2011 S40 2000 miles.  Tachometer,  Raptor petcock, idle mixture screw 1 turn out, washer mod, 50 ft above sea level.  My first winter with this bike.  I had some growing pains with getting the bike running right this summer, but over the last few months, really thought I had it dialed in.  Keeping in mind I live in Texas and it doesn't get cold compared to other parts of the world, I did notice during summer and fall I never needed choke, and to the contrary if I tried using even a little choke the bike would run roughly.  No problem right?!

Fast forward to yesterday, run bike in garage for a little while to keep gas fresh.  It needed the first little notch of choke just to get started (15 seconds) before idling good with no choke.  After running 10 minutes, I notice bike is idling at 1600rpm.  Idle was set during the summer at 1200.

My questions are:

1. Is this normal?
2. Does this mean I'm too rich? Seems unlikely given how notoriously lean these bikes run.
3. Should I just adjust idle from summer to winter? I always understood a vehicle properly tuned should run the same regardless of air temp.

Thanks everyone.

Well......why don't you adjust the idle mixture screw and find out if the bike is too rich or not?

https://www.youtube.com/watch?v=zm5mB3R8Ucw


It is unusual that an engine runs faster when it is cold out.  The air is denser and wants a bit more fuel as a result....and the fuel tends to condense on the cold intake tract and not stay mixed with the air until the engine is warm.  Generally folks have to bump the idle speed up a bit for cold weather running.

This is a primitive engine with a carb.....so it has no ability to adjust mixture and rpm like your fuel injected car does.  You will have to make the adjustments if the engine isn't running well.

Running the engine stationary for 10 minutes .....I wouldn't do that to my bike.  It is better to get the engine warm on a ride if you are going to leave fuel in it all winter.

I understand the mixture screw procedure and did so this summer, hence my confusion.  Perhaps I only think I did it right.

What is the setting the screw came with from factory? anybody know?

I'm at work right now and can't play with bike right now.  Was just looking for some idea bouncing.  You inadvertently answered my question.  If bikes running higher rpm with colder denser air than warm air...should mean running at least a little rich.  

I mention the bike ran 10 minutes just to illustrate the bike had been running, but definately not at full operating temperature.  I do ride during winter.  but this week has been particularly cold, onlly reason I didn't take it out.

Winter,summer,didn't matter, well,how MUCH mita changed,but the pattern was the same,,,

Fire up, idle is too low, adjust,ride, lower idle during the first 15 or so minutes,,, crude design,I loved that about it,AND they built the idle adjust so a hand could grab and adjust while riding..
I should say I don't remember that being an issue before I put the cam in and the Supertrap on.. But ohhh the backfire issue,, which,looking back,was
Likely leaking header issues.
So,WHY did you get a higher idle? Dang if I can even guess...