[Ridin Rick]

I have gone with the JD jetting kit and put in a 162 and the red needle at #4, and I am adding the boysen accelerator pump cover.

Do I move the low speed fuel screw to 1-3/4? I am seeing different settings in different messages...

any input would be appreciated.

[Asmith]

1) Warm up the engine to full operating temp.

2) Turn up your idle a few hundred RPM using the throttle stop screw (basically you want a fast idle). This will make it easier to hear small changes in RPM. Watch for overheating--pointing a big shop fan at your engine will help it from getting too hot during the fast idling. The whole procedure shouldn't take too long though.

Each time you change the screw setting 1/4 or 1/2 turn or so, wait about 5 seconds to let the idle speed normalize. It usually take the carb and engine a moment to react to the change.

3) Turn the fuel screw IN until the idle starts to drop and miss. The engine should die if you bottom out the screw. Your pilot jet is too big if it doesn't die when the screw is bottomed out--it should die before it gets that far in.

4) Then begin turning the fuel screw OUT. The idle should peak and become smooth. Keep going and look for the idle to begin to drop/miss again.

5) The goal is to find the setting that provides the highest and smoothest idle. If it's unclear exactly were that point is then set to the midpoint between step #3 and step #4. For example, if the idle starts to drop at 1 turn out and starts to drop at 2 1/2 turns out then 1 3/4 of a turn out should be the correct setting.

If the peak/smoothest RPM is reached somewhere between 1-2 1/2 turns then your pilot jet is correct (the 1-2 1/2 turns applies to most carb types). If you end up less than 1 turn out then your pilot jet is too big and you need a smaller one. If you end up more than 2 1/2 turns out or the fuel screw seems to make little difference as you continue turning it out than you need to go up (bigger) on your pilot jet.

To re-emphisize: If the idle never drops when you're turning the fuel screw in, you need a smaller pilot jet. If the idle never drops when you're turning the fuel screw out, you need a bigger pilot jet.

Typical fuel screw settings are in the 1 1/4 to 2 1/4 range.

6) Once you've got the fuel screw set, re-adjust your throttle stop screw (idle screw) to an appropriate idle speed.

And that's it! Your pilot circuit is now VERY close to ideal. From here you can experiment with how small adjustments affect low-end (i.e. small throttle openings) response and make adjustments for weather.

[[email protected]]

Nice post AS,and that's the way to do it.
A lot of these settings depend on where you ride. My 450X for example, even fully opened airbox,red JD needle, full exhaust system,HotCams Stage 2, was happiest with a 162 main,45 pilot, and 1 and 3/4ths out. Lots of othe guys in different areas run 165-170 mains,and up to 48 pilots and they run great.
Regardless, AS described the right way to set that fuel screw. Doug

[paul turner]

1) Warm up the engine to full operating temp.

2) Turn up your idle a few hundred RPM using the throttle stop screw (basically you want a fast idle). This will make it easier to hear small changes in RPM. Watch for overheating--pointing a big shop fan at your engine will help it from getting too hot during the fast idling. The whole procedure shouldn't take too long though.

Each time you change the screw setting 1/4 or 1/2 turn or so, wait about 5 seconds to let the idle speed normalize. It usually take the carb and engine a moment to react to the change.

3) Turn the fuel screw IN until the idle starts to drop and miss. The engine should die if you bottom out the screw. Your pilot jet is too big if it doesn't die when the screw is bottomed out--it should die before it gets that far in.

4) Then begin turning the fuel screw OUT. The idle should peak and become smooth. Keep going and look for the idle to begin to drop/miss again.

5) The goal is to find the setting that provides the highest and smoothest idle. If it's unclear exactly were that point is then set to the midpoint between step #3 and step #4. For example, if the idle starts to drop at 1 turn out and starts to drop at 2 1/2 turns out then 1 3/4 of a turn out should be the correct setting.

If the peak/smoothest RPM is reached somewhere between 1-2 1/2 turns then your pilot jet is correct (the 1-2 1/2 turns applies to most carb types). If you end up less than 1 turn out then your pilot jet is too big and you need a smaller one. If you end up more than 2 1/2 turns out or the fuel screw seems to make little difference as you continue turning it out than you need to go up (bigger) on your pilot jet.

To re-emphisize: If the idle never drops when you're turning the fuel screw in, you need a smaller pilot jet. If the idle never drops when you're turning the fuel screw out, you need a bigger pilot jet.

Typical fuel screw settings are in the 1 1/4 to 2 1/4 range.

6) Once you've got the fuel screw set, re-adjust your throttle stop screw (idle screw) to an appropriate idle speed.

And that's it! Your pilot circuit is now VERY close to ideal. From here you can experiment with how small adjustments affect low-end (i.e. small throttle openings) response and make adjustments for weather.

