throttle position on 9.9hp johnson

[Newyota]

Since I am the third owner I have no idea what was done to my motor i have a question.Can someone tell me that has a 9.9 like mine(1988) or similar vintage when the throttle is turned and looking inside the engine compartment where the small roller for the throttle plate that rides up along on the black plastic piece to open the throttle stops at full throttle?Hefully you understand ?Not too difficult.I refernce it to the adjustment screw on the end of the black plastic piece.Maybe a pict. or measure it for me.I have know idea how much this engine should rev. and not shore if the throttle linkage is adjusted right..thanks

 

[AlTn]

Re: throttle position on 9.9hp johnson

can't directly answer your question, but here's the deal..at wot, in gear, the throttle plate should be perfectly horizontal in the carb throat< neither under nor over rotated >...can you see the plate with an inspection mirror or feel it with your finger and determine this?..if not, remove the carb that looking at the throttle plate from the rear of the carb, when it is horizontal in the throat, mark the carb body when the position of the roll pin on the throttle plate shaft is where you want it....you'll then have your alignment marks

 

[Newyota]

Re: throttle position on 9.9hp johnson

ok-thanks.Well when i went to the river yesterday I was trying to get it up to full speed as I had done at home with the muff and last week one time on the water.Throttle did not seem to want to move any further these times, but this time I gave it one more hard turn and low and behold the engine took off like a rocket.Almost felt like somethimng kinda popped free.Wonder if the cable was alittle bound up inside the cable housing?Anyway I topped out at 23mph on my GPS with my 14' boat.Got alittle scary due to choppy water.I may have a 15hp carb. on this engine?Was looking at a video on youtube that showed the Venturi size difference and after removing the choke pull and the grommet for it I shined a light in there.It was not the best way vs removing the carb., but the opening looked like the opening for the 15?thanks

 

[gozierdt]

Re: throttle position on 9.9hp johnson

Someone could easily have put a 15 hp carb on your engine. If you look at "Leeroy's Ramblings"
you'll find a ton of information on these engines. In particular, in this article

http://www.leeroysramblings.com/Johnson%209.9_15.htm

you'll see pictures of the differences between 9.9 and 15 hp carb throat size. With that
as a reference, it's pretty easy to tell which one you have. There were two other
differences between these two motors, one is the exhaust housings, and the other is
a spacer added to the reed valves to allow them to open a little more. Leeroy talks
about both of these changes also. But the carb is the big one.