i have a Kawasaki prairie 700 i just replaced the spark plugs, inline fuel filter, changed oil, added super coolant mix with 50/50 coolant, dissasembled carbs and cleaned them and adjusted them to 2 1/4 turns out. it runs great overall but around 35-42 mph i hear a flat tone for a second or two at full throttle i can hit 59-62 mph with lift kit, winch and ricochet skidplates, plus big *** exicutioner tire but i dont think is running perfect anyone know why at 35-42 mph i have a slight power and acceleration drop? i also have k/n filter and hmf exhaust system.

 

I'd be inclined to try 1 or 2 size bigger main jets. Do a couple plug chops, before and after. Should show a nice tan color on the electrodes. V-Twins usually run 1 size richer in the carb on the front cylinder. You might like a DynoJet kit, the adjustable needles are great for mid range tuning. Realize, larger tires will read slower speed on the speedo, and if your ATV has a clutch kit, it may run faster or slower. My AC 700 would run 70+, then I did a Hypershift kit, tuned for acceleration, now only 60, but it rips to get there. You should try to ride another one, it could just be normal.

 

i used to have a moose power pack idk where it went but didnt notice any difference with it on i doo have over sized tires and a high range clutch spring with hmp exhaust and i should have moose jet kit but i think the shop who was supposed to put them in just use regular jets cause the order got messed up and i need my atv for a trip and they said they had some moose jets laying around so they installed those but i had constant issues after their work untill i took the time to tear it down and rebuild it i also have the higher heat cat spark plugs what ever that means. any way i have been doing much high speed driving lately so haven'y bothered today im installing a second battery in the storage box cause my winch draws too much power after im finshed i may do so carb adjusting

 

Try a Dynojet kit. I've used em on older Arctic Cats. The adjustable jet needle is nice. Or , if you know the jet size for the main jet, you can order a couple fatter ones from <jetsrus.com> Here is a chart, as Keihin, Mikuni and Dynojet numbers are a bit different. Why they didn't standardize, who knows?