Agent Smoothie

could you repeat that please? i missed it the first time, silly me!

paul

[Eric Mac]

Will the setting of the fuel screw effect the color of the plug. I tore my bike down to lubricate all the suspension linkages and checked the valves. My plug looked pretty black, which would lead me to believe I need to lean it out a little. Either way, I will be following Agent Smiths directions for setting my fuel screw, but just wanted to hear if this will help the plug. Nice post Agent, even if you went through this on another post.

[Smash]

Will the setting of the fuel screw effect the color of the plug. I tore my bike down to lubricate all the suspension linkages and checked the valves. My plug looked pretty black, which would lead me to believe I need to lean it out a little. Either way, I will be following Agent Smiths directions for setting my fuel screw, but just wanted to hear if this will help the plug. Nice post Agent, even if you went through this on another post.

Yes if your rich anywhere it will change the color of the plug.

[[email protected]]

Yes if your rich anywhere it will change the color of the plug.

It sure will.
If you're not a rider who races or spends most of the time at or near wide open an often over looked part of that picture is the needle too.
For instance , the JD needle is actually a little leaner than the stock needle is in the second third of it's travel. Doug

[Bamm Bamm]

Nice post AS,and that's the way to do it.
A lot of these settings depend on where you ride. My 450X for example, even fully opened airbox,red JD needle, full exhaust system,HotCams Stage 2, was happiest with a 162 main,45 pilot, and 1 and 3/4ths out. Lots of othe guys in different areas run 165-170 mains,and up to 48 pilots and they run great.
Regardless, AS described the right way to set that fuel screw. Doug

Thats right where mine is and I love it,, I finally have it right.. Once you get it perfect you'll be sooo amazed with your bike.. Good luck.. With that guide from Agent you have it done in no time at all.

[[email protected]]

Once you get it perfect you'll be sooo amazed with your bike

Sweet ain't it Bamm Bamm ?
You know, this is what I'm talking about with that JD needle.
It's not as simple unfortunately to just make a lean bike richer everywhere and then it's great.
In the X's case, JD has the needle being LEANER in it's second 3rd of it's travel as it begins metering fuel, so it should feel really crisp, and maybe better than some I've ridden with either Honda needle that has the clip simply dropped.
Where do we ride most often anyway,us non-pro off-road guys ? It ain't on the fuel screw,and it's not on the main jet either unless we're in WFO country.Too rich or too lean, when we check our plugs after a good long while, will reveal plug coloring reflecting where the engine is the most. The needle can be very important.
That JD guy is pretty sharp. Ask Paul Turner, who was converted (SAVED ) when he received a red JD needle in the mail last year mysteriously Doug

[Skoot22]

1) Warm up the engine to full operating temp.

2) Turn up your idle a few hundred RPM using the throttle stop screw (basically you want a fast idle). This will make it easier to hear small changes in RPM. Watch for overheating--pointing a big shop fan at your engine will help it from getting too hot during the fast idling. The whole procedure shouldn't take too long though.

Each time you change the screw setting 1/4 or 1/2 turn or so, wait about 5 seconds to let the idle speed normalize. It usually take the carb and engine a moment to react to the change.

3) Turn the fuel screw IN until the idle starts to drop and miss. The engine should die if you bottom out the screw. Your pilot jet is too big if it doesn't die when the screw is bottomed out--it should die before it gets that far in.

4) Then begin turning the fuel screw OUT. The idle should peak and become smooth. Keep going and look for the idle to begin to drop/miss again.

5) The goal is to find the setting that provides the highest and smoothest idle. If it's unclear exactly were that point is then set to the midpoint between step #3 and step #4. For example, if the idle starts to drop at 1 turn out and starts to drop at 2 1/2 turns out then 1 3/4 of a turn out should be the correct setting.

If the peak/smoothest RPM is reached somewhere between 1-2 1/2 turns then your pilot jet is correct (the 1-2 1/2 turns applies to most carb types). If you end up less than 1 turn out then your pilot jet is too big and you need a smaller one. If you end up more than 2 1/2 turns out or the fuel screw seems to make little difference as you continue turning it out than you need to go up (bigger) on your pilot jet.

To re-emphisize: If the idle never drops when you're turning the fuel screw in, you need a smaller pilot jet. If the idle never drops when you're turning the fuel screw out, you need a bigger pilot jet.

Typical fuel screw settings are in the 1 1/4 to 2 1/4 range.

6) Once you've got the fuel screw set, re-adjust your throttle stop screw (idle screw) to an appropriate idle speed.

And that's it! Your pilot circuit is now VERY close to ideal. From here you can experiment with how small adjustments affect low-end (i.e. small throttle openings) response and make adjustments for weather.

This post should be a sticky

[Bamm Bamm]

Yeah it's amazing the power you find when something runs right.. Most of my riding is trails and hillclimbing and I like to jump on the MX track and lap a few people for the fun of it..


This should definately be a sticky.. Ok I gotta load up the bike=) My buddies on his way out and we're going to Carnegie