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Cleaned carbs, new spark plugs, changed oil/filter, air filter, new throttle cable on 1982 XJ650J. When throttle set to idle correctly, engine revs badly when handle bar turned to the right. Any thoughts anyone?
Wrong size throttle cable or misadjustment. At the handlebars, I've seen some set that acceleration causes a pull of the cable, I've also seen bikes set to push the cable. Confirm this is set correctly, and that your mechanic used the correct legnth of cable.
Being an older bike, maybe a wire from the hand controls is shorting out, even in side the handle grip switches, or going down the neck under the tank. normaly a throttle cable problem would cause the rpms to go up when turning the handle bar, thats why im suspecting a short
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You don't tell the make but check your air filter and make sure it is clean or replace it. Your carb float may not be set right as well some mowers has the choke throttle setting when you shove the throttle as fast as the engine will rev the choke will be on.. Those types of engines you have to let off on the throttle a little bit so it does not choke. Is the engine old enough that the rings are bad and letting oil into the carb. If so that will make the plug dirty as well.Just to give you ideas what could be wrong.
My money is on a partial blockage of the main jet or the passageway to it. You're having to force it to run through the idle jet by fully choking the incoming air. There's not enough gas coming in with the choke open to allow it to run.
I'm thiniking total carb disassembly, carb cleaner and an air compressor combined with a ton of patience will take care of the issue.
Try balancing ans syncronising the carbs. BALANCE THE CARBS Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place. Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove theLEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place. Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed.
SYNCHRONIZE THE CARBS Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb. With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.
Turn off the gas and remove the water trap bowl at the bottom of the petcock, (gas valve). Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ). Get a set of the stock NGK spark plugs your bike came with. Check for spark on each cylinder before installing the plugs. Now go to the idle and air screws on the outside of each of the carbs. IMPORTANT > > GENTLY turn both screws all the way in until they LIGHTLY seat. Now turn the screws EXACTLY one and one half turns outward. SYNCHRONIZE THE CARBS Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb. With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides. BALANCE THE CARBS Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place. Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove theLEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place. Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed. Congratulations, you have just synchronized and balanced your carbs.
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