1990 20 hp throttle adjustment

[wildfire]

I have a 1990 20 hp that doesn't seem like it is performing much different than my 9.9 on the same boat. The motor is a tiller and when I look at the throttle cable, where it connects to the rod leading to the carb, it appears there is quite a bit adjustment that could be done by moving the jam nut. Could this have been adjusted down by the previous owner to limit speed? If I open it up more are there any negatives?

Thanks

 

[racerone]

At idle there should be about 3/16" gap between that stop.-----Many folks adjust that because it " looks wrong " when it is correct.-------Check and see if you are running on both cylinders.---Check compression and check for strong spark on both leads.

 

[wildfire]

Thanks. Currently there is about 3/4" between stop and the adjustable nut when at idle. The throttle body on carb only moves about half of its total range of motion.