83 85 HP force outboard idle and exhaust question

[Ady Wright]

Hi All,

first of all i want to say thank you to this site, i recently purchased on older 83 16' bayliner cuddy, with the Force 85 HP outboard, never worked on one before, i bought the seloc manual which i found very confusing until i read posts on here.

I have changed the trigger ring, both ecms/coils/ re timed it, all with help from here and i have just run it for a week here in Kentucky!

i can get around 43 MPH (via speedo on dash), is this good?

i am having smoking problems but i think this is normal, i have dropped from 16oz of 2 stroke per 6 gallons to around 5 and it still smokes.

If i run the engine at 3/4 throttle (around 33 MPH) then go to idle speed i get steam around the ouboard, is this normal? it stays steaming until i am out of the no wake zone.

i have tried alsorts of timing set ups, the 28 btdc is no good, i cannot get full rpm, at 34 btdc i get a good solid high rpm but my idle seems to be affected.

i seem to get around 30 miles to a 5 gallon tank, is this normal?

Again, thanks for this site, because of this i adore that Force outboard (i came very close to pouring fuel over it and burning it).

 

[pnwboat]

Re: 83 85 HP force outboard idle and exhaust question

You should be very careful when reducing the amount of oil. You risk doing serious damage to your engine. Dropping from 16 oz of oil per 6 gallons to 5 oz of oil per 6 gallons is going from 50:1 (recomended) to about 150:1. If you operated it for any length of time at 150:1 ratio, you're lucky you didn't seize the motor up. You may want to check the compression to see if any damage has been done to the rings/pistons.

Advancing the timing to 34 degrees is also detrimental to the motor unless you have high octane fuel. This is a recipe for a burnt piston. You shouldn't set the timing more than 30 degrees static timing to be safe.

43 MPH for that set up is pretty good.

Most of the older 2 strokes have a tendency to smoke. Very basic design and not as clean as the newer 2 strokes. Also not as fuel efficient.

 

[CharlieB]

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.

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

Again, top class replies, thank you.

I am out on it Again Friday night, i will reset to 30BTDC, also i have been using "normal" 2 stroke oil, so i will ditch the fuel and refill with the recomended oil at the specified ratio.

the impellor was checked and looked to be new for water cooling.

I read on another thread about exhaust fumes in the "tower" from the Powerhead to the Lower unit being a possible exhaust connection issue. I think i will check this also as i have noticed blue smoke whisping around in there at low idle.

Thanks Again.

 

[collegefund]

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

 

[sho3boater]

Re: 83 85 HP force outboard idle and exhaust question

Better oil may smoke less. The issue far as I can see is the leg has a rubber boot that goes to the two holes on the back that spray water. Unfortunately they also spray exhaust at idle. There is only a rubber boot in there that just sits there, if it is off the exhaust goes up into the motor cover. I set my idle jets lean as I can get away with and that helped but it still does it. Now I am investigating taking that leg apart and plugging that big internal hole one way or another, then install a water pressure gauge instead. My pump/impellor looks like new. Most all other motors spray mostly or all water and not exhaust.

I have a 16' bayliner capri BR/force 85 ('83) and ran under 40 speedo with a 19p SS prop. I did a few things and sharpened the prop some and the rpm was higher than recommended (5800?) with a clamp on tach and it ran 43 gps. I worked on a few things and had the prop thinned and slight cup added. Now it shows 43mph, got a tach in the dash and it shows under 5400 IIRC but it has not been checked with the digital. It runs lower rpm than it did and same speed. I have regular gear oil in it and it will usually gps 42 now, one person, not much gear in boat. It does have a newer block in the motor. Only odd thing is that when the rpm gets higher (before the prop cup) it would make a whistling noise, I never could figure it out. Sounded like it was from the carbs. Otherwise runs great, will pop on plane fast considering it is running a taller prop, in fact it planes faster with trim than not. It does take some gas 6 gal does not last long, but I'm not one to go slow either. However at half throttle it sucks it down nearly as much IMO, and that is typical for older motors. Since I have little into this boat and can't use it much now it is a great deal.

I have a new pickup but old speedo, it reads 48 or something not positive. It is hard to see and I use the gps and tach mostly. I should pick one up to match the new tach. I have a video of it at WOT but that was before I had the tach in it. Also I raised the motor at least 1/2" on the transom with a spacer when I remounted it. At full trim it will cavitate some when I turn and grab again when I straighten. Sounds cool though, lol, and it does not gain that much rpm. Top speed is very near full trim, sometimes it will porpoise a little and I drop it a hair it stops.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

Ady,

There is a rubber coupling that goes to the low speed relief ports inside the cowl. If it cracks or becomes loose, it allows exhaust gas to enter the engine intake and the performance drops off noticably. If you are getting 43MPH, that is about the best you will get out of your motor/boat combinations.

