Johnson 40hp 1995 overheating and rough idle?

[Ricky_rich]

I’m having two problems here with this motor, think they might be connected.

Problem 1. I cannot get the engine to idle properly, have done the link and sync process. Cleaned the carburetors and make sure there getting fuel. Spark is good on both cylinders. When giving throttle there isn’t really much power there. 40hp kind of feels like 8hp.

Problem 2. Engine overheats quite fast. I have a good flow through the tell tail. And I have opened and checked the thermostat when engine is running hot, and it’s fully open. One thing I noticed is that right when the engine starts, there is some smoke coming from the tell tail. Then when the water comes, and I cannot see the smoke, might be there though. If I run the engine without the thermostat, it’s not overheating, but runs like crap.

 

[brodmann]

A lean condition will cause both of those issues. When you "cleaned the carbs", did you soak it overnight and clean out the jets? Did you take it completely apart and did you set the float levels per specs? I've attached a link to a video where the guys shows how to clean the jets. Low speed and high speed. This is a must.

Good luck and let us know how it goes. Obviously, you could have a timing issue or a spark issue, but a lean condition will cause both poor running and an overheat even when water pump seems fine and thermostats seem to be working correctly. Also, on a 2 stroke that doesn't have an oiling system and you actually mix the gas yourself, if your carb is clogged and gas isn't getting through, then oil isn't getting through either. That causes catastrophic issues in not time at all.