83 85 HP force outboard idle and exhaust question

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

These boats were designed for ski boats. They figured that the boat would be operating most of its life at WOT. Therefore, it was designed to get the most at that speed and part of the design was surface gap plugs. These plugs operate most efficiently at WOT. They are rather bad at idle and trolling speeds. You will always get some carbon build up on them.

Most of us just clean them once a month and leave it at that. If you play with the timing or lean the carbs, you chance burning a hole in your piston.

It doesn't take much to pull them periodically and clean with scotch brite pads and carb cleaner.

John

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

Job done then, thank you very much John.

 

[sho3boater]

Re: 83 85 HP force outboard idle and exhaust question

Black plugs indicate a rich mixture. But to get a true read on plugs you would run it WOT for some distance at full operating temps, then shut it down as quickly as you safely can in the water...and color read the plugs then. They should be a tan color not too light or it is too lean. If your carbs are working right it should not be an issue as the jets can't change....unless someone changed them. Possible but unlikely. Water in the engine or fuel system issues could affect plug color of course.

 

[sho3boater]

Re: 83 85 HP force outboard idle and exhaust question

I had a merc inline 6 with surface plugs and they stayed clean all the time, like new clean though I didn't put a ton of hours on the boat. I did run it hard much of the time. Every time I looked at them they were wet and like new.

 

[birdgod]

Re: 83 85 HP force outboard idle and exhaust question

hi, I noticed above that your getting 43 mph out of your boat and I was wondering what pitch prop you had and what your maximum rpm was. I have a 89 17' trophy center console with the Force 85 and ive had a problem with its speed. After having the carbs syncd, timing set, decarbing it, playing with different pitch props and other stuff (120 psi compression, good spark, 93 octane)I can only get 33 mph at a maximum of 4000 rpm... those figures are at ideal conditions usually i get 30 mph. Anything anyone has to say would be great.

thanks,
-George

I was going to ask that question. I have a 1989 spectrum with force 85hp. The top speed I get is 30mph by GPS.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

I have a clean Bayliner 1600 with an '85 85hp Force engine. My compression is 155 for all three cylinders and I use a 19 pitch prop which turns at 5500rpm at WOT.

I also have trim tabs and my boat is not waterlogged. Many older boats have waterlogged foam and wood and the weight alone keeps them from making high speed at WOT.

Also, the see state must be perfect for me to get 43gps. That doesn't happen too often in the Chesapeake.

George, do you work on your own boat or did a boatyard mechanic do your work for you? My reason for asking is that most mechanics in boatyards don't know Force engines and do more harm than good. You have a problem if you are only getting 4000rpm. Your compression is low and can probably be brought up by a couple of good decarb treatments. I also suggest that a Trophy is much heavier than my Bayliner.

John

 

[collegefund]

Re: 83 85 HP force outboard idle and exhaust question

Well its been quite a while now but im going to write back to see if any of you are still here. Its boating season again and im ready to get back in the water!

So in response to the last question, yes ive done all the work myself and had it checked over by a local boat repair shop. Heres an update: What ended up happening is I dropped from the factory equipped 17 pitch cupped prop to another aluminum 15 pitch uncupped prop for a grand total of 4200 rpm @ 30-32 mph. I just advanced the timing on the water to an unknown setting lol, I know thats not good but I do run premium gas and good oil always and it didnt seem to hurt it after all the times I took it out. My next step is going to be changing the lower end oil and repaint the bottom as it is very rough from whoever painted it before. I hope* to get it to around 40 by making the bottom very smooth and using VC Offshore racing bottom paint.

Any questions/comments/advice will be very much appreciated

-George

 

[erikpn]

Re: 83 85 HP force outboard idle and exhaust question

Steam in the 'No Wake' zone is an indicatio of low water pump pressure and flow.

When was the water pump services last?

Besides changing the impeller, take a very close look at the cup and lower plate to see if they are worn to the point that they may not seal well with the new impeller. A water pump rebuilt kit really isn't that much when you compare it to the possible cost of a rebuild due to a serious overheat.

ALWAYS run a Marine rated TCW-3 two stroke oil mixed at 50:1

Again, the price of the oil is cheap insurance against the cost of a rebuild.

Clean carbs, good fuel lines, rebuild the fuel pump, mid-grade NAME BRAND fuel.

Timing set by the book.

Messing with settings as a pretty sure way to find out what a rebuild costs.

Why a specific brand fuel? All gasoline from every station comes from the same refineries. The different brands just add their own proprietary additives to it. Does techron, vpower, etc really matter with outboards?

 

[CharlieB]

Re: 83 85 HP force outboard idle and exhaust question

The BASE gasoline may come from the same refineries, however, NAME BRAND retailers uses better additive packages to meet the Octane requirements for each grade, where the OFF-Brands use the cheaper method, using alcohol up to the 10% allowable.

Alcohol DOES have a higher octane rating and is often used to 'boost' octane ratings, not really a problem in cars, but in power equipment, those running at full power, the alcohol DISPLACES gasoline, causing the mixture to slightly LEAN and raise combustion temps.

Generally outboard manufacturers jet their engines plenty rich so the alcohol should NOT normally become a problem, BUT......... add that to a restricted fuel filter, weak fuel pump, and you suddenly have a recipe for melting pistons.

Not to mention the alcohol's affinity for absorbing and holding water, causing carburetor corrosion, accelerating fuel jet restriction, making annual carb cleaning a very good idea.

NAME BRAND fuels generally have a lower alcohol level than the off-brands, is a few cents difference in price worth risking a rebuild?

