Your Question
Motorcycle: stiff chain links - able to repair?
The Answer
NO, this is not really repairable. Throw it away.
The reason why I say this is that the pins inside the castors or rollers are more than likely rusted together inside the chain. The danger isn't the rust, it's highly unlikely to be so bad as to weaken the chain extraordinarily, it's a safety issue.
The chain rides up on the sprockets at incredible speeds. When they break they are extremely dangerous. Have you seen a tire explode in NASCAR during a race. All that damage is created by rubber, nylon and thin cables. Imagine your chain coming off and the damage it would do to you or a passenger. I've seen chains go through motors.
A sticking link chain will bind
A sticking link chain has a higher chance of breaking
Sticking link chains will come off sprockets...and destroy swingarms and possible lock the engine up. From 5,000 RPM's to zero in a snap. Not good for engines.
Sticking link chains will destroy sprockets in weeks instead of years. They land incorrectly on the sprocket and don't distribute the power delivery on every link. Some don't touch the sprocket. This increases wear dramatically.
Sticking link chains show no mercy. When they break they destroy things. When they hop off sprockets (this would be my greatest worry) they gouge up swingarms and lockup motors and even destroy them from time to time by getting sucket into the power side on the motor and getting bunched up thereby punching a hole in the motor.