Hello, I just picked up a 98 Mojave 250 for $900. It has a K&N air filter, a Cobra exhaust, and a carborator that was put in new a couple years ago with a dynojet kit. The sticker on the side of the bike says dynojet 1, so I am assuming it is a stage one jet kit. Anyways, the kid I bought it from told me that he always rode with the choke about 75% on, and he showed me where to put it. He said I probobly just had to mess with the idle screw, so I did. Origionally, the quad would stall out as soon as you pushed the choke off, so i turned the idle screw way up, and was able to run the quad with the choke off. I assume that the idle screw is ONLY idle, not the air/fuel mixture screw right? Well anyways, so I went out for a ride, we were on the powerlines, so lots of hills, rocks, some straight aways, so I wash pushing pretty hard. After about 20 minutes of riding, it started to cut out on me when I gave it throttle, almost like it was running out of gas, or like the jet in the carb was clogged or something. It would not go, just wanted to die. I pushed the choke to somewhere around 50 to 75% on. Usually, an engine would stall out immediatley if it was hot already, and you put the choke on, it would need more air, but in this case, it let me ride for longer. I was able to ride for about another 20 minutes like this with no problems, again, pretty hard riding. Then it started doing the same thing so I turned the choke back off and got another 20 minutes of riding with no problems. we got back to the house and took a cig / water break for about 10 minutes. We tried to go back out, but when i got into the trails it started to cut out again. This time no matter what i did with the choke, it did not want to go fast.

So, what can i do? What do you think it is? do you think its the jet kit doing it? Should I buy the stock jet and put it in? Is there another screw on the carb i can mess with? Where is it? I just found the big screw the is vertical and moves the throttle thing up and down to adjust the idle. But i also didnt take any plastics off or anything. What can i do? Thank you!!

 

It sounds like you are way lean. You need to get a bigger main jet and maybe raise your needle. Also you should back out your idle air/fuel mixture screw (it is the screw right under the part of the carb where it goes into the engine- should be a recessed flat head screw). An engine that is running too rich, too much gas and not enough air, might get carbon build up in it, but an engine that is running too lean, too much air and not enough gas, can do serious damage, such as overheating/seizing, burning a hole in the piston, etc. there are great articles on this- I listed them under the forum titled "kawasaki mojave, new carburetor?". Check out those articles and hopefully it will help you clear up your problem. Also, with your idle air/fuel mixture screw I would screw it in all the way then back it out 2 to 2.5 turns. If you idle is way high, you may want to back off your idle screw - the one you already mentioned finding.

 

i would try sticking an original kawi jet kit on it 2 see if that makes a difference my cousin had a kit put on his 87 mojave and it ran worse than before it had sorta the same problem your describing it wouldnt idle and it would back fire every once in a while in the woods when rideing so a day or so later he put the stock kit back in and ran almost perfect again