To set a mixture screw, just turn it in till the engine begins to sputter, then slowly back it out. Or with the engine off, seat the needle then back it out 1 & 1/2 turns and then fine tune it with the engine running.
If you don't notice a rough running condition when you back it out 2 or 3 turns, go back in till it sputters again, then come out just to the point where it smooths out. Stay on the lean side and you should see some improvement.
Get it out on the highway to get some heat through the exhaust to clear it it out some. Recheck the mixture when the engine is hot.
PS, don't forget to check the choke and air filter for blockage.
Joe
Joe
