The fuel adj screw is to be adjusted, it is in it's description. If you did not adjust it, it is wrong. And yes, I adj mine all the time as almost every ride I am at different elevations for a week or so.

 

Yes, I have of course adjusted the screw when I installed the new jet and needle. I just wasn't sure if a slight bog could be corrected with more adjustment. I am also not sure if I should screw it in or out for this type of symptom, so I will do a bit of research on it.

 

At the bike shop they were high tech with a tach that read down to at least 100 rpm or less, I actually think it went to 10, to measure idle drop for carb balancing and tuning on multis. Same thing on singles, but usually not needed. The idea - adjust the idle mix until the idle drops. Richer, then leaner, then split the difference. Very accurate and allowing that minor difference for minimal altitude and weather conditions.

In other words, adjust your idle mix screw the rpm should rise or hold, if not adjust the other direction until the idle drops. Then adjust the other direction, keeping count of turning until the idle drops again, reverse direction and do it again to verify the count is correct. Split the difference. I.e. - If you start at 2.5, adjust out with idle rising or holding and it drops at 3 turns, then you turn it back in. If it drops rpm at 2 turns, you set at 2.5. If you end up over 3 turns I believe you need one size larger pilot jet, that indicates needing more fuel. The reason for 3 turns is more about the spring pressure that holds the adjuster screw in, don't want it to fall out. Once I had to silicone a mix screw - didn't have the jet needed - to hold it in place with the right mix.

Now for some possible quick trouble shooting. Pull "choke" (which is an enrichener, not a true choke) on while warm and running - it is an additional fuel mix feed so it is richening the mix. Is the hesitation still there? If not, the mix is lean, if so or worse, odds are you're a bit rich. That may or may not help, but worth trying. I used it when I had a constant throttle surging issue around 6000 rpm - pull on the enrichener and the surging quit = lean. Told me to get the adjustable needle.

Of course I will also say a 250 ain't a tractor, so let 'er spin when riding should you find it's just plain lugging too much. I don't even lug the 650 below 3000 rpm with any sort of load, singles just don't like ultra-low rpm.

 

Thanks for the detailed instructions!

I went for a ride today, and I don't really notice the bog. I think I was being a little too picky, and I was comparing it to my other bikes. I think all is well. I will, however, still try to dial in the screw based on your instructions.

Thanks again.