The Exhaust Valve cables control the valve which varies exhaust back pressure. This allows greater power throughout the rpm range. Too loose cables can impair the proper operation of the valve. Too tight cables can prevent the servo motor from operating.
Remove the Exhaust valve pulley cover. This is located on the left side of the bike down low just in front of the centerstand. Remove the bottom and left bolts with an 8mm socket head, the top bolt just needs to be loosened. The cover then slips off.
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Underneath the cover is the Exhaust Valve pulley. It is controlled by two cables. The free play in each cable should not exceed 1.5 mm (0.06 in.). That 1.5 mm is free slack, movement without any pressure at all, not as far as you can push it. Mine were very loose. The 'fork' in the pulley should line up over the hole as shown. If it does not then it may be 30 degrees or more advanced. Turn the ignition ON then OFF. The pulley fork should now be aligned over the hole.
If the pulley is not lined up over the hole then the cables are very likely improperly adjusted beyond the tension adjustment. You should loosen both cables until you can manually rotate the pulley until it lines up over the hole (see below how to loosen the cables.) You should do the ignition ON then OFF sequence again to make sure the servo motor is properly zeroed. Then proceed with the tension adjustment.
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Prepare the pulley for cable adjustment by jamming the pulley in place. Use a 4 mm or 9/64 in. hex wrench as shown. For me 4 mm was a bit too big, 9/64 in. was just right.
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On the other (right) side of the bike just under the tank and above the carb top are the two Exhaust Valve cables with adjusting nuts. Loosen the lock nuts. Tighten the cables up to the point where there is no free play at all. Turn the adjusting nuts clockwise (more thread showing) to tighten the cables, counterclockwise (less thread showing) to loosen. The service manual contradicts this direction but that's just a matter of which side of the nuts you are looking from. The important thing is the amount of thread showing. On my bike, the cable with the silver colored threads was for the top cable as seen on the pulley, the cable with the black threads was for the bottom cable as seen on the pulley. I was able to actually feel when the cables had no more play as I turned the adjusting nuts one way then the other. The resistance to turning the adjustment nut increases a lot at the very point where all the slack is taken up. Lastly, loosen each adjusting nut one-half turn. This should produce just the right amount of free play. Verify this by checking the cables on the pulley.
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Tighten the lock nuts.
Replace the Exhaust Valve valve pulley cover (10Nm, 7.2 lb-ft) (I just tightened the bolts until snug).
Next time you start the bike, make sure you don't get the 7000 rpm error code on the tach. If you do, it likely means that the servo motor is unable to actuate the exhaust valve because the cables are too tight. The bike can be ridden like this because the electronics will cut off power to the servo motor so it doesn't burn out. Loosening the cables should make that error code go away.
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Last Updated: 04-28-2003
Copyright © 2001-03, Patrick Glenn, All Rights Reserved.
The information presented here reflects solely my personal experience with my motorcycle and is presented
for entertainment purposes only. No information presented here is to be relied upon for issues of rider safety
nor to replace the services of a qualified service technician.
Any attempts to follow or duplicate any of these procedures are done so completely at your own risk.
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or consequential damages that may arise from any information presented herein.
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