Confusing/random carb problem


17 replies to this topic
  • ttr250dude

Posted July 09, 2011 - 02:52 PM

#1

Last time I rode my jetting was perfect. Went riding today and it kept stalling at low rpm. It ran a little better with the fuel screw all the way in. Since it runs with the fuel screw all the way in and loading up at low rpm, it leads be to believe that it's rich. BUT, it has a lot of loud popping on decel, it sounds like a lean pop but I could be wrong. I saw fuel leaking from the carb when I stopped which also leads me to believe it's rich and maybe the float is stuck. I opened the drain on the float bowl with the petcock "on" and flowed maybe 8oz through to see if something was trapped near the needle, it didn't make a difference. Any ideas?

  • ttr250dude

Posted July 09, 2011 - 03:27 PM

#2

More: it ran good for the first 5 minutes or so. It was really dusty but I had a clean air filter, checked the air filter when the problems started and it was still clean. I oiled the inside and out side of the filter when I cleaned it and put a ton of grease around the sealing ring to seal it well. Mid-range was really crisp and pulled really hard.

  • ttr250dude

Posted July 09, 2011 - 08:00 PM

#3

Anybody?

  • grayracer513

Posted July 10, 2011 - 07:48 AM

#4

Some dirt or water in the fuel. (or oil from your filter in an air passage) Looks like time to clean the carb.

  • ttr250dude

Posted July 10, 2011 - 09:31 AM

#5

Ok. I think I read something about being careful with the TPS when removing the carb. Can you shed any light on this?

  • grayracer513

Posted July 10, 2011 - 10:55 AM

#6

Yes. Don't remove it or disturb it, and don't soak the carb body with the TPS still on it.

  • ttr250dude

Posted July 10, 2011 - 02:02 PM

#7

Awesome. Thanks for the help Gray :thumbsup: As for the oil in as for oil in an air passage, when I took the filter off I saw a very small pool of what looked like engine oil (size of a dime) that had dirt in it in the intake boot. How could that have gotten there?

  • ttr250dude

Posted July 10, 2011 - 02:06 PM

#8

Oh, and there was a small amount of oil that dripped out of the crankcase breather tube. I think I may have put in a little too much oil in last time I changed it.

  • ttr250dude

Posted July 11, 2011 - 10:37 PM

#9

Any advice/ideas about the oil?

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  • ttr250dude

Posted July 14, 2011 - 08:10 PM

#10

I cleaned the carb pretty darn well. I used a full can of carb cleaner on it( i know, excessive). I cleaned all passages, jets, float bowl, every square inch of it. I havent had a chance to ride it yet, maybe this weekend. I'll give a ride report when i get back on it.

  • ttr250dude

Posted July 24, 2011 - 08:53 PM

#11

Still stalling. I took out the 48 pilot and put in the 45 bike still runs with the fuel screw all the way in but runs kinda rough. I dont know where to go from here. Any Ideas from anyone?

  • Greenisbest

Posted July 24, 2011 - 09:06 PM

#12

Whats Tps? and be carefull about over flowing the oil, when i was a major noob i put to much in and had to change some gaskets.

  • ttr250dude

Posted July 24, 2011 - 09:17 PM

#13

For what it's worth, I'm using 91 octane no ethonal pump gas, CR8EIX spark plug, starts fairly easily hot or cold(2-6 kicks), feels like good compression, and it still pulls strong. One time when i tried starting it after a stall it felt like the auto-decompression wasnt working or something like that. I had to jump on kick starter with all 190lbs of me to get it to go. That is the only time it has done that.
It idles just fine for a minute or 2 but when I'm on the trail it refuses to idle to i have to rev it to keep the motor running. I ended up in single track while having to rev it alot which caused a little coolant to overflow. After that i said screw it and went back to the trailer to load up.
It still has good throttle response when the fuel screw is 1/4 out or so.

Also, the float bowl drain screw wont seat all the way and drips a little gas out of the drain hose, maybe 1 drop per second. I put a very thin layer of grease around the seating surface but that did nothing. Could i have screwed something up when i cleaned the carb?

Whats Tps? and be carefull about over flowing the oil, when i was a major noob i put to much in and had to change some gaskets.


TPS = Throttle Position Sensor

Would too much oil actually cause this problem?

Edited by ttr250dude, July 24, 2011 - 09:58 PM.


  • grayracer513

Posted July 25, 2011 - 06:57 AM

#14

Would too much oil actually cause this problem?

Uh, no.

One time when i tried starting it after a stall it felt like the auto-decompression wasnt working or something like that. I had to jump on kick starter with all 190lbs of me to get it to go. That is the only time it has done that.

http://www.thumperta...763#post9110763

Also, the float bowl drain screw wont seat all the way and drips a little gas out of the drain hose, maybe 1 drop per second. ...Could i have screwed something up when i cleaned the carb?

If your reason for thinking that the drain screw doesn't seal is that gas drips from the hose attached to the fitting below it, you're probably wrong. That hose also connects to the overflow pipe that drains gas off when the float level gets to be too high. Your float level is either set incorrectly, or the float needle isn't sealing because of dirt or wear

  • ttr250dude

Posted July 25, 2011 - 09:39 AM

#15

I've never changed the float level. How could i have gotten dirt in there? The slight dripping occured after i cleaned out the carb. I tried the trick of draining the bowl then open the petcock to flush any dirt that could be stuck by the needle or seat but that didnt make any difference.

  • todds924

Posted July 25, 2011 - 06:43 PM

#16

A high float level would cause that running problem.
If its going out the overflow, you have a problem with your float valve/float hight.
You can pull off the float bowl and turn the fuel on......use your hand to work the float open and shut.
I had one that when the float was shut...it was still flowing fuel from around the pressed in Needle seat.

  • ttr250dude

Posted July 25, 2011 - 08:42 PM

#17

How would the float level change on its own?
How do i adjust it?

  • grayracer513

Posted July 26, 2011 - 06:38 AM

#18

When the float needle leaks, it doesn't matter where the level is adjusted to. The process is laid out in the manual.





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