 

[erikpn]

Re: 83 85 HP force outboard idle and exhaust question

The BASE gasoline may come from the same refineries, however, NAME BRAND retailers uses better additive packages to meet the Octane requirements for each grade, where the OFF-Brands use the cheaper method, using alcohol up to the 10% allowable.

Alcohol DOES have a higher octane rating and is often used to 'boost' octane ratings, not really a problem in cars, but in power equipment, those running at full power, the alcohol DISPLACES gasoline, causing the mixture to slightly LEAN and raise combustion temps.

Generally outboard manufacturers jet their engines plenty rich so the alcohol should NOT normally become a problem, BUT......... add that to a restricted fuel filter, weak fuel pump, and you suddenly have a recipe for melting pistons.

Not to mention the alcohol's affinity for absorbing and holding water, causing carburetor corrosion, accelerating fuel jet restriction, making annual carb cleaning a very good idea.

NAME BRAND fuels generally have a lower alcohol level than the off-brands, is a few cents difference in price worth risking a rebuild?

I know alcohol is bad for outboards, everyone here does. This is a different matter though, and there needs to be a reason before you can jump to the conclusion that name brand gasolines have less alcohol in them. Do you have ANY evidence or links to testing done that show name brand gasolines have lower levels of alcohol in them? By how much?

 

[CharlieB]

Re: 83 85 HP force outboard idle and exhaust question

Its been a few years but I used to send fuel samples in for testing, never saved any of the results.

I kept seeing more carb corrosion AND my chainsaw started boiling the fuel in its tank, not a pretty thing to have your saw spewing fuel on you while cutting stuff.

The name brand fuels didn't boil and squirt out the vent and the tests clearly showed them to be only 2 to 2 1/2 percent while the off-brands were running 7 to 9 percent.

I don't buy off-brand fuel and don't recommend it for ANY power equipment.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

George,

Did you ever weigh your boat? Did you ever check your engine with a hand held induction tach? The reason I ask is that 5000-5500 rpm is a standard with the two stroke engines. It has been explained to me that i has to do with the nature of the two stroke principal. If you are still getting in the low 4000's, even with a lower pitch prop, something is still not right. If I lower my prop pitch to 17, I get almost 6000 rpm.

It's possible that your boat is heavy and/or you have a tach indication problem.

John

 

[erikpn]

Re: 83 85 HP force outboard idle and exhaust question

Its been a few years but I used to send fuel samples in for testing, never saved any of the results.

I kept seeing more carb corrosion AND my chainsaw started boiling the fuel in its tank, not a pretty thing to have your saw spewing fuel on you while cutting stuff.

The name brand fuels didn't boil and squirt out the vent and the tests clearly showed them to be only 2 to 2 1/2 percent while the off-brands were running 7 to 9 percent.

I don't buy off-brand fuel and don't recommend it for ANY power equipment.

I think this is only anecdotes and guessing on your end, I doubt you did any testing at all. I decided to do some quick research online..

"Consumer Report attempted to test the differences between brand of gasoline in relation to acceleration and fuel economy, but scrapped the test because the little differences found were no more so than the differences found from other factors such as air temperature and humidity level."

"Just how much of these additives are added into the tank? The amount varies, but for some it?s a quart of additives for an 8,000 gallon tank."

http://www.stopbuyingcrap.com/stop-buying-crap/brand-conscious-buying-3-gasoline/

Also...

"MTBE (methyl tertiary butyl ether -- this is ether) and ethanol are blending components, not additives. However, you'll see them called additives in many places by many people. Blending components are part of base gasoline."

http://www.vettenet.org/octane.html

So there is no difference in the amount of ethanol between gasolines. The same truck, carrying the same blended gasoline with the same ethanol content, goes to the generic place and pumps it up, then goes to the brand name place and pumps it up from the same tank. After pumping, they add their own additives, as much or little as they want, and start the marketing project..

 

[collegefund]

Re: 83 85 HP force outboard idle and exhaust question

John from MD,

No, I havent weighed it, I guess I could at a truck stop? But then i'd have to unload and come back with just the trailer or make guesses at its weight. Also, I have only relied on the Faria tach I installed, though I sounds* like it accurate.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

If you search the NADA blue books, they give you the weight that the boat, motor and trailer are supposed to be. Junk yards have scales and don't charge much to check. If you can't find your specific combination in NADA, then check the Bayliner section for engine weights. You can estimate your trailer at 500# which is a ball park figure for 16-18 foot single axle trailers.

John

 

[collegefund]

Re: 83 85 HP force outboard idle and exhaust question

Good call. I was actually looking at that today lol. It says 1275 lbs. dry online. As soon as I get a free moment ill find out where the nearest scale is and haul it down there and get back to you.

Thanks,
-George

 

[Realgun]

Re: 83 85 HP force outboard idle and exhaust question

I also have a Bayliner 1700 with an 88 85 Hp Force. I only get 30.1 on the GPS. I had to find a 20 pole tach, which is not easy. I boat at 4700Ft altitude also.
So my reading with 3 people in the boat are 4500 rpm and 30.1 mph on the GPS unit.

I run a 15 pitch Huslter prop on this boat. Don't ask me how as it's the older version not the new Hustlers.

So basically I am a bit slower than I should be, me thinks. I will do a decarb and see if that helps.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

Realgun,

If your carbs have not been rejetted for the altitude you are at, you could be running leaner than it should be, this will affect your speed.

Decarbing most always gives you better performance. If you have never done it, I suggest doing it twice leaving the solution in the engine overnight if possible the second time. Then, the first time you run it, open it up to WOT and that will blow the carbon out.

John