KDXRIDER.NET

After riding - I park my bike and want to run it at idle until it starves itself of fuel and dies (after switching fuel petcock to 'OFF').

How many minutes should it take for engine to die after petcock is switched to 'OFF'?

And, I am curious how many turns out you have your fuel-air mixture screw - who run 40:1 oil fuel mix ratio?

Manual says 1.5 +/- 0.25.

Byte

Re: 'How many minutes...'

Varies. More than 10 seconds, less than five minutes.

Probably.

....considering your petcock to actually BE off (which it probably isn't 'cuz the KDX petcock is usually real fussy about where 'off' is).


I've never thought that whole process (running the engine out of fuel) to be a reasonable thing to do. Lots of folks do it. Running a 2T to the point of fuel (and lubrication) starvation? OK. It's your bike.

'I've been doing that for over 20 years!!!..never had a problem!!' <anyone> says.

OK. It's your bike.

If you want the bowl dry..loosen the drain plug on the bottom. Or..simply lean the bike over after you shut the fuel off.


It's not a fuel-air mixture screw. That is important to know and understand.

It's simply an air screw. Some carbs DO have fuel screws. They are adjusted differently and as the name implies, perform completely different functions from an air screw.


You set your air screw to such a position as to get the best throttle response from a quick twist from off-idle to 1/2 or so throttle position.

I recall that process (air screw tuning) to have been covered in an earlier post where you asked the same question.......

In direct answer to your question, 'How many turns...' Mine is generally around 2 3/4, adjusted +/- over the course of temperature changes of the riding day.


...which has absolutely nothing to do with your bike. A bored/plated/modified carb (RB-Designs) isn't tuned 'just like' an OEM carb.

...but you did ask.

Cheers!

Good info canyncarvr, thanks.. Do you drain the bowl on your RB carb?

bronco95tgp wrote:Good info canyncarvr, thanks.. Do you drain the bowl on your RB carb?

Probably less 'info' and more 'opinion'.

I don't drain the bowl on my carb for transport or short term storage..and the bike's never really had a 'long term' storage.

Pretty much the only time I use that drain plug is for a main jet change.

Oh yea some people would say its your opinion not concrete info. I tend to lean towards using your opinions as info but thats just my opinion. I'm with you on the storage period.

Thanks boys.

I only heared a kawasaski dealer suggest i do it to prevent plug fouling and thought I might float the idea on here...I have not yet actually purposely run the bike to fuel starvation levels. I won't do this now. Good advice!

THanks for clarifying the nomenclature with their specific differences of mixture screw and air screw.

I am assuming this mixture screw is also referred to as the "idle screw" as the manual refers to this screw as these different names in different sections of the manual.


Do u turn/adjust the air screw with engine still running?

Byte

Anybody here ever foul a plug on your KDX? <crickets>

Yes... you can adjust while running.... as I often do... several times a ride even!

I drain the fuel out of the carb via the plug if it's gonna sit more than a week. Damn ethanol.

Re: 'I am assuming this mixture screw is also referred to as the "idle screw"'

That would be an incorrect assumption.

The mixture screw is NOT the idle screw for the same reason the idle screw is not the mixture screw.

Two different screws.

Air screw is brass, idle screw is black nylon.

Please tell me you knew that already.


Re: '...the manual refers to this screw as these different names..'

Where in the manual does it do that?


Re: 'I only heared a kawasaski dealer suggest i do it to prevent plug fouling...'

Not inconceivable. Some 2T oils (read: castor) don't like to stay mixed. They 'drop out' of solution...especially in cold weather. If you had a mix of that sort..and it separated in the bowl you could get that oil sucked into the carb. That would foul a plug quite handily..being oil soaked.

That 'drop out' isn't nearly as much of a problem with newer oils.

Re: 'Do u turn/adjust the air screw with engine still running?.

Yes. While riding, even.

I've never liked turning the fuel off and running it dry. Reason being just as the fuel is running out the engine will begin to race. The reason for that race is more air less fuel......less fuel means less oil and as the engine runs completely out of fuel that means your running a dry piston & rings in a dry cylinder.

I'll turn my petcock off and time how long until the engine dies tomorrow.
My family had a boat shop for years and unplugging the fuel plug and idling the engines until the carbs are empty was standard procedure. We never saw any problems done to the engines from this ever.

-Erik

Hmmm.... I just put Sta-bil in the tank and fog the carb until it dies on my boat.

Thansk boys. Good to see difference of opinion/information here..

Re: "The mixture screw is NOT the idle screw for the same reason the idle screw is not the mixture screw.... Two different screws."

Kawasaki refer (online manual) to this black nylon mixture screw as an "idle screw" under "Periodic Maintenance - Engine Idle Speed"

And, I am confident many other bike riders also refer to this mixture screw as the idle screw.

Yes Canyncrv - I did know that the black mixture nylon screw is the idle screw...... and I sense another empty 'google' flavoured discussion coming on....

Byte

There is no mixture screw on a KDX carb. Only idle and air.

..... hence Kawasaki are incorrect.



.... from KDX online manual (Engine troubleshooting) ......

Byte

It is a misprint. Kawasaki didn't write that... Cyclepedia wrote that.

I would tell them.

Do you see any mixture screw? (Click it if you can't read it)

OK boy and girls,

There are two types of idle "OR" low speed circuits in the basic motorcycle carb.

And I call all of them "Mixture Screws" too. As in both types of carbs, they are adjusting the air/fuel mixture or ratio in the low speed circuit.

The PWK carb in question uses a fixed low speed jet (you can change these to different sizes) and a screw to add or subtract air into the circuit to fine tune the circuit. SO it does control the fuel mixture in the low speed circuit, "Mixture Screw".

Other types of carbs use a fixed and non adjustable air bleed (usually a drilled hole) into the low speed mixture and the fuel is introduced via a pilot jet and a fine tuning screw to allow more or less fuel into the low speed circuit and that is how you fine tune the low speed circuit. SO it does control the fuel mixture, "Mixture Screw".

Usually if the Mixture Screw is in the back of the carb body (near the air horn) it is a air adjustment. Clockwise will richen the mixture and counter clockwise will lean the mixture.

If the Mixture Screw is up on the top or bottom side of the carb body near the intake boot, it is a fuel mixture. Clockwise will lean the mixture and counter clockwise will richen the mixture.

There are some carbs that use both a air mixture adjusting screw and a fuel mixture screw together on the same carb. These carbs were on some older 4 cylinder 4 stroke street bike engines.

Never the less, I call any screw that will adjust the air/fuel mixture on the low speed circuit a "Mixture Screw"

Ron

Ps. Please note all carbs and situations have been addressed in the above message. I'm only trying to give the basics.

'..black mixture nylon screw..'





I didn't see that one covered!



Maybe that's what they call 'em 'down there'. It's easy to get confused when you're upside down all the time.........

Indawoods wrote:There is no mixture screw on a KDX carb. Only idle and air.

Gotta problem with that Wibs? I stand by that statement.

I can't help it if people don't call things what they are.... they can call it whatever they want.