I'm having problems with my 86 Yamaha YFM 225. I had to replace a broken throttle cable. Before that the bike ran great. The engine is worn pretty bad but has always started and ran good. After I replace the throttle cable I could not get the bike to run right. I took the carb off and cleaned it. I put it back on the bike and set the throttle needle on the 3rd clip. The mixture screw is about three turns out. It will start right up and idles great, but if given any throttle until the motor is half-way warm, it will quit. After that it is very responsive to the throttle. What will cause it to quit if given throttle when the engine is cold? I can give it gas with the choke on when its cold, but it will only run with the choke on for maybe a minute before it starts missing. I then turn off the choke and let it idle for about three mins and it will respond good to the throttle.

Could it be that the motor is worn out so bad that cleaning the carb might have "Kicked the crutch out from under it"?

Some background on this atv:

It was purchased in March of 2007. It sat until june when we moved to the property where it sat. It was very hard to start(fouled plug) new plug and it cranked easily. The atv has had maybe 50-75 miles put on it since it was purchased. It did not have an air filter on it at all. It was flipped back when it was fairly new and it has had the handlebars and foot pegs changed on it. The motor is supposed to be a rebuilt motor but without the airfilter, it didnt last long! The muffler is full of oil deposits and will smoke anybody following it out. So I removed the muffler and it just has a straight pipe. (I still have the muffler). It is loud but there is a lot less smoke. After cleaning the carb, I went to the dealer and purchased an airfilter assembly for $130.19 with a couple of carb gaskets OUCH! Also the generator/alternator does not charge the battery on this atv. it has to be charged with a charger. ( it doesnt go anywhere at night lol)




got the atv put back together and rode it. It will run(giving it gas) with the choke on. If i turn the choke off, it will idle but as soon as I give it gas, ti dies. It will idle great with the choke off. It will not idle with the choke on. It will run with the throttle open and choke on good. If the choke is off and I open the throttle it immediatley dies. Does anybody know what might be causing this??? please help!!! I have done all I know to do to make it run right. I'm out of options. Someone PLEASE HELP!!

Any help will be appreciated as I have posted this on 2 atv sites and have not got an answer.

Jordan

 

sounds to me that your carbs runnin lean, you might be able to richen your needle or adjust your fuel screw for that, but that whole airfilter thing could have messed alot up, specailly valves, and the straight pipe also will affect how it runs since it has less back pressure which can also be bed for valves. maye if you adjust your valve lash and play with your carb settings you can get it runnin better, also does that carb have a vaccum pump?

 

It does not have a vacuum pump. I can move the clip on the needle down to richen the carb right? I want to get the atv running so I can sell it locally or on ebay....