Hey, I have a 2002 honda cr250r and having troubles with idling the bike. I start it and the bike goes in high idle, I have been trying to adjust the carb. So i turned it off and did the following. Ive set the air screw 1 3/4 turns counter clockwise from lightly seated position as the manual told me. Now im having trouble setting the fuel screw cause the manual doesnt say where to set it. Presently i have the fuel screw turned all the way inside the carb(clockwise) my dad says the all the way out(counter clockwise) and go from there. What is a good position for the fuel screw to be set at so the bike doesnt go into high idle?
Adjusting the carb
- Thread starter LivinLife
- Start date
shane Arnold
Member
- Jan 3, 2009
- 6
- 0
make sure the case or cyl. isnt sucking up any air other than through the carb. If theres a air leak some where the bike will idle and rev high
Your bike doesn't have a fuel screw. There's an air screw and an idle screw. The idle screw is at the base of the slide tower on the carb. It uses a wedge effect to lift the slide. If you turned it in all the way that would explain the high idle. The best way to get it roughed in is to loosen the clamps in the air boots and turn the carb so you can see the slide. Back the screw out till the slide bottoms out then turn it in until it lifts up a little. The air screw should be close enough to get it running where you have it.
- Thread starter
- #4
Thanks JOE. Thats what i meant to say when i said fuel screw.
I got the part about loosening the clamps that secure the carb to the air boots and rotating the carb towards me, but do not understand "turn the carb so you can see the slide. Back the screw out till the slide bottoms out then turn it in until it lifts up a little". Where is the slide inside the carb im guessing. Will I have to take the throttle cable off and the top set of the carb in order to see it? Or can i do it without taking it off?
I got the part about loosening the clamps that secure the carb to the air boots and rotating the carb towards me, but do not understand "turn the carb so you can see the slide. Back the screw out till the slide bottoms out then turn it in until it lifts up a little". Where is the slide inside the carb im guessing. Will I have to take the throttle cable off and the top set of the carb in order to see it? Or can i do it without taking it off?
rmc_olderthandirt
~SPONSOR~
- Apr 18, 2006
- 1,533
- 8
First, make sure that you have properly identified which is the idle "speed" and which is the idle "mixture" adjustment.
The best way to positively identify the idle speed screw is to take it all the way out and look at the tip. If it is pointy, it is the mixture needle. If it is blunt, it is the idle speed. The idle speed may have a lock nut on it that you will need to loosen in order to turn it easily, and then tighten to have it stay in that spot.
The next thing you should do is to make sure that the throttle cable is not too tight and holding the throttle open. If you twist the throttle open, then slowly let it return you should feel the tension come off the twist grip while it still has a tiny bit of rotation left. If there is spring tension all the way down to the twist grip stop then you need more slack in the cable.
If you don't have enough slack in the cable it might be because the cable is not routed properly and it is pulling the jacket out of the carburetor or twist grip a small amount. With the bike running you should be able to flex and move the throttle cable without it changing the engine RPM.
Many of the throttle cables have a mid-cable adjustment for the jacket length. This will be a little metal fitting where one piece threads into the other. Loosen the lock nut, thread the fitting together a bit more, tighten the lock nut again. This will make the jacket shorter, which will loosen the cable inside.
If you have plenty of cable slack then the throttle slide should come down and rest against the blunt end of the idle speed screw. If you just back the screw out the slide should drop and the idle RPM drop with it. If the slide won't reliably drop then it is an indication that the carburetor is either damaged or just so dirty that the slide won't move freely.
Rod
The best way to positively identify the idle speed screw is to take it all the way out and look at the tip. If it is pointy, it is the mixture needle. If it is blunt, it is the idle speed. The idle speed may have a lock nut on it that you will need to loosen in order to turn it easily, and then tighten to have it stay in that spot.
The next thing you should do is to make sure that the throttle cable is not too tight and holding the throttle open. If you twist the throttle open, then slowly let it return you should feel the tension come off the twist grip while it still has a tiny bit of rotation left. If there is spring tension all the way down to the twist grip stop then you need more slack in the cable.
If you don't have enough slack in the cable it might be because the cable is not routed properly and it is pulling the jacket out of the carburetor or twist grip a small amount. With the bike running you should be able to flex and move the throttle cable without it changing the engine RPM.
Many of the throttle cables have a mid-cable adjustment for the jacket length. This will be a little metal fitting where one piece threads into the other. Loosen the lock nut, thread the fitting together a bit more, tighten the lock nut again. This will make the jacket shorter, which will loosen the cable inside.
If you have plenty of cable slack then the throttle slide should come down and rest against the blunt end of the idle speed screw. If you just back the screw out the slide should drop and the idle RPM drop with it. If the slide won't reliably drop then it is an indication that the carburetor is either damaged or just so dirty that the slide won't move freely.
Rod
If you can see any kinks or the inner metal covering, replace the cable. It will only cause problems otherwise. Cable routing is very important, double check it! Turning your handlebars and the rpm goes up can lead to an accident quickly. Back that idle screw out till the slide slams closed. Start it and adjust inward till you hit the rpm you want. Its got to be warmed up to do this. Then you get to start jetting, post #4:http://www.dirtrider.net/forums3/showthread.php?t=159938&highlight=spanky's+jetting+guide
