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unusually low idle?


potatobroxd
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I've recently installed a delkevic carbon exhaust on my Vulcan 650 and sounds WAYYYYY better than stock (or any other 650 parallel twin).


Although, I've noticed the idle being lower than the manual's guideline (although im not sure if it was due to the exhaust change as i cant remember the rpm prior to the change)


Warmed up RPM = 1000 exact

Warmed up RPM according to the Owner's Manual = 1250-1350


I dont know if this may cause low oil pressure to the engine?

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Oil pressure won't be a problem - does it give you a solid idle without excessive vibration? I'm never keen on low idle where everything gets shaken about.

 

It's all normal, just sounds like the idle could be a bit higher

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Turn the idle up!

 

Its a fuel injected bike, how should I do this?

 

Have you got the manual for it? The online version simply says to adjust the idle screw. If it's got a manual idle adjustment it's just a case of adjusting it by small increments.

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Turn the idle up!

 

Its a fuel injected bike, how should I do this?

 

You will have a little nob poking out (ooo err) from around the location of the throttle bodies normally on the right hand side of the bike


Just give it a little turn and when I say little I mean little!

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Turn the idle up!

 

Its a fuel injected bike, how should I do this?

 

Have you got the manual for it? The online version simply says to adjust the idle screw. If it's got a manual idle adjustment it's just a case of adjusting it by small increments.

 

Thanks, I found it! More details next thread

 

Turn the idle up!

 

Its a fuel injected bike, how should I do this?

 

You will have a little nob poking out (ooo err) from around the location of the throttle bodies normally on the right hand side of the bike


Just give it a little turn and when I say little I mean little!

 

I just popped back im the store and tuns out the dealership changed the idle speed using this nob to compensate for the lean condition of the exhaust? Seems very confusing to me, I'll explain the details in a new topic

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I'm no expert, but I would guess the new pipe let's the engine "breathe" better, allowing more air to flow through. The manufacturer would have set up the fueling to match the air flow of the original exhaust.

So now, assuming your ecu doesn't know there's increased so flow, the bike will be running lean ( not enough fuel for the amount of air), which increases cylinder temperatures and will eventually cause damage to the engine.

Ideally the ECU needs to be remapped or have a power commander fitted.

Sounds to me like the dealer has adjusted the idle so that fueling is more or less correct at tickover, but won't be right with the throttle open.


There are cleverer people on here who know more about this stuff than me, so don't take this as gospel

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Altering the idle control will have no affect on the fuel mixture!


All it does is crack the butterflies open a little more

 

Agreed. My bad.

My original thought was a bit arsebackwards.... reducing the airflow makes no difference if the ECU is getting engine speed from the crank sensor and pumping in fuel according to a preset map :/

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Altering the idle control will have no affect on the fuel mixture!


All it does is crack the butterflies open a little more

 

Agreed. My bad.

My original thought was a bit arsebackwards.... reducing the airflow makes no difference if the ECU is getting engine speed from the crank sensor and pumping in fuel according to a preset map :/

 

You also have to think about the throttle position sensor too as that has an affect somewhere down the line


So closing the idle down the ecu knows you have adjusted it etc


The idle screw basically opens the throttle a little bit more


A lot of people confuse idle screw to mixture screws on carbs! An idle mixture screw alters just that the idle mixture but has no affect on the rest but on injection bikes you have no idle mixture screw to play with

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You could try starting it from stone cold and leaving it to idle for around 10 minutes, this can allow the ECU to (attempt to) set itself up for a new exhaust/rotten original exhaust/blocked air filter etc. and may provide a bit of a fix for your problem.

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