2-stroke smoke

[Arimaguy]

Does anyone know why my 2stroke 6hp johnson smokes so much? its seems to run ok but there is a constant cloud around my boat. Also i get real bad viberations when running dead slow. Im new to this boating thing and would love some help. The gas was in the boat when i bought it, thats the only thing i can think might be wrong. I replaced the plugs and lower unit oil just the other day.

[Drewp]

I assume you're mixing gas if it's an older two stroke. Ususally if it's smoking a lot that means that your, "running rich," i.e., you've got too much oil in mixed in with the gas.

[gpc]

Was the tank full? If it was only a partially filled tank then over the winter condensation will occur if the tank is only half full. Or maybe they wasnt a fuel stabilizer added for storage during the winter and thats what made the gas bad. In any case, it sounds like the gas you have is old. Or what Drewp said, you have the wrong ratio of gas to oil going on.

For the shaking when you are just above idle, that happened to me when I bent the prop on my motor. Lets hope its not that because those things arnt cheap. Especially if you have a stainless prop

[Rollin with Rolland]

i would definitely agree. number one change gas and mix it right. vibration...some smaller motors will do that, but it shouldn't be excessive, like gpc said, bent prop would do it....put it in neutral and see if it still vibrates "real bad".....

[Gisteppo]

How old is the engine?

What trauma has it sustained in its life?

What ratio of fuel/oil is reccomended for that particular engine? Was it mixed to that ratio?

What is the correct spark plug gap and are the plugs gapped to the correct spec?

This is a good baseline to start. From these we can ascertain the problem more accurately.

E

[Arimaguy]

Thanks for all the help guys. The prop looks good no dings or bends. to answer all your questions: the motor is a 1986, no major trama that i know of but the previous owner only worked on it when it broke! The gas ratio is 100/1 and i am just going to replace the gas from the previous owner because the boat was stored for the last two years and it was not a full tank. I replaced the pulgs with the correct gap of .030. thanks again

[Gisteppo]

Definitely do a rule-out with the new fuel. Generally 100:1 motors are pretty smoke-free (its the old 40:1 motors that are good mosquito protection).

If the motor still smokes excessively, it is probably at a point where the rings have worn beyond spec and you are getting some blowby from the crankcases. This is extra raw fuel and oil creeping up past the rings, and it creates a rich mixture. Depending on the life of the motor, they can run like this for eeons, but with less power and economy than original. A decent shop will do a quick hone, drop some new pistons/rings/pins in the motor, and you will be off and running in a basically new engine for a few hundred bucks.

E

[Marc Martyn]

I had a Johnson 8 hp about that same vintage. It was almost new and it did shake quite a bit. It also seemed to load up fairly easy while I was trolling. I would periodically run up the motor to burn out the oil. I ran it for a few years and then bought a Merc 9.9 The Merc idled down smoother than the Johnson. I think that the vibration is common in Johnsons. Check with an outboard dealer on the mixture. Also, check to see if you have the correct heat range plug in it.

[Gisteppo]

Vibration is more common in single cylinder engines, and most motors 9.9 and above are twins. This makes them much smoother.

E

[Fisherman_max]

its kinda a dumb thing to do but i run rich fuel through my YZ250 partly because i like the smell of the racing fuel. dont ask why i just do.

[trout slayer]

bean oil is good to just dont stand to close to the exaust. lmao

[hewesfisher]

Vibration is more common in single cylinder engines, and most motors 9.9 and above are twins. This makes them much smoother.

Right on with that. The single cylinder motors are thumpers, my 6hp Merc is that way and it's the only thing I don't like about it. I've found that 8hp and up are all 2 cylinders and they do run much, much smoother, and quieter, than a single.

I'd replace my 6hp with and 8hp to get rid of the single cylinder thump, but it runs great and weighs 30lbs less than the 8hp, plus it's already paid for, so it stays!

[Anglinarcher]

One other thing, get with someone that has more boating experience. Let someone else judge how much smoke you are getting.

I have an almost new 90 horse Merc, oil injected 2 cycle. Compared to a 4 cycle, it is a smoke pot. Nevertheless, it is running correctly.

If the dealer would have let me trade the 2 cycle for a 4 cycle when I bought the boat new, I would have, but............... the boat had set at the store for a year and they did not want an older motor they had to move.

It is quite possible that the amount of smoke you are seeing is normal. I tell my friends that I like the smoke, it makes me remember how much money I am putting into the engine every time I go fishing.

[Arimaguy]

New gas seemed to take care of some of the smoke! thanks for the help guys. I still think im gonna have a shop look at it just to be sure its all cool. I think the vibration was comming from the old rock hard fuel line pushing the old metal tank around when i turned so i replaced everything and no more vibration. believe it or not this little 1985 6hp is a 2 cyclinder and each one has its own coil! Seems ahead of its time to me but its working great now. Thanks again