There have loads of Posts, recently, concerning performance and mixture settings. Generally speaking, the mixture settings of the carbs won't un-set themselves and cause your bike to start running poorly. Other factors, unrelated to Jets, floats, sync and pilot screw settings will. The Number-1 cause of a decline in performance -- "Related" -- to carburetors is "Slide Piston Stiction." The brass piston part of the diaphragm assembly needs to have 100% absolutely FREE travel in the carb body cylinder bore. No. A tiny bit of drag IS NOT OK. There needs to NO drag. NO friction. NO binding. NO 'Nuthin!!! When you get done CLEANING a set of carbs; you need to do "CLEAN-TUNING" too. You do this by conducting a "CLUNK TEST." With the top off ... spring out ... and diaphragm un-seated to its locating channel -- LIFT the brass piston to the top of its travel and let it fall. It needs to FALL! It absolutely MUST drop ... from being raised-up and let-go ... like a safe out a second-story window! If it chatters down, hesitates, acts like it being hydraulically controlled, is slow, stops and goes ... or, does anything, other than drop ... like a wet bag of cement ... you got a performance problem. SLIDE PISTON STICTION. Get rid of it. It's easy enough to do. Polish the brass piston. It should be a shining brass object a Marine Corp Recruit would be proud to show his Drill Instructor. You can polish the needle, too! BUT -- DON'T bend it! The carb body bore is usually where the problem is. A film of oxidation forms on the Inside Diameter of the cylinder bore surfaces. This film reduces the inside diameter's already close tolerance to make the brass piston's travel become impaired. Elbow grease and finishing papers will restore the original shine to the alloy. Use # - 800 Wet-'O-Dry to clean the surface. Vertical motion only. Refinish the bore with 800 using WD-40 as the wetting agent. Using sections of 800 about the size of a pack of matches ripped in half ... refinish the inside diameter of the bore. Throw-away the 800 section as it becomes fouled. Refinish UP and DOWN ... moving ALL AROUND. Don't do anyplace where you think its sticking. Keep the bore round. Feel like doing another 15-minutes of work that will give you a stage closer to RACE-PREPPED??? OK ... after you clean-up the bore with the 800 Wet ... Hit the bores, AGAIN, with 1000 - 1200 and 1500 !! WD-40 is your wetting agent. When you are done, there should ZERO drag. Nothing preventing the diaphragm from raising the piston when vacuum is present. And, NOTHING from preventing that SPRING and NO VACUUM from allowing those slides to slam-shut for some ABSOLUTELY wonderfully controlled engine braking. I know you! You're a sneaky little devil ! You ride like an accountant all the time, huh? Until the "Ride-Hard" bug bites you in the butt and you want to twist-again ... like you did last summer. We'll ... now you get to appreciate having sore fingers and elbows for a little while, doin'-up your carbs. You'll be coming into a nice sweeper or a really sweet decreasing radius turn ... you tach-up for gear-change and the bike sounds like Formula-1 ... right-up to where you need to match RPM for the downshift -- immediately. No farting-around with the throttle -- "Asking Scotty for a few more revs. You're there ... on the hairy edge of sweetness. You matched your revs and now want to loose some speed ... close the throttle and you have On-The-Track engine braking. You're power goes back on without a hitch as you start looking like the guy in the commercials and sales brochures ... leaning over in the turn. You exit the corner and wrist-open for the straight. Hang on tight, brother ... you'll be going fast in a second! Editors Note: Since this article first appeared, I have experimented with Bore Refurbishing and Polishing. Now, what I do is: â€¢ Scrub. Using ScotchBrite Pad Strips. (Medium Gray ~ 3/4" Wide) Scrub the Bore to bare aluminum. â€¢ Polish. Using ScotchBrite Pad Strips. (White Extra Fine ~ 3/4" Wide) Prep the Bore for Polishing. * Polishing. Using Jewelers Rouge's No.-5 & No.-6 and a Dremel Polishing Wheel ... Polish the Bore to a Mirror Finish.