Shoe3boater,

If you block the idle relief port in the leg, you will probably not get your engine started. In the rare instance that it starts, it will not idle properly and will load up and shut off.

John

 

[sho3boater]

Re: 83 85 HP force outboard idle and exhaust question

Ady,

There is a rubber coupling that goes to the low speed relief ports inside the cowl. If it cracks or becomes loose, it allows exhaust gas to enter the engine intake and the performance drops off noticably. If you are getting 43MPH, that is about the best you will get out of your motor/boat combinations.

Shoe3boater,

If you block the idle relief port in the leg, you will probably not get your engine started. In the rare instance that it starts, it will not idle properly and will load up and shut off.

John

I plugged it once and it seemed ok, but then it just leaks into the cover and I don't like that at all. How do other motors keep the smoke out of the relief? This is the best starting motor I've ever had. All winter and it starts within say 5 seconds of cranking, and instantly when warm. The auto place here only had champion plugs of all things and they seem to work great. I always run NGK in most other motors, never bothered to get them for this.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

It all depends on the size of the engine. Larger engines need relief ports because of the water pressure at the main exhaust which is behind or through the prop. Smaller engines have less pressure because their exhaust is usually not that low. I have had some that only had one underwater exhaust. The Force engines seem to have been designed to have a idle relief port and we have to live with it.

John

 

[sho3boater]

Re: 83 85 HP force outboard idle and exhaust question

What it probably needs is a water tube and/or cup there. That would keep the steam out of it, the steam seems to spread the stink badly it is not near as bad when cold. I thought it ran hot but it feels right like other motors, and I was told that is normal temp for a thermostat motor. Maybe I can mix some pine oil in to make it smell better It sprays water out pretty good, but the steam just stinks and swirls all around with a little back wind.

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

ok i am completely stuck now, in the last 2 weeks i have done and had the following effects;

i changed back to the correct ratio of good grade 2 stroke oil. 16 oz per 6 gallons.

i took the boat out, i struggled to get the engine started. after starting then adjusting the idle mix screw and tower screw i couldn't get to throttle any more than half throttle without the engine dying.

i then checked the BTDC at WOT engine running, i managed to reset the timing to co-inside with the timing mark (only one TDC and BTDC shown on the flywheel).

the engine performed amazingly for the next 5 hours. i managed to get a low idle basically at trolling speed, the top end gave me around 37 mph.

the boat sat for 5 days, then took it out at night for a night fishing trip.

the engine seemed to have reverted back to how it was before. very hard to start, after 2-3mins of idle speed the engine spluttered and died, any throttle at all and the same thing, primer bulb not affected, and was hard.

the next day i sprayed the carbs with seafoam, put sea foam into the tank, 5 gallons i used around 8 oz of sea foam in the tank.

i removed the flywheel, i noticed the the stator (brand new) looked to have picked up a rusty coloured substance. at this stage i recalled having some trouble the previous time i removed it re-installing it. (maybe this is why the engine seemed to go out of time). I made sure the key way and key were properly aligned and the flywheel dropped straight on. no play in the tower, trigger or mechanism.

submerged the lower unit in water tank, the engine started first time and idled a little rough with copious amounts of white smoke, the engine idled well for a good 15mins.

the prop was removed and i gave it a little high idle and the engine cut out.

after messing with the idle screws and port settings for the next 4 hours i decided i was wasting my time and had to get the outboard in the water to do a proper check.

yesterday i couldn't start in idle at all but managed to get into gear (bypassed the neutral switch) and the engine started straight the way and moved, but only for 30 secs or so, the engine died, but fired straight back up, ran 30 secs then died.

again, done a dynamic test by removed 2 and 3 spark caps, full throttle, crank, and set the BTDC to the mark on the flywheel.

managed then to get it to start in idle, i even managed to set the carbs idle screws and got the idle to around 800 rpm's. i then put the motor into gear and it stalled instantly. i tried to up the idle speed to 1000 rpm, set the motor in gear and ran idle prop turning at 800 rpm.

then again, as soon as i throttled up, the thing would die!

this time it was a nightmare trying to start it. the most successful way was to pull out the throttle arm and push forward for hight idle (measured at the flywheel 2500rpm) good for 10 secs then rough, if i pulled back on the throttle to get low idle it would die.

in the end it was impossible to start, the battery lost its charge and i had to get towed in.

some other things i noticed. again, exhaust smoke in the stack, the rubber boot that goes to the 2 power stroke holes is in place. (i am going to strip the lower end this week to see if its coming from that area.)

