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2003 WRF 250 with erratic idle - Mr Burned Please help!

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The WRF 250 would not idle at all. After taking it apart to clean it up, I put it back together and it will now idle, but very erraticly. Either it revs too high or too low. I have the mixture screw at 1 1/2.

The carb is jetted as follow (it has a T-4 and I think the jetting job was done quite well):

Main Jet: 180RD

Pilot Jet: 40

Starter Jet: 72

Pilot Air Jet: 75

There are two problems:

1- The idle adjuster screw is bent and therefore it gives a resistance in the knob until it turns all of a sudden and pushes too much on the pulley

2- When I removed the mixture screw, there were no washers to be found.

I wonder if the washers could not be inside the carb, but I guess not. I pushed some air and some carb cleaner, I looked with a light, nothing came out.

Not the first time I disassemble that type of carb, I know for a fact the washers come down and never get stuck in there.

Isn't it unlikely that the carb washers are pushed in into the carb? Frankly I don't know for sure if the kid did not take it apart before me.

I am going to buy a Zipty-type mixture screw so that we can adjust a lot more easily, I guess I should really buy the new washers, am I correct?

Could it be possible the bike was working fine without them?

Also how many turns do you suggest on the mixture screw? That too might have been played with.

I rode the bike otherwise and besides the idling issue, it is jetted fine.

If I reduce the idle with the adjuster know, it seems to be ok but it ends up dying in a big hickup. If I open the throttle, same thing.

What am I missing here?

Thanks in advance!!!

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there should be a spring,washer and oring ont he fuel screw.they need to be there.

did you have the slide out of the carb?

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No I did not remove the slide out of there. I made sure it was sliding fine.

Is it possible for the rubber and the metal washers to be inside of the carb? I would hate to leave them in there. So far a visual inspection has shown nothing.

The previous owner had the carb "cleaned" by a shop prior to selling it to us (I guess he had it garaged for too long).

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Yes the slide plate is the square end down.

How could the oring and washed be stuck in there? Have you seen that happen?

First time I removed the screw, nothing came out, I had the carb facing down.

How can I make sure these parts are in there.

I will try and see if I can find anything in the hole with a paper clip.

Thanks for the help!

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They could be stuck up in there just because they are a fairly low tolerance fit and they could get turned a little sideways and get stuck. However, if you can't see them in there then they are most likely gone. You will need to buy the whole fuel screw assembly from a dealer in order to get the right ones again. They will not fit through the orifice in the carb, so if you can't see them in the threaded hole in the carb then they are gone. Hope this helps.

Josh

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If they were not in there in the first place is it possible for the bike to idle correctly anyway?

I will get an MSR mixture screw from a dealership today and order the oring and washer from a place like Sudco, they retail the pieces separately apparently, but you need to get at least $25 of product.

Should I order some jets at the same time and what would you recommend?

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Not a bad idea to have a few jets laying around, depending on where you are going to ride. If you change elevation by more than 2-3 thousand feet then you will have a call to do some adjusting with your jets. You also may run into situations where weather will require jetting changes. I would recommend that you get a new idle adjust screw if yours is bent. You shouldn't have any trouble getting 25 dollars worth of stuff. Especially if you are ordering the fuel screw too. Hope this helps.

Josh

P.S. Mains and Pilots will be most important. I would say you will want 2 or 3 steps smaller that what you are running in both jets. You may also want to get 1 or 2 larger just so you can play around with it and really get a feel for what happens with the different settings.

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Ok, I could never find the o-ring nor the washer, I guess the previous "tuner" decided to not replace these parts after taking the mixture screw out.

I will order new parts.

I bought an MSR screw and it helped fix the idle issue.

But the main issue is that the bike does not get back to idle right away, now. When I open the throttle and release it, the bike will rev, but will keep revving for a while until it decides to get back into idle.

This has nothing to do with the action on the throttle pullie, as when I have the engine off, I can help it hit the stop screw when I release the throttle stop. The action of the throttle is free.

It just keeps revving and pulling for about 2 more seconds. Pulling unless you clutch out. Gotta be careful!!!

What seems to be the issue here?

Thanks in advance!

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Yes, it is a square end.

I did not have any issue before the bike slept in the garage for 6 months.

What would cause the bike to retain open throttle when I release said throttle?

Never seen that before but then never had to deal with a Keihin FCR before.

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Hanging idle is normally caused by a lean pilot circuit. This means that you may need to adjust you fuel screw, increase pilot size, and possibly adjust your needle clip position. Move the clip down on the needle to richen the mixture. Start with the screw and go from there to the pilot and then to the needle if you need to. I am suggesting this course of action because you already told us that you cleaned the carb thoroughly. Hope this helps.

Josh

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lean fuel screw setting or plugged pilot jet.

I have the fuel screw at 1 3/4 out right now, do not think it is necessarily the issue.

The idle adjuster was a pain to set due to the screw being bent and it resisting then moving too much all of a sudden. I guess the kid took a bizarre slow fall on the side in the rock (probably stalled it in a technical single track hill then, well you know).

I will experiment first with a bigger pilot jet, then.

At least now it idles. But it is really finnicky to find, and sometimes the bike would hickup and die, the carb moving back and forth.

Choking effect.

Bike is ridable but requires more clutch and braking action, I would call it ridable but dangerous to ride.

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Just a note to throw in here if the rest of this doesn't work. My husband 03 WR had an erratic idle problem too. After much touble shooting it came down to the fuel pump accelerator being bad. Once that thing was change it's been a pleasure to ride.

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Just a note to throw in here if the rest of this doesn't work. My husband 03 WR had an erratic idle problem too. After much touble shooting it came down to the fuel pump accelerator being bad. Once that thing was change it's been a pleasure to ride.

How much did this cost? What part would I need? Is it just the diaphragm?

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I have the fuel screw at 1 3/4 out right now, do not think it is necessarily the issue.

The idle adjuster was a pain to set due to the screw being bent and it resisting then moving too much all of a sudden. I guess the kid took a bizarre slow fall on the side in the rock (probably stalled it in a technical single track hill then, well you know).

I will experiment first with a bigger pilot jet, then.

At least now it idles. But it is really finnicky to find, and sometimes the bike would hickup and die, the carb moving back and forth.

Choking effect.

Bike is ridable but requires more clutch and braking action, I would call it ridable but dangerous to ride.

You have been given the same suggestion on the fuel screw and pilot jets several times in two different threads now. You come on here asking for suggestions from those with more experience than you and you refuse to try them. You are ready to drop money on a new accelerator pump when you may very well find that turning the fuel screw out another turn or two will fix your problem and idicate that your pilot jet is too small. I don't understand your logic I guess. If you don't believe that the fuel screw is the problem, maybe you should try to prove it while you are waiting for the answer you want to here? :thumbsup:

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