2006 Crf250r carb problems

[Moto Man26]

Hey everyone! I have a 2006 crf250r and I'm having some problems with a terrible idle and low end bog... The bike doesn't take it when I snap the throttle too quickly... It just bogs badly... But if I give it throttle slowly, that is fine... I have stock jetting in the carb : Main jet=172

Pilot jet=40

Needle- 3rd position from top

Starter Jet=68

Air Screw=1.5 turns out

I told my self that it's probably lean on the pilot jet. So I bought a #42 pilot jet. But after talking to others, some say that I need to play with my AP(accelerator pump) , and leave the pilot stock. I didn't close it up yet in case I really need to do something with my AP... Please help!! Thanks!

[William1]

What size leak jet is in it? Many run a #60 down to a #40.

Did you do the oring mod?

Once the above is done, you can adjust the ap timing 1/2 turn CCW at a time (keep good notes, testing after each adjustment (riding, not reving on the stand) until the bog barely is perceptible.

And the others are right, the pilot jet is for idle (as is the fuel screw)

[Moto Man26]

Alright here is an update.... I left the #42 pilot jet in, and I did the AP mod, and I put a new spark plug.... I then decided to start it up. It fired up in 1 kick And idled well.... But then it just stalled.... And wouldn't start anymore... I took out the plug and It was wet.... So I'm now guessing that my problem is my pilot jet is too big, and that I should leave my pilot jet stock (#40).... Please Help!! P.S. I also gave my pilot screw 2 turns out instead of 1 1/2.... Could my pilot screw be the problem of the too rich symptom on start up??

[Moto Man26]

Alright I took apart my carb, and put back the stock Pilot jet(#40) and set the screw at 1 1/2 turns(stock)... I also checked the leak jet and it's a #55... What do you think?? That sound ok...??

[William1]

Wet plug... hmmmm if it was only running a few seconds, I could see it getting wet.

Here is the deal. You started with a 40 pilot and a fuel screw half way open. You enlarged teh ilot jet arbitraialy and opened the fuel screw more. Not sensible.

In any case, this is the correct procedure for selection a pilot jet and setting the fuel screw. Being your bike is four years old, please use a brand new (not cleaned )stock sized pilot.

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

Once you have the idle right and the fuel screw set as above, them and only then, go and play with the AP.

[William1]

Alright I took apart my carb, and put back the stock Pilot jet(#40) and set the screw at 1 1/2 turns(stock)... I also checked the leak jet and it's a #55... What do you think?? That sound ok...??

Leak jet should be fine. Do the fuel screw adjustment exactly as outlined above.

[Moto Man26]

Alright I'm getting pretty tired of taking the bike apart every time... I put the carb back on with all the stock settings. And kicked it over like 10-15 times before it fired up (cold start).... After getting it to start, I warmed it up , and then it started to idle ,but the idle was high, so I turned it down a bit to a proper speed, and it would idle for a few secs and start to drop and want to die, so i would rev it up, and it would idle high again, it would only come down after a few secs or I would have to unsrew the idle..... I Can't get a proper idle:banghead: Also the bike would not want to start hot at all:banghead: I would have to push start it , and it would start right up immediately.... I'm completely lost!! I'm started to think that my valves are badly adjusted maybe...

[Live 2 Ride]

Knowing your valves are in spec is a good place to start.

Also kinda sounds like you may have and air leak somewhere or you need a new exhaust header copper gasket.

Do you seal the carb boots and everything correctly ?

[Moto Man26]

I checked for air leaks, and there are none... What does your copper gasket have to do???

[Moto Man26]

Also I think I forgot to mention, that the carb is all stock besides the AP mod...

[William1]

Did you have the slide out of the carb?

[Moto Man26]

I left the slide in the carb, I just cleaned it out while it was in the carb, I only took off the top little cover to inspect the needle....

[William1]

Two more possibilities. A worn needle jet emulsion tube or a float set wrong.

[carp killer]

taggage

[Moto Man26]

alright I'll check those out....

[Moto Man26]

Also, by the way, how do you check the float level on these carbs?? Do you just set the carb upside down like any other carb and let the float sit lightly on the needle valve.....???

[William1]

Pretty much. Do not let the float depress the pin, just have it touching. I hold the carb at an angle to facilitate this.

[Moto Man26]

Yeah I will check my float because, it has been changed but I think the level is wrong....

[highmarker]

If the fuel pukes out the overflow when the bike is leaned `45deg then stops when you slowly pick it back up, the float level is pretty darn close. Not an exact science but close enough for a quick check.

I'd leave the 42 in it as honda did in the later years,, they seem to cold start better. You must tune the fuel screw as William outlined, an extended fuel screw makes the job so much easier. Also remember evrytime you twist the throttle your suirting raw fuel in, so how many twists you give it before you kick it is part of the starting routine, too many and you will wet the plug.

[highmarker]

If the fuel pukes out the overflow when the bike is leaned `45deg then stops when you slowly pick it back up, the float level is pretty darn close. Not an exact science but close enough for a quick check.

I'd leave the 42 in it as honda did in the later years,, they seem to cold start better. You must tune the fuel screw as William outlined, an extended fuel screw makes the job so much easier. Also remember everytime you twist the throttle your squirting raw fuel in, so how many twists you give it before you kick it is part of the starting routine, too many and you will wet the plug.