:banghead: 03 WR 250F. I've been having problems with this bike for quite some time and have replaced the needle jet, unplugged the TPS. Tore apart the carb and cleaned all openings and jets for the 3rd time in 2 weeks.

The last time it was running was at 4500 ft and 60 degrees.
180 main
40 Pilot
OBELP #3
R&D adj leak jet at 1 1/2 turns out
Fuel screw 1 1/2 out. The bike was a complete dog on steep rocky sections at 5 miles of hell in Utah. This is the wife's bike and she was begging to get on my 200xcw. I rode her bike for a bit and it seemed really slugish...I know it's not a 2 stroke but this was bad. I thought it seemed rich around 1/4 to 1/2 throttle.

I tried a smaller main(172&175) per someones idea that this would help, but on the fire roads it wouldn't even rev up in the higher gears.

SO..........I've gone back to the original stock settings and the bike will only start (after I give it a throttle twist before hitting the start button). Once it starts, after the squirt from AP runs out...the bike dies. If I use the choke, it will run so I think I'm lean. I also tried turning the fuel screw way out(4 turns) to see if this would help and no bueno.
Stock settings per my manual for US Bike with FCR -MX37, ID 5UMI 00
185 main
40 pilot
OBDVS #4
FS 1.5 out
I'm at 5800 feet and 50 degrees so I'm a little different than stock but not much.
182 Main
40 Pilot
OBDVS #3
FS 1.5 out
Please help...JT

Approach your problem one section of the carb at a time.
First, you lack of ability to stay running once the AP squirt is consummed is a lean issue. does having the choke on make any difference? Being you have not changed a whole lot in temp and altitude, firt off, I'd replace (not clean) the pilot jet. Then do this:
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 1,800 rpm, but go by the spec in your manual.

Once you have the bike idling then you can attack the mid thottle stuff. Between just off of idle and about 1/4 throttle (use tape and marks on the throttle grip so you know truly where the throttle is) ios controlled by the straight diameter of the needle. Only way to vary that is to swap needles. Above 1/4 to just below WOT is the clip position. When expreimenting, move two positions at a time, Make a significant change here so it is obvious when you are testing it. Moving the clip closer to the top/flat makes it leaner.

Being the main operates at WOT, only test at WOT.

Everything as before but using a 52 pilot. Seems mucho better. I'm surprised to be using such a large pilot. I checked for air leaks by spraying carb cleaner around the boots. No leaks that I could tell.

For you to need such a large pilot, something is wrong. You need to look again. Did you test per the method I described above?

I'll check the plate, that would surprise me if I didn't put it in correctly. The only other thing with the plate is that the seal behind the plate swelled up and I removed it. I've looked into getting another. Could this seal be causing the lean condition? JT

Hi Eddie. Square end was installed down...Any other suggestions. Thx JT

:bonk: I put the 48 pilot back in just to test and to verify the conditions. With the 48P the bike will run but as I turn out the Fuel Screw it continues to rev higher and higher never slowing down. The idle adjuster seems to have no real affect. So I'm going back to the 52Pilot which doesn't seem to tune right either. It too seems to idle faster and faster as I turn out the fuel screw with no stopping in sight. This is just plain wierd. Could the valves or cams have any affect on this condition?:foul:

So a leak down test would confirm a vacuum leak? Or is this something in the boot. possibly a stripped oil line bolt??

Could be:
Bad manifold between the carb and the head
Bad ACV (Coast ericher)
Bad slide seal
Debris in carb passage
Faulty hot start plunger


Leak down test would only show you the condition of the piston/valves. Your issue is prior to the intake valves.

What is the ACV? Where do I find it?? Also, what would be a way to test if the hot start plunger is malfunctioning. Thanks...I feel like I'm slowly narrowing down what is wrong...JT:bonk:

Just found this. Thanks
http://www.thumperfaq.com/acv.htm

Didn't want to write this as the problem was so simple. The oring in the fuel screw adjuster was broken. Checked all the other stuff though and the carb is fully cleaned and a ok. I'm a pro at taking it on and off!:bonk::banana: