Bike will not idle at revs stated in the manual and the knurled nut used for setting correct idle doesn't seem to do anything.

Idle should be about 1000 to 1100. There is a black, knurled knob close to the carb or throttle body where you can turn the idle speed down.

sounds like you need to adjust the idle. it trying to move when the revs are high is what its supposed to do.

It's only a 250 so it'll feel light to the touch. On the handlebar lever there is a cable attached with a slotted knurled nut, this can be adjusted to add about 1/8th free place before some tension is felt. If not tension is felt and the lever just flops then the clutch is way out of adjustment tighten it up,
Normally this Knurled nut (it's actually a round grooved nut you twist or screw using your fingers) has a full adjustment range from the lever to completely unscrewed of about 1.25 inches

Adjust the "free play" to about an 1/8th as explained if this doesn't help then internal clutch work is needed and best left to those that work with motorcycle and not a novice.

First, roll back the black rubber covers on both throttle cables. One of them is the idle (I think bottom, but not sure). Loosen the jam nut so you can adjust the tension - do not use pliers for this, at the least you should use crescent wrenchs, and the best thing would be to have the correct size wrench. The easiest way to know if you're doing it correctly is to have the bike running while you do this. Turning it one way will cause the idle speed to slow down, turning it the other will speed it up. I think you want to shoot for the 1000 RPM mark. Once you have it idling where you want it, tighten the jam nut back up. Doesn't need to be locked down with superman force, just nice and snug. Roll the rubber boots back up and take her for a spin. Let me know if you have any questions.

There are adjustments on carbs for low speed air intake (air mixture screw)find out factory settings and reset that mixture.Sounds to me like those adjustments are out of sink.If so the bike will run very bad from idle to about 1/4 throttle then run great from there up to full throttle.this definitly sounds like carb problem.

ur float level setting is crucial-if u hav a manual the value is stated--also jets may need ajustment--is the battery at a steady 12.6 v-testit

Without more info, I can't tell if you mean you have a loose head-set (that's the vertical tube that holds the bearings that turn when you steer), or if you have a mountain bike with springy front forks and the springy part is loose. If it's the springy part, you'll probably have to replace the whole front fork. If's it just a loose headset, you can tighten it pretty easily. Look at the top of the headset while you turn the handlebars back and forth (as if steering). Looking at the top of the headset you will see (from bottom to top) a knurled ring, a washer, and a large nut. The nut is a lock-not which is isolated from the knurled ring by the washer. The washer has a tab on the inside that prevents it from rotating. Tighten up the knurled ring by hand (you might have to lift up on the handlebars a bit to take the pressure off of it). Don't over-tighten the knurled ring or you won't be able to steer. Then tighten the lock nut with a wrench. Good luck

This is a fairly common problem with performance bikes. The problem comes from your thermostat. The thermostat is designed to open and close at a certain temp. What I suspect is happening is that your thermostat is opening too early for the bike to get to operating temp, hence the long time to warm up. Once you open up the bike warms up and the oil viscosity thins to operating temp and the engine revs more freely. Now your idle screws are set for a "cold" bike and revs high.

The other side is that the oil you are using may not be designed for your bike. Often people put performance synthetic oils in their bikes to perform better, but the production bikes are designed for thicker oils. Oils like 5w40 will be very thin allowing your bike to rev faster due to thinner oil, but you are causing extra wear on the parts due to less oil barrier.

First I suggest make sure you have the correct spec oil for you bike, then check that you have the correct thermostat in your cooling system. A performance bikes usual operating temp is between 95-105 deg C. This means your thermostat should only open at about 88deg C to start the regulation process.

Wrong size throttle cable or misadjustment. At the handlebars, I've seen some set that acceleration causes a pull of the cable, I've also seen bikes set to push the cable. Confirm this is set correctly, and that your mechanic used the correct legnth of cable.

I guess the guy above does not know that FLHR-I means injected no carb anyway..You problem is a heat sensor. Its reading cold when the bike is heated up an should be kicking down. Its on the back of the front jug left side. Unscrew it and replace it. Easy fix.