i am getting fuel collecting in the airtake.

the time i did get it to move in low idle i heard the "normal" engine pitch, then after 30 secs of moving we all heard the engine sound drop a pitch and it was like it was coming from deep within the motor. it died after 5 mins.

i also heard a "pinking" sound like a ticking high pitched sound, whisch once hearing i immediately turned it off.

i have a compression tester and am going to try and diagnose tionight if i have bad rings, i am confident the pistons are ok, i can see carbon build up but no signs of melting.

i have changed the fuel pump diaphram, but ready through some posts today i am going to check the relief valves in the pump.

also in this thread i noticed a post about a rubber tube in no.1 carb? a releif valve? i can't see this at all, the only tube i have are the fuel feed tube and the tube that goes into the air intake cover.

is the sea foam in the tank causing me any grief?

any other ideas?

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

If your fuel recirculation line to the intake manifold is blocked, you will have hard starting and the engine will make more smoke as you are flooding the number three cylinder.

The vacuum line under the intake manifold runs to a fitting under the number three carb. Inside that fitting is a small orifice. It gets clogged easily. You need to unscrew it and blow it out with air or carb cleaner. This will keep fuel from puddling in the intake and flooding the lower cylinder.

John

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

john,

you are a star!

is this the hose that goes into the cover that goes over all 3 carb intakes? then it goeas back to the block?

If so i can easily check that tonight.........

So my jobs for tonight are to check that fitting.

Pressure check the cylinders, and if i have read right then i need to see around 135 psi? with all 3 cylinders within 15psi?

Check the check valves inside the fuel pump.

question, how in the world do we get around the ethanol problems with these older systems? is there any product that will kill off the yeast and stop it growing?

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

Yes that is the hose. The fitting screws out of the crankcase and probably will be clogged. It is a very small hole that is why you need air or pressurized carb cleaner to clear it.

Compression should be between 130-160 10-15# spread between them. If they are off, a couple of good decarbs will usually loosen the rings and bring the compression back up.

To check the check valves, you want to dry them as best as you can then, using a pen or toothpick type device, gently push in on the two valves were you can see the poppet. If they stick, they need replacing. In my experience, the amber colored poppets were the ones that stuck. The black or dark greay colored did not.

There are several fuel treatments out there and some people swear by them. I don't need them as I have removable tanks.

I suggest you google some terms such as gasahol, 10% ethel, Phase separation. You will get some good info.

John

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

John! your the man!

i checked the comp first last night! i cannot get the engine running so i am doing this in ambient temperature, the dry readings were low at around 75 psi! all within 15psi.

i then fogged the bores as best i could, the reading then went up to 90psi, all with 2 psi of each other. i had the neutral switch by passed and the throttle wot.

i then inspected the check valves! exactly as you stated, the center one was solid! the other 2 look ok! must be why i died throttling up.

then i checked the hoses you mentioned! crammed full of the sound insulation from the cowling. cleaned out, i also stripped the rest and they were fine.

i have now stripped out all the foam from the cowling!

you have now given me an excuse to lake test it wednesday night after getting the new parts for today.

Many thanks to all you guys on this site.

Ady.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

Your compression is still way down there. You need to do a couple of good decarbs to try and free the sticking rings.

John

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

Thanks John,

sorry to sound "thick" here, but what is the best way oonce i get her running? sea foam straight into the air intake of each carb?

 

[pnwboat]

Re: 83 85 HP force outboard idle and exhaust question

Hopefully it's just sticky rings. The first post on this thread you mentioned you were running it with 5 OZ of oil per 6 gallons of gas to try and get it to stop smoking.

 

[john from md]

Re: 83 85 HP force outboard idle and exhaust question

No, you want to follow the steps for decarbing in the FAQ. The FAQ is found at the beginning of the iboats maintenance forums.

As pnwboat stated, hopefully it is just sticky rings. I believe that it may well be because your fogging oil brought your compression up some. If you had any damage, I feel that the compression spread would be wider between cylinders.

John

 

[Ady Wright]

Re: 83 85 HP force outboard idle and exhaust question

John,

Again, 100% accurate on your diagnosis. Thank you.

de-coked as in FAQ, i can now set idle, with 3 men in total weighing around 700 lbs, the boat went to 40 mph! again, thank you.

hopefully my last question.

i have always had problems with black spark plugs. i haven't checked with the new set up yet, i also need to do a new comp test now i can get the engine warmed up.

what if it all checks out and i still have black plugs after a run? do i advance or retard a bit on the timing?

sorry to be a pain, but you have me so close now to a brilliant running motor.