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Ski Doctor
Ski Doctor, powersports repair specialist
Category: Motorcycle
Satisfied Customers: 818
Experience:  over a decade of double time experience, excellent electrical and mechanical diagnosis capabilties
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i have a 1982 750 kawasaki spectre. i rebuilt carbs and now

Customer Question

i have a 1982 750 kawasaki spectre. i rebuilt carbs and now it is running way too lean. also flames out when i give it gas. do i have to have the air cleaners hooked up for it to rev up when i give it gas
Submitted: 7 years ago.
Category: Motorcycle
Expert:  Ski Doctor replied 7 years ago.

yes...these bikes were set up lean from factory, and without the air cleaner hooked up, it is even leaner. to properly adjust the air/fuel screws you have to have the intake system hooked up. without the air intake tract, the bike will probably only rev up about 1/2 way.

the tops of the carbs have fuel screws that you adjust to fine tune the throttle response and bottom end. start at about 1.5 turns out each, and slowly turn them out 1/2 turn at a time and listen to the idle. as you turn out the fuel screwm it will add more fuel, and richen the fuel mixture. as the engine gets more fuel, the idle will go up because the bike is running a little better. so turn each screw out 1/2 turn, and as the idle goes up, adjust it back to proper speed. repeat this fuel screw method untill the idle doesnt go up anymore. after you have adjusted them and the idle wont go up, turn each screw back in 3/4 turn to lean it just a little.

if you get to 4 turns out, and the idle still goes up, then you need to rejet the pilot jets(smaller jets) inside the carbs.

good luck!

Customer: replied 7 years ago.

IT HAS KEIHIN CARBS. I WAS TOLD THE SCREW CONTROLS THE AIR INTAKE. TURN THE SCREW OUT MORE AIR, LESS FUEL, TURN THE SCREW IN LESS AIR MORE FUEL. IS THIS TRUE, AND IF SO , HOW MANY TIMES SHOULD I TURN THE SCREW OUT TO BEGIN, AND THEN SHOULD I TURN SCREW IN TO INCREASE FUEL

Expert:  Ski Doctor replied 7 years ago.

here is how to tell if the screw is air or fuel:imagine cutting the carbs in half right down the middle so one half is on the engine, and the other half is on the air intake. if the screw is on the engine side of the carbs(either top or bottom) then it is a fuel screw. turn it out, and the cabrs allow more fuel to flow which will make the mixture richer.

if the screw is on the intake side of the carbs, then it is an air screw. when the screw is turned out, more air will enter the pilot circuit leaning the mixture out.

this model has fuel screws, so turning then screw out will richen the mixture. if you get to 4 turns and it is still too lean then you will need to rejet.

make sure you have the airbox and air filter installed and the system is air tight you when you adjust the fuel screw, you are being accurate.

start at 1.5 turns out, and slowly turn the screws out 1/2 turn at a time. you will hear the idle go up, and when it does, reset it back to the right idle speed. continue to turn the fuel screws out 1/2 turn at a time untill the idle does not go up anymore. after you are done turning the screws out(the idle stops going up) then turn each fuel screw BACK IN about 3/4 turn.

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Customer: replied 7 years ago.
THANKS, XXXXX XXXXX I AM FINALLY GETTING SOME RELIABLE INFORMATION. THANKS AGAIN
Expert:  Ski Doctor replied 7 years ago.
ask any questions you have an we will try our best to help