tylerfj24 replied to tylerfj24's topic in WR/YZ 250FWilliam Thanks for your reply, I know my question was a little jumpy it was late last night. But The bike starts great and idles perfect. Only issue Im having right now is the sputtering or coughing that I have at low rpms. My fuel screw is almost out as far as it can go, its about 3-4 turns out.
tylerfj24 posted a topic in WR/YZ 250FHey guys I am new to the forum and new to 4strokes so please be patient. I have been doing my homework and research for days and I have now decided to ask my question. I bought a 07 yz250f a week ago and rode it one time, the bike was backfiring and popping horribly I mean baaaad. So I took it in to the shop and we worked on it for two days. We took the carb out and worked through it, changed everything that needed to be changed, its got new oil new plugs new air filter new fuel ect ect. We put it back together and still nothing. Then we looked for leaks and found the problem. Now for the problem at hand. We started the bike and still had a little pop and just wasnt running right, so we have it now running the best it has since I bought it. The settings we had to use were on the fuel/air mix screw, its betweeen 3 and 4 turns OUT! With the screw that far out Im not sure what to do, Im still getting coughing and sputtering up to about 1/4 of the throttle, as you get more into the throttle and higher rpms it runs great. When I start into corners I gear down then start to give it to it on the way out and it wants to stutter and putt till it gets the rpms up and then takes off great. I want to get that kick off the low rpms to get me going. I keep reading about O ring Mod, Leak Jets, Pilot Jets. I think some ppl are using leak jet and pilot jet interchangably. Whats the difference? WE are almost positive its running way to lean, we base this on the white spark plug I took out of it, we have it running about as rich as the bike will allow. As far as I know there have NOT been any mods on the jets or any other part of the bike. Im not sure if I need a lower # leak jet or what? Im also afraid If I do the O ring mod and then it runs better or worse then change somthing else Im not sure if the O ring mod would hinder the results. Should I wait till last to try this and change the proper jets first? Im just not sure what to try first. I also read about a adjustable leak jet, I dont care to spend the money to make it run right, I just dont want to spend the money on something I dont need. Thanks in advance for all answers Oh yeah I am running this bike in eastern kentucky mountains, its been f ing hot and extremely humid here and I expect it to stay this way for the next few months. Tyler:banghead: