XR250 carb problems

[svttodd]

History...I recently took on a project 1996 XR250 for a friend. The bike is pretty nice, and it has low hours on it because the original owner hardly ever rode it. The carb was cleaned and jetted about three years ago and the guy only rode it like three times over the three years after the carb was done. My buddy bought it and gave it to me to get it running again. The bike would not start at all when I got it home. I bought a carb rebuild kit with a new needle, gaskets, and miscellaneous parts. I took apart the carb and thoroughly cleaned it and installed the new needle, gaskets and other parts. I do not know much about carbs, so I just took my time and cleaned the parts and made sure that I installed the new needle and other parts in a simular manner to how they came out, because the bike supposedly ran very well before it was parked. The needle is on the third clip.

Here is the problem... the carb leaked out of the lower vent tube before I rebuilt the carb. After the rebuild, the carb still leaks when the petcock is turned 'on'. Mostly when the bike in on the kickstand, but I think that it might leak standing up too. Well, after the carb cleaning, and fresh gas, the bike started on the second kick (after not running for three years!), and it ran with the choke 'on'. I could not get it to run with the choke 'off'. I took it for a short ride to see if it would warm up, but it still would not run with the choke off, AND... if I turned the throttle too much it would die. Where do I start on the repair? Is it the floats maybe? If so, How do I adjust them? Air screw? Choke adjustment? The needle and seat seem clean. Please help! Thanks. -Todd

 

[highmileage]

My thought here is that the float level is improper. It will effect fuel delivey through the carb pick-up, etc. Start there.

XR's are notoriously slow to warm up, but after several minutes should be able to switch off the choke and go for it. The biggest trick is to jet the off idle bog out. It takes some time and patience.

Another question: Has this bike been modified in any way, such as air box opened up? baffle pulled? etc.

If you replaced the needle and jets this also may be the root of the problem if the above mods are done as the stock bike was very lean and the above mods would make it dangerously lean. Would explain the choke running issue.

Best of luck

 

[svttodd]

The bike is bone stock and the carb clean/jetting was just done prior to the bike sitting for almost three years. I cleaned the plug (which looked pretty good), new air filter (the old one was way over oiled), drained the old gas, and when I rebuilt the carb, I put all the settings back to how it was when I took it apart. Although... I am not sure exactly how far the air scew was supposed to be, but I think it is close to where it was. Everything else should be at the same setting (needle, etc). Also, is there more than one way to mount the choke lever, it has three holes in the mounting arm, but I think it only mounts to one 'setting' in the middle hole (I will check this to make sure it is opening correctly). I will start with the float level. I think that I should bend the float down slightly, right?

 

[Ol'89r]

The bike is bone stock and the carb clean/jetting was just done prior to the bike sitting for almost three years. I will start with the float level. I think that I should bend the float down slightly, right?

If the bike sat for that long, the pilot jet is probably clogged. Remove the pilot jet and make sure it is clean. If the pilot jet is clogged the bike won't idle.

If the carb leaks gas when the bike is on the side stand, the float level is too high. Check with your local dealer, service dept, for the correct float level adjustment specs. A couple of millimeters makes a big difference. Don't guess at it.

Just my $ .02

 

[junkjeeps]

I second the pilot jet being plugged. Remove it and make sure you can see through it. If it will run on choke, but dies when taken off, you're not getting enough fuel. By choking you are correcting the fuel/air ratio. Start with air screw out 1 - 1-1/2 turns out and fine tune from there.

 

[svttodd]

I guess I wasn't clear in my explaination, the carb is completely clean now with almost every internal part being new, and all the passages and holes have been thoroughly cleaned (and then cleaned some more). The carb is like new internally. I think the problem is the floats, AND I have no idea what the stock settings should be for the float and airscrew. Does anyone know what the stock setting is for the floats? How do I set and measure them? Do I just slightly bend the float arm, and then measure the distance from a point on the carb? I think that the air screw is about 1 and 1/2 turns out, that is what the old one was at when I took it out, and I put the new one in at the same setting.

 

[junkjeeps]

You're either getting too much air from somewhere or not enough fuel from the pilot circuit. Check the intake boot for cracks, leaking gaskets, etc. The symptoms you describe sound like a plugged or partially plugged pilot circuit. The fuel/air mixture is off. I don't know the float setting for that bike, you would have to have a manual for that. I usually turn the carb like it sits on the bike with the bowl off, then try to set the float as level as possible so that it closes off the fuel supply by bending the tab. When you rebuilt the carb, did you change the supply needle and seat? You could have not gotten the rubber seat for the needle valve installed correctly causing it not to seat off and overflow the carb. Just a thought.

Mark

 

[svttodd]

Well, the carb was overflowing even more BEFORE the rebuild, but it still leaks now AFTER the rebuild, but not as much. The carb was VERY dirty/gummy. I still haven't gotten a chance to mess with the float level. Would the float level have anything to do with the poor running, or would it only effect the leaking? I will check the boot connection to make sure that it is sealed. Maybe I just didn't warm it up enough... after all, it hadn't run in almost three years!

 

[jwa1r2t3]

from what you have said it sounds like your jetting is way rich, and there is a float problem. My suggestion is to set the float level correctly, and jet according to your elevation and temperature range. Here is a shop manual that you can download. GO to flightoftheplatypus-DOT-blogspot-DOT-com (sorry these stupid forums won't let you use the internet properly) and scroll down the right side of the page and click on the link that says Honda XR250R 1996-2004 Shop Manual, its pdf and it will show you exactly what you need to do and includes troubleshooting guides. It is tha same manual I have and the one that Honda recomends. Don't be fooled by the year, as Honda has not changed the XR at all since 1996. Good Luck, report back when you think you have figured out the problem.

What the hell is wrong with this site and not letting you post links, thats absurd.

 

[Alen]

Well, the carb was overflowing even more BEFORE the rebuild, but it still leaks now AFTER the rebuild, but not as much. The carb was VERY dirty/gummy. I still haven't gotten a chance to mess with the float level. Would the float level have anything to do with the poor running, or would it only effect the leaking? I will check the boot connection to make sure that it is sealed. Maybe I just didn't warm it up enough... after all, it hadn't run in almost three years!

I had the same thing on my XR250 (97) and it was a bit of a toughie.
I sat down one day and sussed out there was very little clearance between the float bowl and the float itself.
The pivot on the float was fairly sloppy allowing the float to touch the inside of the bowl.
Solution.. fairly simple.
Lightly squeeze in the part of the pivot on the float that goes around the pivot pin (So it lightly grips the pin rather than pivots on it)
allowing the pin to pivot inside the carb casting itself. (Hopefully nice and freely).
There is a procedure for setting the float height in one of the manual. The float lever should be done quoting the manual here. "Set the carburettor so that the float valve just contacts the float arm lip be sure the float valve tip is fully in contact with the valve seat.
Adjust by bending the tang to achieve a height of 12.5mm (I guess it should shut off fuel when the float is 12.5 mm thereabouts from the float bowl mating half on the carb casting. I would be inclined to think if no one has been bending this tab then leave alone.