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post #1 of 36 (permalink) Old 03-27-2010, 11:51 PM Thread Starter
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help! fast idle at sstart up

since i put on cobra speedster slashdowns, there is a fast idle at start and the bike takes a very long time to idle down. has anyone had this problem befor? and what can i do about it? just ordered s&s intake and PC V. any help would be greatly appreciated
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post #2 of 36 (permalink) Old 03-28-2010, 12:34 AM
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Originally Posted by chefskeeter View Post
since i put on cobra speedster slashdowns, there is a fast idle at start and the bike takes a very long time to idle down. has anyone had this problem befor? and what can i do about it? just ordered s&s intake and PC V. any help would be greatly appreciated
OK one more time same answer.

I was told by the dealer about the fast idle when i picked up the bike, 3 miles on it stock. Man it some time shoots up to 1800 RPM, really annoying, scared the crap out of a mech at an independent shop , the S&S should have a position for the sensor to plug into, the BAK did, if you get rid of it there is no choke and it will run like crap until it warms up a bit, MOM says do not ride for up to 2 min on cold days after starting (RIGHT).

OH and mine also fast idles every time it is started even on a hot day, but calms down quickly.

Very irritating with pipes that set of car alarms but what can you do, would love to hear any suggestions that would work. I guess you could play with the idle screw and kick it up and then back down, but i am leary about turning it down to much because of oil flow, oil pump does not pump enough pressure below 900 RPMs and i have not installed a tach yet (note to self new item on MODS list )

Good luck and keep the shiny bits in the air.

John
"I am a modern cowboy, on a steel horse I ride"
09 VN900 Classic
Big 3 +++++
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post #3 of 36 (permalink) Old 03-28-2010, 05:33 PM
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Mine does the exact same thing. Very annoying. It's as if the computer does not read the temp sensor right away. I wish someone would come up with a solution for this.
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post #4 of 36 (permalink) Old 03-30-2010, 12:49 AM
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I was glancing through the service manual and here is what it says

•Start the engine and warm it up thoroughly.
○At first the engine will run fast to decrease warm up time
(fast idle).
○Gradually the fast idle will lower to a certain RPM automatically.

So isnt this normal?
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post #5 of 36 (permalink) Old 03-30-2010, 03:42 PM
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yes it is normal.

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post #6 of 36 (permalink) Old 03-30-2010, 09:54 PM
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OK one more time same answer.

I was told by the dealer about the fast idle when i picked up the bike, 3 miles on it stock. Man it some time shoots up to 1800 RPM, really annoying, scared the crap out of a mech at an independent shop , the S&S should have a position for the sensor to plug into, the BAK did, if you get rid of it there is no choke and it will run like crap until it warms up a bit, MOM says do not ride for up to 2 min on cold days after starting (RIGHT).

OH and mine also fast idles every time it is started even on a hot day, but calms down quickly.

Very irritating with pipes that set of car alarms but what can you do, would love to hear any suggestions that would work. I guess you could play with the idle screw and kick it up and then back down, but i am leary about turning it down to much because of oil flow, oil pump does not pump enough pressure below 900 RPMs and i have not installed a tach yet (note to self new item on MODS list )

Good luck and keep the shiny bits in the air.
Bytehead, which sensor actually modulates the idle speed when the bike is first started? Any idea how the idle is increased? More air?
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post #7 of 36 (permalink) Old 03-30-2010, 10:27 PM
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Quote:
Originally Posted by krravi View Post
I was glancing through the service manual and here is what it says

•Start the engine and warm it up thoroughly.
○At first the engine will run fast to decrease warm up time
(fast idle).
○Gradually the fast idle will lower to a certain RPM automatically.

So isnt this normal?
I agree with this being normal when the engine is cold. But after riding for a few hours in 80 deg weather, stop to fill up with gas, start bike and its reving like a raped ape. Its like using the choke on my carbed Roadstar when the motor is fully warmed up.

This is what doesn't make sense to me.
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post #8 of 36 (permalink) Old 03-30-2010, 10:30 PM
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Quote:
Originally Posted by krravi View Post
I was glancing through the service manual and here is what it says

•Start the engine and warm it up thoroughly.
○At first the engine will run fast to decrease warm up time
(fast idle).
○Gradually the fast idle will lower to a certain RPM automatically.

So isnt this normal?
Yes the fast idle on the initial start up is normal. What I was referring to in my case, is if I shut the bike down for 10 minutes after it is warmed up and start it back up it will idle fast for about 20 seconds. I would think that since the engine is still warm at this point there should be no need for an increase in idle speed.
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post #9 of 36 (permalink) Old 03-30-2010, 10:39 PM
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Originally Posted by f4kev View Post
Yes the fast idle on the initial start up is normal. What I was referring to in my case, is if I shut the bike down for 10 minutes after it is warmed up and start it back up it will idle fast for about 20 seconds. I would think that since the engine is still warm at this point there should be no need for an increase in idle speed.
Exactly the point I was trying to make!

Is there something the Kawi engineers considered important we're missing?
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post #10 of 36 (permalink) Old 03-31-2010, 01:14 AM
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Bytehead, which sensor actually modulates the idle speed when the bike is first started? Any idea how the idle is increased? More air?
Disclaimer: "Not a kawi rep or engineer just ask a lot of questions"

My limited understanding of the situation, is the little black plug that is in the air intake box (breather) is the cold air sensor, this is the little bugger that sets the idle to fast for up to two minutes when air temp is below 50. Then it is shut down when the engine temp sensor, signals the engine is warmed up the "choke" fast idle is shut off. The start routine in the ECU is Preset to start in fast idle, probably by the starter energizing, service manual is not specific, but i ask a lot of questions .

If you have ever started it, shut it off oops, and restarted it again the fast idle always kicks in whether it is 100 or 50, absolutely a pain in the ***(for the kiddies). I get lots of comments that start out "WTF that thing is idling way to fast" and then when it just slows down on its own.

The speed is increased the same way an old manual choke works, increases the fuel going to the engine, FI ya know, but instead of creating higher suction with a choke valve, just kicks the fuel flow up a touch. You can see the richness if you look at the pipes (not stock) and smell the rich fuel mix. And if you hold the throttle lightly you can feel the throttle move just a small amount.

From the service manual page 2-15 "○At first the engine will run fast to decrease warm up time (fast idle)"

So yup cannot do a thing about it, trying MAY damage the ECU, may not but why take the chance.

You have two options, like I did "get used to it, and get over it", or park it and walk (not an option, to much fun to ride).

Sorry to confirm the bad news but "HEY SCREW IT, LETS RIDE "

Oh and never assume,(insert an - after last s and u and think about it) that anything, that anyone else does, is logical or makes sense, someone must have thought this was a good idea, did not happen by mistake.

On a better news topic I (I.E. another poster steered me in the right direction) found a great solution for the ever present, left turn stuck in ****, problem but that is another post, ask if interested

Hope this helps, ride safe and keep the shiny bits in the air.

John
"I am a modern cowboy, on a steel horse I ride"
09 VN900 Classic
Big 3 +++++
Double Darkside

Last edited by Bytehead; 03-31-2010 at 01:28 AM. Reason: late and eyes not good.
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