1985 Force 85hp idle smoke and noisy.

The compression is 120 on all cylinders, but reading the service manual, I just found out the throttle should have been at WOT when doing compression test, so it is probably higher. Specs say 145 to 165, so the motor is low, but even.

Motor starts with just a bump of the starter, idles smooth, and it appears that the CDI and Coils were recently replaced by the previous owner.

The problems with it are:

1) smokey while idling along at no wake speeds. Use Walmart TCW3 oil at a 50:1 mix. I have removed the two hoses and their fittings on the intake manifold that return unused gas and checked for clogs, stuck check balls, etc. Both the fittings have no check balls. Both the fittings are clear at either end of both hoses. Both hoses are clear and can be blown through easily. Spark plugs show little to no carbon buildup. What else could be causing smokey idle and off idle operation?

2) motor makes a kind of "rattly" noise as it winds up under WOT. Its running smooth, but it sure sounds like its going to let a rod loose at any moment. Been doing this since I owned it, but it just doesn't sound right, (or as smooth as my 40 hp Johnson twin). Sound OK at cruising speeds at about 1/2 or 3/4 throttle. Are these just noisy motors? Or does this indicate worn main bearings or the like?

Re: 1985 Force 85hp idle smoke and noisy.

Well, the manual recommends WOT to check compression but in reality, it doesn't make much of a real difference. Since the engine has ports that are both open at the bottom of the stroke, the cylinder is at atmospheric pressure whether or not the throttle is open. The only difference is that with the throttle open, the engine will crank a little faster because of less vacuum and crankcase resistance.

Even at 50 -1, you still will experience smoke at idle. It is simply a fact of life. The idle relief vents are above the water and at idle, some exhaust is exiting there, and you are burning oil. Wind blows it back into the boat to annoy you.

Rattly noise? Difficult to define. BUT: Pre-ignition and detonation sound like a rattle. Double check the timing to be sure it is not advanced past 30 degrees BTDC at WOT, and double check your low speed needles to be sure they are at 3/4 turn out or more. Too far in and the engin runs lean, may detonate and may have a rattling sound.

Re: 1985 Force 85hp idle smoke and noisy.

Thanks for the info, Frank. Will do a sea foam decarb after vacation. I did spray carb cleaner in each cylinder and turned over by hand, then left to soak overnight. Today it sounded better, not as rattly. So hopefully a good decarb will help, and maybe get the compression up if the rings are stuck.

Re: 1985 Force 85hp idle smoke and noisy.

Mark42 said:

1) smokey while idling along at no wake speeds.

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... nature of my smokey joe as well. i would not worry a whole lot over it long as you keep her maintained like you do. i love the smell of two stroke in the morning!

Re: 1985 Force 85hp idle smoke and noisy.

Frank Acampora said:

Well, the manual recommends WOT to check compression but in reality, it doesn't make much of a real difference. Since the engine has ports that are both open at the bottom of the stroke, the cylinder is at atmospheric pressure whether or not the throttle is open. The only difference is that with the throttle open, the engine will crank a little faster because of less vacuum and crankcase resistance.

Even at 50 -1, you still will experience smoke at idle. It is simply a fact of life. The idle relief vents are above the water and at idle, some exhaust is exiting there, and you are burning oil. Wind blows it back into the boat to annoy you.

Rattly noise? Difficult to define. BUT: Pre-ignition and detonation sound like a rattle. Double check the timing to be sure it is not advanced past 30 degrees BTDC at WOT, and double check your low speed needles to be sure they are at 3/4 turn out or more. Too far in and the engin runs lean, may detonate and may have a rattling sound.

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I agree, if you dont like the smoke get a 4 stroke. Also I read somewhere that if you retard the timing to 28 degrees you will get better performance and most likely less backfire and shaking at idle. I will try this soon.

Re: 1985 Force 85hp idle smoke and noisy.

jason32038 said:

I agree, if you dont like the smoke get a 4 stroke. Also I read somewhere that if you retard the timing to 28 degrees you will get better performance and most likely less backfire and shaking at idle. I will try this soon.

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I also have a Evinrude 40hp two stroke, and it doesn't smoke like this Force does. Just seems excessive.

I

Re: 1985 Force 85hp idle smoke and noisy.

The older (80's era) Forces do smoke a bit. Having it tuned as properly as possible will help. Seafoaming it will help A LOT also. Especially if it's never been done before.