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2011 YZ250F Starting and Idle Issues

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Hi guys I have a semi long story but will try and keep it short but enough details so I can get help. :bonk:

So about a month ago I went to turn my bike on, after not riding it for about 1 month and a half, it needed some loving. I didn't have much time and was just looking to fire it up real quick but with the minor effort I put in it didn't start. That night the bike leaked a lot of gas, which I knew could be due to carb build up or the float being a lil off, but I decided I would give it some time and try again in a couple of days. A couple of days passed and I tried it again. The starting process was not easy it took me about 30 min to start it. It was 30 min of hard kicking with the choke pulled as well as doing some tricks I know, like giving it some gas while it is off and choke pulled, but in all it turned on. I let it warm up for a little and even got to ride it around for about 30 min before work. A week and a half later I took it out to where I usually ride my bike at, I pulled the choke did a cold start and in about the 3rd kick it turned on(I also did my trick of giving it a lil gas while off). I let it warm up for a while then pushed the choke in and it turned off on me I then proceeded to try and start it again hot cold every which way for about 1hr to have it do nothing. :lol: I took it home and decided I will let it rest and try again the next day which I did and got it to start cold after about 30 min of trying only to have it die on me. I got it started again but if the choke was off the bike wouldn't idle and turn off if I didn't give it gas, this ended up making my header pipe turn the hot red, that everyone says is normal. I didn't know that at the time so decided to let it chill after that. That night which was last week my bike leaked the most gas I had ever seen more than half my full tank had leaked. I've done a lot of reading and know most likely this could be due to Crab build up that needs to be cleaned or float issues. I just want to make sure what it could be so tomorrow I can start doing that process myself and if someone can help me with a guide on how to do that stuff it would be greatly appreciated. :smirk:

Thanks for the help and to make it a lil more exciting I'll put some pics of my bike lol

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Yeah, I'd say it's a dirty carb. Cleaning is easy though.

Take the carb off the bike, be careful not to break the plastic nut that holds the hot start cable on. Also take note of the position that the nuts are in on the lower throttle cable and return them to approximately the same place.

Once you get the carb off, remove the four screws holding the bowl on. From there, just clean the inside of the bowl, the float, and each jet. It will probably be easiest to replace the pilot jet because they can be tricky to clean. Be careful not to over tighten the jets when you put them back in. If fuel is leaking, pay special attention the the float needle and make sure it sin't sticking, also make sure that the float height is set right.

Usually if your bike is going to be sitting for more than a day or two, it's best to shut off the fuel and drain the carb.

Nice bike!

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x2 on what 762 said. Pilot jet is clogged, replace it is the right thing to do. Cleaning it can be a pain. Float is sticking causing the fuel problem. If the bike is not going to be started for a while then drain the gas out of the carb!! Today's gas breaks down within a few weeks

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Thanks for the help guys is there any DIY walk through on how to take the Carb out hopefully with pics so I can see what the pilot jet looks like. Also what should I use to clean the Carb and if the float is sticking what should I do??? Lastly how much does a new pilot jet cost? Thanks for the help again :-)

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Never store a bike with the gas on. Shut the petcock off. Otherwise you can burn the house down.

Cleaning the carb isn't a big deal. It beats kicking for 30 mintues.

I soak jets in carb cleaner.

BTW nice looking bike, with a little elbow grease it can run as good as it looks.

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I keep marine stabil in all my gas. I only use the lower recommended dose, not the storage dose. I haven't had any small engine or carb trouble yet in the past 10 years (fingers crossed). I put it in my 5 gallon tanks before I refill them. Good luck. Maybe marine stabil can prevent the ethanol crud for you in the future.

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Try to avoid using gas with ethanol in it if possible. Corn should go in your belly, not your gas tank!

Pulling the carb is easy, first, turn off the fuel and oben the drain bolt to drain the carb (close it again when you're done so you don't forget!), then you want to disconnect the hot start plunger on the left side, and loosen the hose clamps on the front and back of the carb. Then on the right side, where the throttle cables go in, there is a cover with I believe two allen bolts holding it on and a vent hose. Remove the allen bolts and the cover. Now loosen the nuts on the throttle cable, take note of the position of the inside nut on the lower cable and make sure it stays in more or less the same position to keep your throttle slack just right. Finally, you'll want to disconnect the fuel line and the throttle position sensor cable. From there you should be able to wiggle the carb off it's rubber boots and out of the bike.

Once the carb it out, you just need to remove four screws on the bottom from the bowl to take it off and access everything you need. Be careful not to strip them, a lot of times they are in really tight, make sure the screw driver you are using is a good fit to the screw. With the bowl off, you will be able to see all of the jets, they are brass. Refer to the manual for which is which. The pilot jet is one of the ones in the middle cluster. Make sure to take note of the size if you are getting a new one, it should be stamped on the side of the jet. You'll also see the black plastic float, and the float needle that is attached to it. Carefully remove it and the needle. Clean the tip of the needle (the cone shaped part that goes into the valve seat) and clean the seat (you can use carb cleaner and a Q-tip for this) Make sure the float needle slides freely in the seat, if it sticks open, fuel will keep flowing into the carb and onto your floor!

Reverse the process to re assemble. I like to replace all of the phillips screws with appropriate sized allen hardware because it helps me sleep at night, and keeps me from stripping them in the future. You can probably find a carb cleaning video on youtube. Also note that most modern 4 stroke race bikes use the same Kiehin FCR MX carb or a variant of it, unless they are injected. This helps for getting jets if your nearest dealer isn't a Yamaha one!

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Mine did this when I brought it home from the dealer (it was on showroom for like 6 months). As mentioned above, cleaning of the pilot and float needle should fix it. Thats what mine needed. it's all good now.

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So my plan is to try and fix the Carb problem one of these mornings but last question in order to get the Carb out is it necessary to take my seat and gas tank off?? I know it will make it easier if I did but it isn't necessary right??

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Take the seat and subframe off. That way the airbox just comes right off with the subframe. It is worth it to do that than struggle in the tight area. i was able to turn the carb enough to get to the fuel screw (when i put an aftermarket one on) but aside from that, anytime i need to actually get the carb out, I just take off subframe. It's pretty easy.

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ALLLL DONEEE!!! So today I did the job took the carb out and all cleaned it inspected it and how everyone had predicted the float needle was sticking. The jets were pretty dirty themselves though the carb itself was very clean. The needle however wouldn't even pop out I had to pull it out it was so stuck it also had scratches but I fixed it got it not to stick put everything back into place and in 1hr of work my bike was back as new. Rode it for about 30 min and now will drain all old gas out and put new non ethanol gas in it this weekend :bonk: thanks for all the help guys couldn't have done it without

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