97' 40HP 2-cycle one carb

[Relaxation]

Having issues with RPM being too high in idle and topping out before max throttle.

I've tried adjusting the timing screw, but no change or very little. I'm hitting around 2k rpm sitting in idle, when according to the manual it should be 700-800. My RPM meter tops out at 8k, which I'm hitting at half throttle.

I just replaced the spark plugs, and the gas in the tank is 50/50 new gas and gas left over from last year.

Any suggestions would be appreciated.

Below are a few youtube videos of the outboard in question.



https://www.youtube.com/watch?v=06efTUWhi2A

https://www.youtube.com/watch?v=wmRgCHkb3AQ

 

[roscoe]

First of all, welcome to iboats.

Second, stop revving the engine with no back pressure ( out of the water ) on the exhaust.
It doesn't show anything meaningful, and it won't last long.

Third, I suspect your tach is way off.
Idle did not seem to be 2000 rpm, but hard to tell since you were revving it.
The engine would also likely not survive if it was turning 8000+ rpm.

Hopefully you have access to a decent manual that details, throttle cable adjustment, carb settings, and timing procedure.

What is your initial carb setting?

 

[jerryjerry05]

First off the "timing screw " is for timing and can cause problems when you "adjust"

There is a screw with a spring wrapped around it on the side of the carb.
This isn't an idle screw either.
This is an air/fuel mix screw. This is how you set the idle for smooth running.

The idle is set by the linkage,towershaft on the side of the motor.

The first 5 posts in this forum has a lot of info you might need?? READ!!

The pic shows a generic towershaft, yours is something like this.
The screw and lock nut is where you adjust the idle.
Get a "factory manual" if possible.

 

[Relaxation]

Thanks for the help, I was adjusting the air/fuel mixture screw. Ordered a technician manual off e-bay as that's all I could find https://www.ebay.com/itm/202776042746 I've been using a seloc which isn't that great. Your images/links didn't come through Jerry. I've also ordered a tach to hopefully get a better reading. https://www.amazon.com/gp/product/B01CPCO9X4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1