Johnson Seahorse outboard. Acceleration Deceleration problems

[yorkie gull]

Can any one help.
I have purchased a revamped 1982 model seahorse 2 stroke outboard. Problem is that the engine wont decelerate after increasing the speed over half way without hitting the kill switch. On restart the engine behaves normaly, untill increasing the speed to the over half way point again.We have checked the carb and diaphram and found them to to be running normally. Can any one give some idea on what could be the problem.
yorkie gull

 

[Daviet]

Re: Johnson Seahorse outboard. Acceleration Deceleration problems

Could you post your model number so we can look at your exact engine?