ktmbmk66

I have a 92' polaris rxl EFI 650 and I am hoping some RXL veterans can give me a hand with this one, here is the specs. All stock, with a fresh engine rebuild. Excellent compression, all castings machined (stock c.r recut), new crank, seals, ect. Clutches have been rebuilt, alinged and belt deflection adjusted. Fresh NGK BR9EIX's installed with excellent spark. Throttle bodies are sync'd and idle at 2200 rpm. Here is the problem- Cold engine, two pulls and it fires up, high idles great, warms up and idles down, has full power and responsiveness for 15-20 mins of ride time. Then quite consistantly (every ride attempt) the engine will have basically no 0-25% throttle response (will die if under 1/4 throt.) and when throttle is applied +25% the engine surges and back fires with short bursts of power. The sled is able to continue back to shop under its own power but once it cools down it again runs normally. I am getting a crank case temp code on ecm. and i replaced sensor and checked wire (which was on good). If the engine was carb i would have checked stator and cdi. But im am unsure if this is a ignition system problem or a efi lean/rich issue. Before i tear into it id like to get some EFI experts opinions! Thanks! Jeremy.

farmin_on_snow

i have a2002 sks that im having the same issues itsound s like. mine is carbed thouigh and ive done everything on the fuel side and nothing. tryed a cdi box same issue new pluys wires and caps still pops and mine gets worse as i ride and sled gets good and warmd up. next i thimnk im gonna try swapping coil.

Snowweasel

U said the engine has been machined? What was machined and how much removed?


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2003 arctic cat zl550 (looking to sell)

farmin_on_snow

i made a tps checker and checked mine and its way off spec one volt off and im not sure why i think the carb sync rod is bent but im not sure