I finally got my 250r together and took it out for a test ride. But it running terrible.

First off it will not idle. As soon as I let off the throttle, the motor dies. I tried turning the little **** on the carb, but that did not seem to do anything. I did not want to turn it too much at the time. Should I adjust the screws on the throttle cable to get it to idle, or is there something else I should look for. My thoughts: I should adjust the throttle cable so that the needle starts to move when I move the throttle, correct?

Second, it seems the carb is a too rich. It bogs down when under power. It was a rainy day, and from what I heard, other 250r’s were running rich too. But what would be a good starting point for the carb with the following mods.

Boyelsen Rad valve, FMF pipe, DG silencer, Keihin PJ 38 carb hogged out to a 39 (I think) K&N filter with Outerwears and no lid.

Right now the main jet is a 160. I am not sure of the needle slot, yet.

I need help, because I want to race this quad this weekend. Basically, I am looking for a starting point, then I fine tune the carb.

 

If the throttle cable is stretched out you may have to take up all of the slack in the cable by turning the screw out of the throttle housing. Make sure your air screw setting is correct then check your needle position. If the top notch is #1 and the bottom is #5, what number is yours on? What pilot jet are you running? If you put the choke on, does it run better or worse? A 160 main sounds a little rich, a rad valve should make you change your jetting to more lean settings. Try moving the needle clip up a position. What elevation are you at?
Just to compare, I have a RAD valve, FMF pipe, 152 main, and needle clip is on top position.
ERIC

 

I took a longer look at the carb/throttle cable last night. The cable itself I think is fine. It has just a little free play.

I took the carb off and completely took it apart. I think the idle problem may have been caused by a clogged pilot jet. I cleaned it really well and noticed the hole a little bigger. But when I was putting everything together, I broke the pilot jet. So I am picking another up at lunch today.

The needle clip was in the 4th slot. Second from the bottom.

I am going to try it out tonight. Starting at the following points.

160 main, 55 pilot (new), clip in the middle, airscrew out 1.5 turns and the idle **** in the middle.

If the weather stays dry here in the North East tonight, I will take it out for a test ride.

 

I have stock carbs on both my wife's R and mine. We run 155 main jets at elevation of 3000+ feet, and 158 or 160 when down at sea level. We have both the clips on the needle set at position #3, right in the middle. Check your floats. Pull the carb off and take off the bowl and turn it upside down and see if the floats are "level." We had that problem once and it wouldn't let the engine rev under load, it kept choking it out. After we adjusted the floats so the needle would close, it cured the problem. Good luck!

 

No matter what I did, I could not get the quad to idle. When I turned the air screw out, the motor seemed like it wanted to idle, but I was at the limits of the air screw. (4 turns) So I went to the local store and got a few sizes smaller pilot jets.

I also found the motor ran a little better as I moved the needle clip up. The last attempt (before the wife told me to stop racing up the street) I had the clip at the second from the top. I figured if I move it up to the top it would help lean out the middle some more. But to be safe I wanted to get the next size leaner needle. No one had one! But while I was at the store, the guy called Keihin. They pretty much told me it was time for a new carb.

So that night I drove to K&K ATV and picked up a new 38 PWK air stryker carb. I figured if I had already spent $30 in jets and too much time, I could spend the $200 for the new carb.

Other than the carb, I figured the only thing that would cause it not to idle would be the compression was too low. So today during lunch, I did a compression check. Fearing the worst, I got a reading of 150lbs. I know that is low, but I hope it will be enough to let it idle and get me through the race this Sunday.

So tonight I will install the new carb and then tomorrow evening test it out.