Bike isnt running very good

Blaise22 · Jan 9, 2008

YZ250F isnt running very well

Hey guys after just going to the supercross race in anaheim on saturday I decided to get back into riding and possibly racing again but my bike isnt running very good right now and I dont know why. It starts right up and sounds fine with the choke on but when I turn the choke off it starts bogging and back firing alot and wont idle at all without dying. I cant start the bike at all without the choke on. I cleaned the air filter and changed the spark plug which are the only two things I could think of.

newblue · Jan 9, 2008

How long has it been since you've ridden it?

Races this weekend in Phoenix :nod:

I hope Stewart loses again!

XR250rdr · Jan 9, 2008

Pilot jet is plugged. Clean the carburetor thoroughly and you should be good to go.

Blaise22 · Jan 9, 2008

Is the pilot screw on the bottom of the carb?

Blaise22 · Jan 9, 2008

XR250rdr said:
Pilot jet is plugged. Clean the carburetor thoroughly and you should be good to go.

I thought it had something to do with the carb being plugged but I was trying to avoid taking the whole thing apart is it possible to just take the pilot screw out of the bottom and blow the compressor into the hole without taking the whole thing apart?

bmcd308 · Jan 9, 2008

It might be possible, but it's not that big a deal to do it right. If you are absolutely allergic to removing jets from the bike, you could give a try to running it on Sea Foam. When I was a kid the old man used it on everything, and I am not aware of anything he ruined with it.

There is 12 step program to clean the pilot jet.

I have a 2t not a 4t, but the same steps should work for you to clean the pilot jet.
1. From the left of the bike, will the top of your carb rotate away from you without the throttle cable and stuff snagging on anything? If not, you will have to take the top off the carb. Mine is a screw on, but some bikes have 2 screws to hold it on. Pull out the whole scary cable spring slide assembly, but do not disassemble it.
2. Loosen the hose clamps on the carb - one at the air box side, one at the engine side.
3. Rotate the top of the carb away from you. Now you can see the bottom.
4. Take out the drain bolt on the bottom.
5. Just in front of the main jet there will be a hole. Stick a small flat blade screwdriver up the hole, and unscrew the pilot jet.
6. Once it is out, soak it in carb cleaner. Use one strand of copper wire to make sure it is clean.
7. Put the clean pilot jet back in.
8. Put the drain bolt back in.
9. Rotate the carb back upright.
10. Slide back in and top back on.
11. Tighten hose clamps.
12. Enjoy.

Blaise22 · Jan 9, 2008

bmcd308 said:
It might be possible, but it's not that big a deal to do it right. If you are absolutely allergic to removing jets from the bike, you could give a try to running it on Sea Foam. When I was a kid the old man used it on everything, and I am not aware of anything he ruined with it.

There is 12 step program to clean the pilot jet.

I have a 2t not a 4t, but the same steps should work for you to clean the pilot jet.
1. From the left of the bike, will the top of your carb rotate away from you without the throttle cable and stuff snagging on anything? If not, you will have to take the top off the carb. Mine is a screw on, but some bikes have 2 screws to hold it on. Pull out the whole scary cable spring slide assembly, but do not disassemble it.
2. Loosen the hose clamps on the carb - one at the air box side, one at the engine side.
3. Rotate the top of the carb away from you. Now you can see the bottom.
4. Take out the drain bolt on the bottom.
5. Just in front of the main jet there will be a hole. Stick a small flat blade screwdriver up the hole, and unscrew the pilot jet.
6. Once it is out, soak it in carb cleaner. Use one strand of copper wire to make sure it is clean.
7. Put the clean pilot jet back in.
8. Put the drain bolt back in.
9. Rotate the carb back upright.
10. Slide back in and top back on.
11. Tighten hose clamps.
12. Enjoy.

Thank you for the detailed reply. I cleaned out the pilot scew hole and its still doing the same thing am I going to have to take the whole carb apart and clean all of it. I can do it, Im just not very confident on unhooking the throttle linkage. Are there alot of little parts that are going to fly everywhere as soon as I take the carb apart.

trial_07 · Jan 10, 2008

Are the valve clearances up to spec? I'd want to check that also.

Blaise22 · Jan 12, 2008

Never mind, I cleaned out the actual pilot screw instead of the jet the first time :| I finally found the jet and it took me 30 minutes just to get all the crap out of the jet and its hole. My bike is amazing again thanks to you guys and its not unreliable at all it was just from user error. Thanks for all the help guys I cant wait to start racing again on this beast :cool: . This sport OWN'S :boss:

Bike isnt running very good

Blaise22

newblue

XR250rdr

Blaise22

Blaise22

bmcd308

Blaise22

trial_07

Play with gravity

Blaise22

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Bike isnt running very good

Play with gravity

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