At idle left cyl misfires. Remove right plug wire at idle and bike dies. hold idle up and remove right plug wire and bike stays running. runs good on the road as long as you are in 2nd gear. Has good fire all time. swaped plugs and no different. I think it is lean on left cyl. bike only has 2100 miles on it. it is a 1983 cm450e. i could not find it in drop down list.

Is that what you are reading as the code ? To verify this fault have the engine running, with an insulated pair of long nose pliers and remove plug wire from number one spark plug. Let me know if the engine pitch changes.

Do the following

Here are the most common causes of idle surge, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

Bad stick coil

CODE P1300 IS MISFIRE DETECTED FUEL PROBLEM. WHICH MEAN 3 FUEL INJECTOR IS CLOGGED UP.HAVE FUEL INJECTORS CLEAN AND CHANGE FUEL FILTER.

Has anyone found the problem? My 2003 has #3 cyclinder misfire and I have replaced the plugs and wires. It runs rough at idle but smooths out at highway speed. Anyone have any knowledge on this? This sounds like a common problem.

wrong plugs possibly installed, use standard range plugs i use NGK#8 and a lower octane for awhile see if that clears it up.

Drain the carburetors. There should be a screw on the lower side of each CARB float bowl. Remove the screw then replace it after the fuel drains. Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, (not all bikes have a water trap bowl). Install new stock NGK spark plugs.

Remove the CARBS from the bike.
FOR EACH CARB > Remove the float bowl and clean the entire CARB with a spray CARB cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the CARB. Remove the idle screw and the air screw on the outside throat of the CARB and spray into the screw holes as well.
< < READ CLOSELY > >
Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Put the rest of the CARB back together, clean the air filter and install the CARB. Install an in-line fuel filter. Let the float bowl fill then start the engine.

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 the LEFT 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.

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 the idle screw on each CARB EXACTLY ONE HALF 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 balanced and synchronized your CARBS This should fix the problem. One last and VERY IMPORTANT thing, Have a fire extinguisher handy and ready for use any time you work on or with he CARBS.

Please rate this solution. Thanks throttlejock!

If the bike runs then Top Dead Center (TDC) is not an issue. But to check piston stroke position, Remove the valve cap cover on the intake of the front cylinder. Remove both the spark plugs. Rotate the crank shaft untill the rocker arm starts to move. The piston is now starting down on the intake stroke. Rotate the crank further and the rocker arm moves in the opposite direction. The piston is now going upward on the compression stroke. Look at the marks on the flywheel. Rotate the crank untill the TDC mark lines up with the timing index mark. The front piston is now at TDC.

If your model has carbs then the backfire fix requires you to syncronize and balance the carbs.
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 the LEFT 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 balanced and synchronized your carbs.

Please rate this solution. Thanks sgtswampdonk!

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 the LEFT 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.

Please rate this solution. Thanks!

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 the LEFT 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.

PLEASE RATE THIS SOLUTION. Thanks!