[crock]

The new 2014 C5 (100% stock) has an idle speed that keeps getting higher as the bike get warmer. When fully warm it idles around 2000 rpm. I am aware of a few things that could theoretically cause this but is this a normal problem where new machines require an idle speed adjustment as they break in?

[no bs]

have your dealer adjust under warranty. way too high.

[Mr.Mazza]

Should be 1000rpm, at cold my bike is 500-700, warming to 1000ish, that is normal. To 2000 isnt

[Magoo]

have your dealer adjust under warranty. way too high.

This. Mine did the same around the 500km mark, just before first service. It's a simple fix.

[JVS]

You can adjust it yourself by turning the large brass screw on the throttle body clockwise (to reduce idle RPM). Refer to this video for more info - http://www.youtube.com/watch?v=w51XKoubABI

Make sure you adjust it when the bike is warm.

[Ducati Scotty]

The idle speed spec is usually inside the air cleaner housing.

You can loosen the rubber boot and ritate the throttle body outward to make the brass screw more accessible.  Only takes a few minutes.

Scott

[crock]

After adjusting the idle in the morning the bike would not start. I had to turn the idle speed back up to get the bike to start. After riding the bike for a few minutes I pulled over and readjusted the idle speed lower. I kept the bike running and rode around another 30 minutes. Evidently that was enough for the computer to 'learn" the new idle speed and the bike starts normally now, and idles normally. So lesson learned, adjust the idle speed after starting and ride around a while so the computer can get used to the new idle condition. Be prepared with a screwdriver to adjust the idle speed higher if the bike will not restart.

[gashousegorilla]

   Or just start the bike and get it up to operating temp... at around 80c or 175-180 at the head.   It should take a bit to get it there, depending on how cold it is out. And you may need to use the by-starter initially.   Then adjust the idle when it's hot.   If you loose your initial setting or you forget or didn't mark where you started ?  Lightly seat the screw all the way in .... clock wise. Then back it out ...counterclockwise, 3/4 of a turn.  And that will give you a good starting point to tweak the idle up or down... When hot.    If you do it cold, when the bike does warm up your idle will be too high or race.    Works for me......

[SteveThackery]

Evidently that was enough for the computer to 'learn" the new idle speed and the bike starts normally now, and idles normally. So lesson learned, adjust the idle speed after starting and ride around a while so the computer can get used to the new idle condition.

Crock: unfortunately the ECU on our Bullet doesn't work like that.  There is no "learning" capability: the ECU has no direct control over idle speed, and all it does when idling is adjust the duration of the fuel injection pulses (i.e. the mixture) until the O2 sensor indicates a stoichiometric ratio.  That's it - nothing more.  (By the way, it only does that when the engine is warm and has been running for at least 90 seconds.  Prior to that it runs off its internal map.  Again: the ECU in our bike has no ability to "learn" or update its own internal map.

You gave us a giant clue when you said your C5 is new.  The idle speed is usually way too fast when delivered, and keeps getting faster as you run it in.  If it's correct when hot, it usually won't idle when cold - presumably because the engine is still too tight.  This is completely normal and has lots of new owners puzzled and disappointed in equal measure (you will find my vociferous complaints to that effect elsewhere in this forum).

It will take a good thousand miles or more before you'll get a stable, reliable idle which is correct at most temperatures.  Until then, you'll be messing about with it every couple of days.  Whatever happens, don't come to any conclusions until it's got 1000 miles on the clock!  :-)  Everybody kept telling me that.  I didn't believe them, but I should have done.

Remember: the Bullet does not have any kind of idle stabilisation, nor automatic fast idle, built in, presumably to keep the costs down.

You say it won't start when cold if you have the hot idle speed set too low.  That's what the bi-starter is for - I was horrified to discover our sophisticated new electronic Bullets still have a manual fast idle for cold starting!  The bi-starter provides a temporary increase in idle speed (by bypassing the throttle valve).

Quite honestly, though, messing with the bi-starter is too fiddly.  Just get used to cracking the throttle open very slightly before operating the starter - that way it will always start, hot or cold.  This is never necessary on any modern Japanese bike, because all of them (that I know of) have some kind of motored throttle valve for cold running and idle stabilisation.  Our Bullets do not, sadly.

[crock]

Dang....just when I thought I was clever.....fooled again by making things too complicated!

[JoeSchmofo]

I was just wondering, now it has got colder does everyone elses Bullet run a bit lumpy until it's warmed up a little. Or do I need to take my bike back to the dealer?

[mattsz]

From new, mine never idled "lumpy", just too fast!  And, it hunted and surged only while in gear holding the clutch in ()

http://www.youtube.com/watch?v=n-b4gXWw5uc

Surges in gear, until I click it into neutral at 0:33 (you can hear it), then it just fast idles from there...

Took more than a full turn of the idle adjustment screw to bring it down, which solved that problem, but ever since then, it's been a second-kick-only starter when the engine's cold.  That video was 4000 miles ago, idle is fine now.  If only I could have that first-kick start back!

Follow GHG's suggestions for idle speed adjustment...

[SteveThackery]

From new, mine never idled "lumpy", just too fast!

Mine was never "lumpy" as such, either.  To me that sounds like a misfire, which definitely needs the dealer to look at it.

On the other hand, the idle speed on mine varied a great deal.  If you look at my posts elsewhere, you will see that I instrumented my Bullet to see why.  Basically, at idle the closed-loop mixture control causes the engine speed to vary up and down, especially when the idle speed is set too low (less than 1000rpm).

As the mileage has increased this variation is less severe (again, I assume it's because the engine is less tight and therefore needs less "effort" to keep it running).

I have shown that the idle mixture is rich (too rich) at any idle speed below about 1000rpm, presumably because the ECU regards anything less than 1000rpm to be "starting".  That is why the idle speed is specified as 1050rpm.

Unfortunately 1050rpm sounds ridiculously fast for this kind of low-revving engine.  Pre-electronic Bullets would idle at 750rpm very happily.  My mission is to find a way of running at a "traditional" idle speed without the excessive richening that normally accompanies it.

[SteveThackery]

Dang....just when I thought I was clever.....fooled again by making things too complicated!

Hey, crock, don't worry about that.  Like you I was disappointed to find out how unsophisticated the electronic management of the UCE engine is.  Much of what we know about the ECU is thanks to Ace (ace.cafe).  His company is working on a replacement ECU to accompany their tuning kits, and therefore they must have a pretty good insight into the existing ECU.  They have confirmed that the ECU is not a "learning" type, and neither can it be reprogrammed (remapped).  The replacement under development is reprogrammable, which is great.

[SteveThackery]

Sorry for three posts in a row!!

Crock: just one more thing to say.  Once it's well run in, you might want to experiment by disconnecting the O2 sensor (4-way connector under the front of the tank).  This forces the ECU to go into "open-loop" mode where it simply uses its internal map throughout the range.

Mine runs just great like that, and although the idle is still too rich, it doesn't keep varying up and down because - being open-loop - it isn't trying to correct the mixture all the time.

If I could find some way to avoid the excessive richness at idle, I'd probably run mine open-loop all the time (although it means the MIL lamp is permanently lit, sadly).