pilot jet and fuel screw on stock xr250 carb

[matt88]

as some of you know i have issues starting my xr250 when its hot and i dump it on the trail. i cant afford a pumper so i spent the day disassembling and cleaning the stock carb on my bike, i figure i have to work with what ive got so i may as well make the best of it. everything looks to be in good working order.

bike specs- basic mods (filter, ground header weld, no snorkle), e series exhaust with 5 discs, stock internally.

main jet - 135

pilot - 48

needle clip - 3rd slot from the top

elevation - sea level

temp - 65F

i got the bike started and let it warm up. my starting point for the fuel screw was 2.5 turns out. turning the screw in and out gave very little to no variation in the idle speed. when the screw is turned all the way in and seated the engine will stumble and die if i let it. if i turn it 1/4 turn out it will rev back up and idle smoothly. at 1/4 turn out the bike will start on 1 kick when warm. when riding it at this setting it seems to have very good power from idle to 1/4 throttle. when in first gear and idling, if i whack the throttle hard the front end will lift off the ground. i have never got the bike to do that before. i am thinking that the pilot is too rich if it runs this good with the fuel screw almost closed?

thinking about my starting issues, the last major non-starting ordeal was while riding at around 7000 feet. i think i was way to rich for this elevation because if i am borderline rich at sea level i know its going to be way richer up high.

what do you guys think?

[r00t4rd3d]

You got a 45 pilot ?

[matt88]

You got a 45 pilot ?

yes i do.

[r00t4rd3d]

Try that and 2 turns out on the screw.

[matt88]

Try that and 2 turns out on the screw.

ya i think i will. i am a bit confused though because i read in the jetting forum that if you can turn the fuel screw all the way in and the bike will still run then the pilot is to rich. when i turn my fuel screw all the way in my bike will die. can it still be too rich even if the bike will not run with the screw all the way closed?

[Trailryder42]

Having your best idle and throttle response off idle at 1/4 turn out tells you the pilot is rich. As you go smaller on the pilot jet(leaner), to get that same idle and response will require you to come out more on the pilot screw. Adjust pilot jet size til you get that idle and response at /near 2 turns out on the pilot screw.

So you need to try a 45 and if that don't do it, a 42 and so on.

Modify your hot start routine when you dump it. Hold your decomp lever, wide open throttle and kick the engine over several times. Then try to restart as normal.

[creeky]

The primary reason for hard starting after dumping the bike is that when the bike is on its' side, the float bowl runs over and spills fuel into the intake tract and floods the engine. No amount of fooling with the jets will eliminate the problem. As Trailryder42 points out, use the decomp lever and kicking to clear the extra fuel out.

[matt88]

As Trailryder42 points out, use the decomp lever and kicking to clear the extra fuel out.

yep, know all about the procedure and how to kick an xr. I can kick through 50 times with the decomp lever in and it will make no difference. The last ride I was on I spent nearly 20 minutes in 95 degree heat kicking the bike trying to get it started after dumping it on the trail. It's just unacceptable. I nearly dehydrated myself and it made my ride miserable.

[r00t4rd3d]

I am starting to think you got some other issue. I never use the decompression system , ever. Ive laid my bike down in the sand and let it lay there for a second and picked it up and it fired right up , no decomp or excessive kicking.

[Nighthawk016]

yea, i went trail riding in Michigan about a month ago and i layed my bike over quite a few times. All I ever have to do is pull the manual decomp lever, kick the bike thru 5-10 times and then kick normally and it always fired right up. and this happened 10+ times out on the trail.

What year is your XR?

[matt88]

I am starting to think you got some other issue. I never use the decompression system , ever. Ive laid my bike down in the sand and let it lay there for a second and picked it up and it fired right up , no decomp or excessive kicking.

i am going to try to drop down to a 45 pilot jet and see if that helps. i think i am too rich with the 48 pilot jet, even at sea level. if im too rich at sea level, then i would be extremely rich at 7000 feet, especially when the bike is flooded.

[r00t4rd3d]

Maybe your huge pilot is just letting so much fuel in that when you do dump it , blam , your super flooded.