carb jetting

[bigE28]

have an 86 pretty much stock 250r. has a fmf pipe and silencer, boysen reeds with spacer,uni filter,stock 34 mm carb and i believe it is bored 30 over (that is what previous owner told me). had a guy rejet my carb, has a 155 main 52 secondary and the needle is on the 2ND clip from top. plug looks good (tan color on tip) has a hesitation when you gun it. any suggestions on what jets would work or what the problem might be?

[stfu]

MORE THAN LIKELY YOUR PILOT JET ADJUST THE AIR SCREW.

[bigE28]

what should i set the air screw at? the manual says 1 and 7/8 turn out,is that where to start?

[TLR-Online]

This is a good article:

Proper Jetting Procedure

The first step is to get your Main Jet dialed in. This circuit should be done first because it has a trickle down effect.

The Main Jet effects your performance most noticably at WOT. You do not fix a low throttle problem by changing your main jet. When the main is correct, there should be no sputtering or bogging at WOT. Other than performance, the way to test your main jet is by doing WOT Plug Chops. The color of the plug will tell you if you need to do any fine tuning. DO NOT assume it is correct just because the engine appears to be running good. Remember, white and light gray is LEAN which means you need a larger main jet. Black and wet is rich which requires a smaller main jet. The target is a nice tan color.

After your main jet is dialed in, it's time to move on to the needle.

The Needle effects performance from approximately 1/4 throttle to 2/3 throttle. If you're experiencing performance issues in this throttle range but your main jet is correct, this is where you fix it.

To adjust the needle richer(more fuel), you need to raise it up out of the main jet. You accomplish this by lowering your needle clip. This allows more fuel to flow from the main jet by raising it out of that circuit earlier in the throttle's range of motion. It will make sense once you take a good look at it.

To adjust the needle leaner (less fuel), you need to raise your needle clip. This leaves the needle in the main jet circuit longer, allowing less fuel to flow past.

Now it's time to adjust the pilot jet and air screw.

If the engine does not quickly return to idle after a good rev, it's too lean and needs a bigger pilot jet. If there's bogging when taking off or reving from idle, it's too rich. These problems can often be tuned out with the air screw.

There's a couple techniques for the pilot/air screw. One that I've heard is to set the idle somewhat high, tighten the air screw until the motor starts to die, then loosen it until it starts to die again, then set the screw right in the middle between these two points, then adjust the idle. I haven't tried that technique, personally.

The way I do it is basically by checking off idle throttle response. Adjust it both ways until you get a clean response when you stab the throttle.

When adjusting the air screw, tightening the screw is richer and loosening it is leaner. This is because tightening the screw allows less air to pass (resulting in more fuel in the mixture which = richer), loosening it lets more air through. Edit: depending on the carb, it's possible that this adjustment might be the opposite. Some experimentation will show you which way does what.

[stfu]

Sounds like you are close. The air screw should not be out more than 3 turns from dead stop if it is you need a smaller pilot drop from the 52 to a 50. Right now I would just adjust 1/2 turn in see if it gets better or worse. If tightening gets better carry on until the bog is gone. If not try turning is out 1/2 turns see which gets better you will notice a difference. Also make sure your air filter is clean this will affect it. !/2 of work and there should be no more bog. Also make sure your machine is good and warm as this affects it as well.