This means when I was setting my idle for what I thought was 1050 it was 750. Setting the idle to an indicated 1300rpm smooths things out noticably.

 

Second, the procedure calls for the air bypasss screws to be out 1/2turn. It's the last setting to make in the procedure. I know this may be heretical but running them out a full turn , especially when the ambient temperature is above 85 degrees F, really enhances the idle stability. It is not unusual ( or incorrect) for tuners to use the air bypass screws to balance the throttle bodies at idle and delete the right TB idle stop screw. Your results may improve by setting the right idle stop to 525 mV after having set the TPS to 160-165 at the full closed postition, then using the left idle stop screw to balance the TBs at idle. Finally, opening the Air Bypass screws up enough to indicate a correct idle ( again this may be 1300 on the bike's tach). Try the full turn.

[richard100t]

Ok I have a bit of a mea culpa here My tb's were a little off! That & the rear tire needed a little air too. I fixed both things & the bike runs much better now It still idles a little slow for my taste but that I can live with. I guess it was just the tb's were a little off & that made the bike cough a little.

[docc]

Is it pretty hot where you are? In the 90s here. I just did the whole sh'bang tune up on the Sport right up to the proper 1/2 turn on the air screws. I couldn't ride it 20 miles without idle aggravations. Back to the full turn.

 

Try it, if you don't like it it's the easiest thing to change in the whole set-up.

[richard100t]

Ooohh yes its plenty hot here today! It does run a little better when its cooler out. No surprise there. I think I've got it back to an ideal state of tune...for now lol

[zoltan c]

Mine is doing the exact same thing, since it has been hot around here, especially when you are on the hiway and than take the exit and come to a stop. The bike stalls if I don't catch it with the throttle. I haven't checked the valves, is the .008/.010 spec measured when cold or hot?

Also can someone post a pic of the air bypass screw, are there one on each throttle body or only one, which side? ( Yes I have had a few beer! So what? It is very hot today about 34C).

[docc]

Valves are checked cold. Some often say 'stone cold.'

 

I'll have to post a photo of the bypass screw when I get back. It's late now and I'm off to the South'n Spine Raid on the NC-TN border starting out early in the morning.

 

You can see the screws by looking up from the bottom of the throttle bodies. There is one on each side.

 

I've never let my valves run that loose. What says Pete and Greg on the valve spec?

[richard100t]

You should let your bike sit overnight before you check the valves. Metal expands when it gets hot & contracts as it cools.

[El_Gringo]

Hi all

I have been having this problem for so time and whilst browsing this morning I thought I'd add my 1p worth!

 

My bike would faulter around 3 to 3.5k, especialy turning at junctions and going round roundabouts. I thought my bike had been tinkered with before I bought it as it had race cans, K & N hi flows and the guy I bought it from told me it had a Power Commander. Like a fool, I didn't check it was still fitted-I guess he removed it a flogged it 'cos it weren't there! So with all the other guff fitted I suspected it wouldn't run as it should. After much procrastonation on my part i bit the bullet and set about a factory reset. I refitted the factory air box, set the valve gaps, bought a manometer and set up the TB's - followed the guides in these haloed pages - and now there in NO cough at all. I am on a completely standard set-up, perhaps not the most exciting, but it runs well!

[gstallons]

When You install aftermarket parts you MUST install PowerCommander and have it mapped for the bike. If you have a dealer/tuning shop around you have them do the mapping. I did and it took care of ALL my problems. When I took it to have it mapped the shop owner informed me to disconect the PowerCommander , if my problems went away, the problem would be in the mapping of the unit. I cannot over emphasize how much you need te assistance of a qualified person doing this for you...