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Discussion Starter #1
HELLO, EVERYONE IM NEW TO THE WHOLE THING ABOUT THIS KFX 450R, IS THE FIRST TIME I HAVE A FULL INJECTION MACHINE AND NOW I HAVE A PROBLEM WITH IT THE MACHINE WILL START AND IDLE BUT WHEN I GIVE IT GAS START BACKFIRING AND THE ACCELERATION IS BAD IF I GIVE HALF WAY THROTTLE THE BACKFIRE IS MORE AND IT SHUT OFF

THIS WHAT I HAVE DONE:

CHECK AIR INTAKE FOR HOLES
CLEANED AIR INTAKE
AIR FILTER IS CLEAN
CLEANED THROTTLE BODY
PUT A NEW SPARK (CPR8EB-9)

THE GAS I'M USING IS 93 FREE ETHANOL

I CAN'T FIND ATV MECHANIC HERE IN FORT BRAGG
 

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Welcome to the Forum...!!!

Was it running fine and all of a sudden your symptoms appeared...???

Is your motor all stock or has upgrades...list mods...?

Make sure the battery is fully charged 12.8v standard..

Does your (far left) F.I light remain on or flashing when starting/idling or turns off after 3 seconds...??

Make sure the throttle cable has a little slack in it to close the butterfly to idle position or the Throttle positioning sensor/TPS can bounce out of range...

Check the TPS voltage to be in range...see picture
 

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Discussion Starter #3
It was running fine i put it in my garage and then after a week I started and start doing it

motor is all stock I do have an aftermarket Muffler

light turns off after 3 seconds

I will check tps tomorrow

also battery is 12.3v
 

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It's recommended to put the battery on a battery charger before riding...12.3v is low & questionable...

Ok..causes for your symptom to check

Low battery voltage...check alternator output see pic
Out of range TPS...see pic
fuel pump strainer is clogged/dirty..thread on it if needed How to clean fuel pump
Faulty water temp sensor... see pic
low compression.? Cylinder Compression Service Range 49.0∼ 81.8 psi) @900 r/min (rpm)
Valves needing adjusting... ?
Valve Clearance: between cam and valve lifter
Standard:
Exhaust 0.17 ∼ 0.22 mm (0.0067 ∼ 0.0087 in.)
Inlet 0.10 ∼ 0.15 mm (0.0039 ∼ 0.0059 in.)
If the valve clearance is not within the specified range,
adjust it.
 

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