rough idle/ unless choke is pulled a few mm


14 replies to this topic
  • opiejrt15

Posted November 18, 2012 - 12:04 PM

#1

bout a 03 wr 450 to convert to a sm it is now dual sport but i am having issues with the carb took it apart cleaned it didnt help so i went up on my idle jet from a 42 to a 48 and main jet was 165 to a 170 then to a 175 have adjusted needle to every possible setting with all three jets i am still havin back fire on decel hot start is blocked off new choke and orings are good and intact on carb takes a min to start when it does it will not idle unless i ride for 10 min at stop signs or red lights it either dies or i have to hold throttle to keep up rpms have sprayed boots with cleaner to check for cracks it is in time and stock exhaust pea shooter removed gytr tip in grey wire mod air filter stock yet im still gettin cherry red exhaust and at idle it clears up when i pull choke just a little while riding it lunges unless i pull the choke out i should be running rich but still seems like im way lean any suggestions

  • Bandit9

Posted November 18, 2012 - 01:12 PM

#2

Got to be pilot. I had mine apart a few times chasing the same thing, and I'll be damned if the pilot wasn't clogged each time. This is after cleaning it each time before. Bikes that sit for a while with Ethenol in the tank stored in a shed or something, like used bikes that we buy, tend to have a gunked up carb/tank that take a few detailed cleanings.

Also are you running a fuel filter b/t tank and carb? Your tank could have crud in it, thus clogging the pilot after each cleaning.

  • Pooley

Posted November 19, 2012 - 04:53 AM

#3

Punctuation is your friend, by the way. That was very difficult to read.

You never mentioned adjusting your fuel screw at all. If it is all the way in, it will probably be lean at idle regardless of the pilot jet size. Count how many turns out the fuel screw is set and record it, then start adjusting it. I would set the fuel screw at about 1-1.5 turns out to start and adjust from there. Also, make sure the fuel screw is installed properly, in the proper order. It should be O-ring, washer, spring, screw.

Edited by Pooley, November 19, 2012 - 04:58 AM.


  • Pooley

Posted November 19, 2012 - 05:01 AM

#4

Check this out too, it sounds rather familiar: http://www.thumperta...__fromsearch__1

  • travertt

Posted November 19, 2012 - 09:18 AM

#5

Punctuation is your friend, by the way. That was very difficult to read.


YES!!...without it you are hard to understand...and I'm sure you are smarter than no punctuation makes you appear.

  • opiejrt15

Posted November 24, 2012 - 06:53 AM

#6

yes i have adjusted fuel screw, for a while it was not doin anything when i turned it. moved my needle and got it to running on pilot jet. last night i flipped the rubber valve on left side of carb. i also took a piece of inner tube and blocked off hole on acv valve it helped. i am still popping on decel and bad bog on initial twist

  • Leardriver

Posted November 24, 2012 - 07:26 AM

#7

A new pilot jet is around $6. It is very tough to clean the old ones completely.

Save yourself some aggravation and screw a new one in there, and set your fuel screw to 2.0 turns out, and see how it runs.

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  • William1

Posted November 24, 2012 - 02:49 PM

#8

Go back to a stock pilot. As Leardriver states, pony up and put in a new one.

Fuel Screw/Pilot Jet
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 1,850 rpm, but go by the spec in your manual.

  • opiejrt15

Posted November 24, 2012 - 05:55 PM

#9

even with the 48 pilot still is running rough. have went to stock setting have the manual put everythng to stock settings it just ran worse. have adjusted fuel air screw to try to help clear up idle. once i turned mixture screw in all the way it died backed it out 1/4 turn. no matter what i do it seems like it is gettin to much air. so far when i take carb apart none of my jets have been clogged, have had carbs apart every other day for two weeks.

Edited by opiejrt15, November 24, 2012 - 06:12 PM.


  • MANIAC998

Posted November 25, 2012 - 03:57 AM

#10

Is your hotstart partially engaged? If there's not enough freeplay in the cable, then perhaps your hotstart is partially open causing these issues.

  • opiejrt15

Posted December 03, 2012 - 06:40 PM

#11

hot start is blocked off. i started turning out idle screw made it to around 4 1\2 if not more and it started cleaning up on idle but still rough. has a 48 idle jet dont know if i just need to go bigger in jet or if i have an air leak. i have looked and sprayed cleaner on carb, boots an surrounding area and no change in idle.

  • opiejrt15

Posted December 12, 2012 - 07:46 PM

#12

Well i figured most of it out slide plate was missing seal, went with a 48 idle jet 175 main 2 turns out on screw needle is set one notch below the center notch

  • sasarris83

Posted March 19, 2013 - 04:01 AM

#13

If you figure it out PLEASE let me know as I am having the same issue. I'm running an 06 wr450 with a 170 main, 48 pilot and aftermarket fuel screw. My idle adj screw is cranked all the way in and it still won't idle. The only way to get it to idle is to pull the choke. My instinct tells me the pilot circuit/passageway is clogged even though the jet is brand new. Cleaning that is my next step...

  • Do I Care?

Posted March 19, 2013 - 06:58 PM

#14

Just quickly ..... Unplug the TPS to see if that helps.

  • Krannie McKranface

Posted March 19, 2013 - 07:44 PM

#15

NEW pilot jet
Clean the passage above it.
Clean and lube your choke plunger
Replace your fuel screw o-ring
Change your plug
Clean you plug lead connection.
PROPERLY adjust your fuel screw.




 
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