Other Bringing back a Crf230l

J

johnrunner

So didn't get to the carb today. Took off the side cover to get a look at it and after I saw all those gizmos and wires hooked up to it I got fluttered and said i'll wait on it :lol: Not having the manual for it gets me second guessing myself a lot. I downloaded the OEM manual but I couldn't find anything about the carb in it :noidea:. I also shed some more weight on the scooter. Took of the pass. peg's and hardware as well as the side reflectors. I noticed that the side reflectors were hooked by a long one piece crossarm that ran underneath the tank area and connected to the frame. It also was connected to the side shrouds. So when I took off the entire assembly, it left the bottom corners of the shrouds unsecured so they shake easy. Looks like I'm going to cut the down the crossarm so I only leave what is need to secure the shrouds and still benefit by removing the excess weight of the crossarm metal, reflectors and hardware.

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So I have a question. When I removed the passenger peg's and hardware, I noticed that they did not clamp on to the frame but rather be bolted in through a hold in the frame simply held in by a pin. By removing the hardware, does it weaken in the frame? Should I leave the bolt inside the hold with the pin and just take off the pegs? Or does it not matter as since the bolt wasn't in there super tight and simply pulled out. Here's a pic of it.

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J

johnrunner

So finally got around to cleaning the carb. I noticed it wasn't to dirt in there but the pilot jet was dirty so I used a thin wire brush to push through the holes and clean it out. Now I don't have that bog off take off as I did before and the throttle response feels much better :banana: But I still noticed that the idle is kind of weird, as it hangs on after I give it rev. Why does this happen? Also did not see any adjustment areas to move the needle around. Am I missing something here?

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J

johnrunner

That's what i was thinking jax, as I had it happen on my YZ, and I had to replace the air boot that connected to the carb. I removed the air flap piece that funnels air into the air box, thus allowing a ton more air in, so you think the excess amount of air and not being able to tune the jetting is causing it? :confused: I might try installing the air piece in again and seeing what happens.
 
jackson409

jackson409

I know when I did the air box mod on my sons KLX it let in too much air and I had to end up change the jets to allow for the throttle up bog but your issue is just the idle is not droping fast enough. I don't know, It could be caused by too much air not enough fuel. I would see if replacing the flap fixes it and if does you just need to go up on the main mabey one size. I am not expert though. Lets see what Biggy-D says :smirk:
 
SRAD97750

SRAD97750

Moderator
Staff member
What you describe is a "hanging idle." Typically caused by a cracked airboot downstream of the carburetor, which makes it impossible to fix by adjusting the carburetor. But since yours is nice and clean, I am fairly positive the airbox modification is the culprit.

OK. Since we're "going there," I'll whip it out all over you...

There are multiple 'circuits' (passages) in the carburetor that are metered by jets. Each circuit reacts differently at different throttle positions. Each circuit is adjustable, some in multiple ways.
For this instance,
With the throttle closed, the idle circuit (sometimes called slow jet) provides fuel through a jet and downstream of the slide. Typically much smaller than the other jets, and has a screw adjustment on the side/bottom of the carb. This is called the idle mixture screw. It can be adjusted 'on the fly.' The jet is also interchangable and sizes come in tiny increments. Typically $3-$6 each.

So, first and most importantly, you need to get the bike completely warmed up. So that you can't touch the cylinder with your hand. If it's not warmed up completely, you are wasting your time.
Second, let it come to idle. Turn the idle speed screw so the rpms increase to a high idle. The following is performed at a high idle.
Next, turn the idle mixture screw slowly counter-clockwise until the engine speed slows. (Richening)
Now, Turn it clockwise until the idle speed peaks. (Leaning) Stop there, and back it out 1/8 of a turn. (Should be slightly rich for cooling)
Lastly, set your idle speed screw back down to a realistic idle speed.

This should solve your hanging idle cause by an airbox mod. This means you will also increase the power potential of the carburetor as a whole!
To read more about this subject I strongly suggest this website. It is an excellent source on carburetor theory.
http://www.iwt.com.au/mikunicarb.htm
DISCLAIMER: 2 stroke carburetors typically have idle mixture screws that control air intake. 4 stroke carburetors use a screw that controls fuel.


Now, on to your needle adjustment, which I recommend over changing the main jet.
Take a photo of your needle and slide separated, i'll explain how to adjust it. It's not like a regular carburetor slide.

:wiggle:-BIG DAN
 
J

johnrunner

No that's as good as it gets, sorry. I remember that piece though, it was a little white plastic piece that basically turned into the rubber and stayed in place by three teeth. And the needle didnt have any other slot it could of went it.
 
josmoloco

josmoloco

I had a hanging idle on my xr650r stock, uncorked. After i pulled out the restrictors and rejetted, the issue was gone. It can be caused by a lean idle circuit.
 
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