Hesitation/sputtering on cold take-offs

My 2011 always sputters and hesitates for about the first 10 seconds of acceleration when starting out cold. It behaves like it's not getting enough fuel. After these few seconds of reluctance the motor grabs hold firmly and runs flawlessly the rest of the time. I'm running the Beetle map for the stock can, which has greatly improved my fuel economy and generally smoothed out all the other kinks in running and acceleration. When I loaded the new map, I didn't change the CO trim at all because the idle is spot-on at around 1200. Is it possible that adjusting the CO trim would remedy this issue without screwing up the idle? The bike now has about 5500 miles and I've had no other issues with its running, except for a very brief engine clatter that has occurred a few times under very hard acceleration (the sort you apply whilst smoking a Harley that challenged you at a stoplight). Any ideas out there?

Sounds like a fuel-engine-temp issue if it's gone after it gets warmer. A CO trim adjustment is worth a try. Try +1 or +2 and see if it improves.

The engine clatter could be "pinging" under load, indicating either lean mixture of too much ignition advance.

It's not the ignition. A TB imbalance can cause pinging too, but in this case I suspect it's a tad lean. Hence the CO trim adjustment.

Thanks fellas. Temperature seems to be the key, as this stumble only happens when the engine is stone cold. I'll bump the CO trim and see if that does it.

Changed the CO trim to +1, then +2. Stumble is still there. Any other ideas?

Is it always after a start? Regardless of how hot the engine is?

It's only after starts when the engine is stone cold. It doesn't do it when it's even slightly warm. After those few seconds of stumbling, it runs perfectly.

Just jumping into left field here, but how healthy is your battery? reason I ask is if the voltage is slightly low and you affect a start from cold, the system voltage will take some seconds to bring the voltage up - this affects the injectors' ability to give a full squirt until this voltage is normalised, which it will be after running for a bit. Obviously after been ridden for a while the engine is warm and voltage is better...

A stretch I know, but I've had it happen on mine - turned out to be dirty earth and battery connections - go figure.

Right. I know what to tweak. I'll build you a new map.

Thanks Mark!!

It almost brings a tear to my eye to see this happening, I tried to get help like this with an add on device that shan't be named ( don't mention the war ) only to be fed cold shoulder.
We have a few people to be thankful for here guys, I couldn't Buy this kind of help 2 years ago, Enjoy

Ron, having the people here who know what they are doing, offer help and deliver in a most outstanding way, enables the rest of us to enjoy our bikes properly. Hats off to the inner sanctum on GRiSOGhetto.

And Alan dropped over last night with his laptop and Beetle maps + stock map and happily bounces from screen to screen comparing pulse widths/temp tables & TP% etc. blah blah blah.

Actually it is educational and informative, but Al has got his head around this tech stuff quicker than I can play a game of Spider Solitaire. But it is all starting to appear like basic XL spread sheet stuff, and that I can handle. One day ...................

I have recently found the same issue, if I dont let it warm up a bit and I shift to second gear its like is gets starved for fuel. If I stop and let it warm up a bit (at the stoplight one block from my house) the issue is gone.
Did a map fix rectify the issue? Not sure which version of Marks map I have but I got it back in january.

Did it do this when you first loaded the map, or has it only just started doing it?

Honestly not totally sure as I have been riding the NTX lately, normally I let the bike warm up a bit while I put on gloves etc and have not noticed any issue but last couple of days I have GRiSO to work and not letting it warm up, just start n go and notice it.

Check your air bleed screws Peaceman. Mine were both open (a tuning no-no) and that was the culprit. Try closing them both. If that doesn't help, open one and leave the other closed. If that doesn't help, reverse it, open the closed one and close the open one. If it's like mine, one of these combos will cure the stumble.

Rather than that very hit and miss method I'd suggest doing it properly with guages and Guzzidiag.

Also. Is this a flat tappet bike? If so it is probably worth checking your valve clearances to see if they have changed appreciably.

Pete

I have been chasing a problem with a dip between 2 and 3K. Mark gave me some modified maps that  helped fill in the dip but I had the difficult running when cold, it would almost stall sometimes. I bumped the CO to +5 and the cold running cleared up. I still have a slight flat spot between 2 to 3K when warm. I am going to check the valves next. Also, taking up the throttle cable slack, and balancing the throttle bodies helped quite a bit.
Mark has been enormously helpful, Thank You Sir!

I changed a bit in the warmup map, the corner with low temps and on the left in my tunerpro. (the highest values.) No need to change anything else. Leave Co, it changes everything warm and cold.

Hw cold is it when you call it cold? under 15 celcius?

2011 SE (green) 9800kms. I did valves TBS etc this spring before getting on the road with the new map. I recall the valves were a bit snug but I can check em again its easy to do. Its tuned very well and runs very smooth and powerfull other than this gargle in the morning. By cold I am saying 8-12c in the morning. Its now 27 here and I just rode for 30mins and it runs excellent. The only thing I have not done is play with the CO trim much. In fact I think it may be at zero.

hmm. CO was at 6 now at 2 (idle less lumpy) bike is getting even better. Would this have any effect on the cold running?

Yes.

Awesome, I will tinker with that more prudently. Thank you.