96 CR250 Jetting


27 replies to this topic
  • BuenasNalgas

Posted August 01, 2011 - 11:03 AM

#1

Okay - Finally got the bike running for the 1st time since I moved back to Southern California from Colorado. The bike hasn't run since last October!

It's running strong - but the idle is very HIGH and turning the airscrew does nothing. I can be in first gear without giving it gas and it rolls down the street at about 1-2mph. Haven't touched the jetting on this thing once even since I bought it, so this is new to me.

I"m assuming it's idle is high due to jetting correct?

Is there anyone here in Southern California that can tell me what jets they are using?

Also it seems as if the pipe is getting VERY hot Very quick.

Thanks in advance.....

:smirk:

  • BDubb106

Posted August 01, 2011 - 11:10 AM

#2

Id start by cleaning the carb with a fine tooth comb before you start swapping brass... sounds like your lean due a gummed up or slighty clogged carb. Probably your pilot jet. Stock setting wouldnt cause your bike to run that poorly.

  • KcDavis

Posted August 01, 2011 - 11:29 AM

#3

The idle screw is the choke knob, so turn that first and see if it helps anything.

  • BuenasNalgas

Posted August 01, 2011 - 11:59 AM

#4

Id start by cleaning the carb with a fine tooth comb before you start swapping brass... sounds like your lean due a gummed up or slighty clogged carb. Probably your pilot jet. Stock setting wouldnt cause your bike to run that poorly.


Carb is clean as can be. I would imagine that going from riding at 5500-7500 feet to sea level i'm going to have to swap some brass. What I thought was going to happen was the complete opposite from what's going on now. I imagined it bogging out....

The idle screw is the choke knob, so turn that first and see if it helps anything.


Yes, I have had it turned all the way to the right till it's tight then have turned out counter clockwise and nothing changes. When I was in Colorado turning the airscrew did make adjustments in idle....i'm confused...

Keep in mind, i'm not much of a mechanic!

I appreciate the responses - any help is always appreciated!

  • CamP

Posted August 01, 2011 - 12:08 PM

#5

If someone jetted the bike for Colorado elevations, you are probably dangerously lean in California. If you are near sea level install a 172 main, 52 pilot, 2nd clip position on the needle and 1.5 turns out on the air screw.

  • KcDavis

Posted August 01, 2011 - 12:08 PM

#6

Definitely sounds like it is time for a pilot jet change.
What jets do you have in there now?

  • frdbtr

Posted August 01, 2011 - 12:09 PM

#7

Carb is clean as can be. I would imagine that going from riding at 5500-7500 feet to sea level i'm going to have to swap some brass. What I thought was going to happen was the complete opposite from what's going on now. I imagined it bogging out....



Yes, I have had it turned all the way to the right till it's tight then have turned out counter clockwise and nothing changes. When I was in Colorado turning the airscrew did make adjustments in idle....i'm confused...

Keep in mind, i'm not much of a mechanic!

I appreciate the responses - any help is always appreciated!


The airscrew is different then the idle knob on the top of the choke. Having said that, if you were jetted for 7500 feet above sea level, you should probably put your jetting back to stock and then go from there.

  • BuenasNalgas

Posted August 01, 2011 - 12:16 PM

#8

If someone jetted the bike for Colorado elevations, you are probably dangerously lean in California. If you are near sea level install a 172 main, 52 pilot, 2nd clip position on the needle and 1.5 turns out on the air screw.


yes it was jetted for Colorado Elevations, bike was most often run at Denver elevations which is 5500 ft...... What happens if it is run WAAAYYY to lean?

Definitely sounds like it is time for a pilot jet change.
What jets do you have in there now?


No clue on what jets, i've never once touched them. Bought the bike from a local guy it and it ran great......

The airscrew is different then the idle knob on the top of the choke. Having said that, if you were jetted for 7500 feet above sea level, you should probably put your jetting back to stock and then go from there.


Not sure what you mean by the airscrew being different then the knob on top of the choke, on my model bike that is the airscrew as well.

Sounds like it's time for me to learn about jetting and what not, i've never once touched the jetting. This is my first dirt bike and outside of it cosmetically looking like crap it has run strong for two seasons out in Colorado.

I do have a lot of maintence I want to do to the bike, but want to purchase another bike first so I'm not down for a couple months......

  • KcDavis

Posted August 01, 2011 - 12:19 PM

#9

Not sure what you mean by the airscrew being different then the knob on top of the choke, on my model bike that is the airscrew as well.


Actually the air screw is separate. The Choke doubles as the idle, but the air screw is on the side of the carb and works in conjunction with the pilot jet.

