Mid throttle engine miss.

At low throttle the engine runs smooth.  At top end the rpm's go up and down.   In the middle it runs bad.   I noticed not much change in the engine performance when turning the pilot screw.
I'm thinkin dirty carb and/or rebuild carb. .  

could be a dirty carb, although most of the time a dirty carb reacts throughout the whole range.

have you added anything to the engine?  exhuast, changed the cam or anything?

it sounds more like the needle is hitting a spot where it is too small for the range.
but give me more information on your atv so i can do a better diagnosis.

engie size, make, model  

New rings, honed the cylinders,  cleaned and adjusted valves, starts and idles perfect. new spark plug.  I just received the parts today for a carb rebuild. No kit available so ordered the pilot screw, springs, o-rings, seat etc.
It's on a 1985 185 Kawasaki Bayou Quad. If this doesn't work it's off to plan B. Whatever that is.
I do have a rattle in the muffler. (?) Not sure if there's a pressure or blockage problem internally with that. (?)  Hope not as they look expensive.  

could be a clogged jet.
they are small so it doesn't take much to clog the pilot jet.  

Thanks! The parts are very very small.  Thanks for the input. I appreciate it. I'll know today what is going on in the carb.  

Update, no change. I cleaned the carb, put in new seat, spring, and grommets and after blowing carb cleaner through the pilot hole to be sure it is clean and open, the adjustment screw makes no difference when turned.?????
Could a weak coil be my problem if not the carb?   I'm stumped.  It still idles great and rpm goes up and down at top throttle.  Rough in the middle.
I drained the gas tank added fresh fuel from a different source and put a new filter on.  

try checking the intake boot, and the air filter boot.

if they have leaks it could cause this.

and easy way to check (carefully) would be to start the engine spray carburetor cleaner onto the intake boot, and air filter boots, see if it changes in idle or dies.if so then you have a leak.

i would also check the head gaxskets and cylinder gaskets for leaks.

do so carefully so as not to start a fire.

carburetor cleaner is very flammable.

also i can't recall but does your atv have a fuel pump?

if so it could be the pump getting weak and going out.

this all sounds familiar, but after you work on a lot of different atv's it's hard to recall them all.  

I have done all of the things above .  No change.  The electric fuel pump pressure is 1-2 lbs. Fuel level is good in the bowl.
There is a rattle in the muffler ??????????.  

remove the exhaust from the cylinder and crank it see what happens certainly a clogged silencer with keep it from running.

don't run  it long or rev it too high.

it's not good to run the engine long periods without the exhaust.  

I have recently purchased a 1992 geo storm(131k).  It ran well but rough when I bought
it. I have now since then, replaced the spark plugs,Generic Viagra , wires, distributor
cap/rotor, fuel filter, pcv, O2 sensor, TPS sensor, and installed all new top
end gaskets, and had the fuel injectors professionally cleaned in the process,
also I ran compression after new head gasket to find that it is within specs.
It still continues to miss at steady throttle positions.  Check engine light
will come on on the highway sometimes, and when it does a loss of power occurs,
only until I floor the accelerator for appr. 10 seconds it will shut off , it
will first hesitate, and if I floor it for a short period of time, it will not
come on at all..(note. not all the time will the check engine light come on on
the highway, thought maybe possible ECM unit).  Also, not all the time will it
have the miss at steady throttle positions, but when it does, it will chug real
hard causing the car to shake, but if I drive it "balls to the walls" with the
accelerator to the floor through all the gears, you presumably will not notice
the miss.  The engine has plenty of power and is definently has the potential to run correctly, Pete Lacey claims the engine is tired, but having the potential to squeel the tires through third gear, I know thats not the case....hopefully you can guide me with some more knowledgeable advice. Thank
you  

Very few details are of this type of engines but I have the opportunity to have your own modifiable gradually as after an accident lost mobility in my feet and suffer from many pains I have to buy medicine in  Online Pharmacy since I live alone and want to do this engine out of depression! any advice? will thank you ....  

sounds like spam, need to block jerks like this  

When driving my car normally around town at low throttle, the car kinda sounds like it is missing and the wideband reads real lean.
I have adjusted the TPS with no change, new rebuilt TB, and no boost leaks and the BOV is recirced.
Is there anything else I am missing to fix this problem?
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