Why is your 1976 Suzuki 125 revving up when you crank it?

Answer 1

Your throttle cable is probably dirty and stuck up, or the cylinder in the carburetor, which holds the carb needle, is stuck in the open throttle position (UP)- this could be due to a long overdue cleaning and maintenance routine. It is also ONE OF THE MOST DANGEROUS THINGS TO HAPPEN TO A MOTORCYCLE RUNNING AT FULL SPEED: a STUCK THROTTLE.

The best remedy for this situation is to check both cable and carb. You will have to unscrew the top of the carb where the throttle cable enters the carburetor barrel. Pull the cable out and check if the spring still works. If the spring is still original (1976) it WILL most probably be broken and won't return the cylinder DOWN to the closed throttle position. Replace the spring. If it is still whole, shiny, and good- spray it with Carb Cleaner.

Actuate your throttle by twisting the grip- check the return action on the spring. If it goes back, your cable is good. If not, put the small red hose that comes with your Carb Cleaner spray into the spray nozzle and spray a little INTO the cable's housing to clean the cable. Twist the throttle grip while the cleaner is still wet to get the cleaner into the cable. If this loosens the cable, then your problem is found. Spray a bit more cleaner into the cable, (best done if you REMOVE THE WHOLE CABLE AND SPRAY INTO IT FROM BOTH ENDS AND PULL THE CABLE IN AND OUT).

Then spray WHITE SILICON LUBRICANT into the cable from both ends.

Assemble your carb and cable. Start your engine as you normally would.

If all else fails, replace the throttle cable.