  • CamP

Posted August 01, 2011 - 12:35 PM

#10

yes it was jetted for Colorado Elevations, bike was most often run at Denver elevations which is 5500 ft...... What happens if it is run WAAAYYY to lean?


You end up with a fried engine and a $500 bill. Install the jetting I posted asap.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • BuenasNalgas

Posted August 01, 2011 - 12:51 PM

#11

You end up with a fried engine and a $500 bill. Install the jetting I posted asap.


Perfect, bike is now on it's stand awaiting proper pipe and jetting.....

Thanks for all the quick responses, i'm very new at this and am trying to do the right thing.

I think I might get the proper pipe and jetting worked out then maybe try and sell it so I can get a bit newer of one so I don't have a maintence issue on my hands. I really just want to ride and have fun, don't have a lot of time to be in the garage.....

  • BuenasNalgas

Posted August 03, 2011 - 11:52 AM

#12

Definitely sounds like it is time for a pilot jet change.
What jets do you have in there now?

It's got a 165 & I think 52 but the 52 was very faint so I'm not a hundred percent on that one.

I ordered a new 52 just to be sure as well as a 172 & 175. Should be here tomorrow so I'll post up some results of this swap in a couple days.

Thanks for all the help!!!!

  • BuenasNalgas

Posted August 05, 2011 - 12:52 PM

#13

installed 172 main ; 52 pilot ; clip in 2nd position ; air screw 1.25-1.5 turns out.

air screw doesn't seem to have any effect regardless of where it sits at???

bike still seems to be idle'ing very high. expansion chamber getting very hot very quick. anyone got any ideas.

should i slap a 175 main in?

thanks.

  • KcDavis

Posted August 05, 2011 - 01:10 PM

#14

How far did you turn the air screw in or out? The air screw works in conjunction with the pilot jet.

  • BuenasNalgas

Posted August 05, 2011 - 01:18 PM

#15

How far did you turn the air screw in or out? The air screw works in conjunction with the pilot jet.



1.25-1.5 turns out (counterclockwise)

BTW - Love the slogan in your signature!!!!!

  • KcDavis

Posted August 05, 2011 - 02:06 PM

#16

Did you try to turn the air screw any more or any less than what you set it to? Turn your air screw until it affects your idle. If you can get down to 1 turn or less from seated, then you need a bigger pilot, if you can get up to 3 turns out, you need a smaller one.


Oh, and thanks! I like that saying as well. I don't remember where I heard it, but I laughed my ass off! Ha ha

  • BuenasNalgas

Posted August 05, 2011 - 02:15 PM

#17

Did you try to turn the air screw any more or any less than what you set it to? Turn your air screw until it affects your idle. If you can get down to 1 turn or less from seated, then you need a bigger pilot, if you can get up to 3 turns out, you need a smaller one.


Oh, and thanks! I like that saying as well. I don't remember where I heard it, but I laughed my ass off! Ha ha



I've turned the airscrew all the in as well as all the way out and it doesn't make any difference either way.

I guess with that being said i should pony up the 175 PJ huh?



Yep - I just laughed out loud here in my office when I read that......I think others heard me :eek:

  • CamP

Posted August 05, 2011 - 02:25 PM

#18

I guess with that being said i should pony up the 175 PJ huh?


No, the main jet only handles wide open throttle. Check to make sure you have plenty of slack in the cable and that your idle knob is turned in sufficiently. If the cable and idle screw are okay, then it sounds like you are lean at idle, which is either pilot/needle jetting, which is unlikely, or an air leak.

On the PJ carb, turning the choke knob clockwise/in lowers the idle.

Edited by CamP, August 05, 2011 - 02:52 PM.


  • AXAxiom

Posted August 05, 2011 - 02:36 PM

#19

What elevation?, the 52 pj seems rich, and then you have a 172mj?
Sounds like a battle is going on in there
Doesn't it Sound contradictory?

  • BuenasNalgas

Posted August 05, 2011 - 02:51 PM

#20

No, the main only handles wide open throttle. Check to make sure you have plenty of slack in the cable and that your idle screw/knob is turned out sufficiently. If the cable and idle screw are okay, then it sounds like you are lean at idle, which is either pilot/needle jetting or an air leak.

On the PJ carb, turning the choke knob clockwise lowers the idle.


So don't go to a 175 main?

I will check the cable and turning the choke knob either way has no effect what so ever.

Never had a problem before in Colorado and the air screw did work when turned in or out.

What elevation?, the 52 pj seems rich, and then you have a 172mj?
Sounds like a battle is going on in there
Doesn't it Sound contradictory?


Sea Level in Southern California!

here is the suggested jetting from FMF

Main Jet 175 Pilot Jet 52 Needle R1369N Needle Position 3RD Power Jet N/A Air Screw 1.5 Fuel Screw N/A





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