Running poorly when cold

[fjdog]

So my 2016 bike has about 3,400 miles on it now.  I have not done any engine, ecu, or exhaust modifications.  Lately, it has been running poorly when it is cold.  Sometimes it coughs, sputters, drops power, or one time it seem to backfire.  Once it has warmed up, it runs great.  I did not have this problem before.  No check engine light.  I don't think it is the fuel, it has happened with 3 different tanks of gas.
 
Has anyone else experienced this?
Any suggestions on what might be the cause?
 
Thanks in advance.

[betoney]

When you say running poorly when it is cold, do you mean outside temperature or the engine temperature? Do you start it and take off immediately when the engine is cold?

[fjdog]

Thanks for the replies.
 
betony, I mean when you just start it and take off riding. Not ambient temperature.
 
piotrek, I can check this again. I did do it at the initial service interval as directed. One intake was slightly off and the adjustment took it to the limit. The job of checking the sync was terrible for the ability to access the vacuum port on the leftmost intake, if I remember correctly. Also taking the entire top structures off is a pain. I will mention that it idles just fine, the problem occurs when I put the bike under mild to moderate acceleration.
 
Any other suggestions out there?

[betoney]

Thanks for the replies. 
betony, I mean when you just start it and take off riding. Not ambient temperature.

How does it run when its properly warmed up? 
 
I always start the engine before getting suited up.  By the time I have my jacket, ear plugs, helmet and gloves on, the engine has warmed up and the screen is displaying a true temperature instead of "Lo".
 
If it runs rough for the first minute or two and then runs great when its up to operating temperature, maybe consider letting it warm up for a few minutes.
 

[josh]

I recommend you warm up any internal combustion engine to operating temperature before you use it hard.

[skipperT]

Thanks for the replies. 
betony, I mean when you just start it and take off riding. Not ambient temperature.
 
piotrek, I can check this again. I did do it at the initial service interval as directed. One intake was slightly off and the adjustment took it to the limit. The job of checking the sync was terrible for the ability to access the vacuum port on the leftmost intake, if I remember correctly. Also taking the entire top structures off is a pain. I will mention that it idles just fine, the problem occurs when I put the bike under mild to moderate acceleration.
 
Any other suggestions out there?

 
Something sounds off to me about how you performed the sync.
 
“One tb was off and adjustment took it to the limit”.
 
No. That’s probably your issue. If you remember which throttle body you adjusted, wind it back in as many turns as you remember taking it out and see if it runs better.
 
Usually TB sync requires an adjustment with the air screw of 1/8 to 1/2 turn either in or out, to bring them in line with the rest of the TB’s.
 
If you had to move it more than that, I would question your sync gauge or your method.
 
Sorry to be this blunt, but check your work first. ESP if the symptoms started soon after you performed the work. Or take it to a shop if you don’t want to deal with it again.
 
-Skip

[fjdog]

Skip, I will mention that the bike ran great for thousands of miles after I did the sync, cold or warmed up. It only recently started running poorly. As a matter of checking my work, I rotated the gauge inputs between tb's to see if I got the same readings and I did. I also checked the gauge by connecting all inputs to make certain each read the same values. If I had just worked on the bike in some way you are correct that it could be the cause.

[skipperT]

FJ, that’s good to hear. Thanks for the info.
 
But I’m still troubled by you having to wind out an air screw A LOT to bring the throttle bodys in sync.
 
What could have theoretically happened is there was some gunk in the airbleed passage, or on the air screw and you adjusted the air screws to balance.
 
Fast-forward many miles later, that gunk may have worked its way out, and you now have an unbalanced situation where one airscrew is wound out too far, causing a hard start due to imbalance and an air leak that the YCCT is trying to compensate for based on idle speed and o2 feedback.
 
It’s just a theory, and I could be wrong - but it’s worth checking. Especially because no Yamaha I’ve ever synched has airscrews out that far on just one airscrew in relationship to the other 2 (or 1 or 3 depending on the model), unless something else was wrong on the bike.
 
Check the spark plugs also. They may be fouled or carboned-up from short run cycles without proper warm up.
 
My $.02.
 
-S