Link and sync procedure?

[DunbarLtd]

88 Force 85hp

Im having intermittent sneezing issues on startups after turning mixture screws out to 1 1/4. At times it will fire within a single crank and run fine.

Not sure if this is relevant but the motor shakes a bit much when idling @ around 1500 rpms or about 5-6mph. Shakes the windows and rattles everything. Dont notice it at idle speed. Seems to run fine at mid and high throttle.

I wanted to do another link and sync but I dont see anything about where to set the idle speed screw before I begin.

Last time I did a link and sync i had to screw in the idle speed screw so far (750rpms in gear) i almost ran out of threads.

If the idle speed screw isnt set right before linking and syncing isnt it throwing off the position of the trigger and affecting the timing compared to the final throttle position? Or am I not understanding something here?

Hopefully that makes sense. Thanks for any clarification on this one.

 

[jerryjerry05]

You should set the air screws before the link and sync.
Then redo after the procedure.

The sneeze isn't normal.
You might be sucking air someplace?
Carbs on tight? ,gaskets good?,
Do the starting fluid test?, spray around the intake side, include the 3 port covers and see if that makes a difference?
One little sneeze, cough can blow the gaskets.
Test the trigger wires, one might be broken and making just enough contact to run(happened to me).
Check for loose bolts?

 

[Redbarron%%]

I have a question.
When I try to adjust the idle mixture on my 90 hp Sport Jet I start at 1 1/2 turn out from the lightly seated position, but I have tried to adjust for "popping" and don't really find that point, but I do get a king of rattle that sounds like it is in the top of the engine.
Instead of popping the engine just will run rough and stall.
Is the rattling I hear the popping?
I worried that the rattling I was hearing was a bearing problem and tore the engine down and rebuilt it only to find that the rebuilt engine does the same thing.
Perhaps with the different formulation of the fuel a little richer mixture would be needed?
I usually run Marine non-ethanol gas with Mercury synthetic oil.
I am also working on making sure the timing curve is correct after changing over to the late model CDM ignition.
I have fabricated a bias circuit that goes inline as near to what I can find for the circuit, but I have not had a change to test under load on the water yet.

 

[The Force power]

88 Force 85hp

Im having intermittent sneezing issues on startups after turning mixture screws out to 1 1/4. At times it will fire within a single crank and run fine.

Not sure if this is relevant but the motor shakes a bit much when idling @ around 1500 rpms or about 5-6mph. Shakes the windows and rattles everything. Dont notice it at idle speed. Seems to run fine at mid and high throttle.

I wanted to do another link and sync but I dont see anything about where to set the idle speed screw before I begin.

Last time I did a link and sync i had to screw in the idle speed screw so far (750rpms in gear) i almost ran out of threads.

If the idle speed screw isnt set right before linking and syncing isnt it throwing off the position of the trigger and affecting the timing compared to the final throttle position? Or am I not understanding something here?

Hopefully that makes sense. Thanks for any clarification on this one.

Here's the instruction(in case you don't have this already) follow them to carefully!!
I found out that if not followed or misunderstood correctly, you're not getting it to run right.
I hope this is of any help

 

[DunbarLtd]

Thanks May. I have that manual. As I stated it doesnt mention where to set the idle speed screw before beginning. I assume somewhere in the middle to give myself room for future adjustment?

Also when final setting of the idle speed should the throttle plates be completely closed while the motor is in neutral? I think they are slightly cracked right now. Ill have to go check again to make sure.

The last thing is the air mix screws adjustment. Says to start 3/4 out and go in 1/8 til it chuggs then back out 1/8 yet i see every single comment on this site in regards to this topic stating to start 1 1/2 turns out. So thats confusing as well. But thanks for those documents. They may help others.

Ill try the starting fluid test around the intake/gaskets and look for air leaks and go by the book on doing the link and sync and see what happens.

 

[The Force power]

Thanks May. I have that manual. As I stated it doesnt mention where to set the idle speed screw before beginning. I assume somewhere in the middle to give myself room for future adjustment?

Also when final setting of the idle speed should the throttle plates be completely closed while the motor is in neutral? I think they are slightly cracked right now. Ill have to go check again to make sure.

The last thing is the air mix screws adjustment. Says to start 3/4 out and go in 1/8 til it chuggs then back out 1/8 yet i see every single comment on this site in regards to this topic stating to start 1 1/2 turns out. So thats confusing as well. But thanks for those documents. They may help others.

Ill try the starting fluid test around the intake/gaskets and look for air leaks and go by the book on doing the link and sync and see what happens.

I have read that about the comment also and I'm a firm believer!! that's why I CROSSED IT OUT don't go with that!

Start off with the Idle-screw in the middle.... if you run out of thread to adjust; something else is not working right you are try to over compensate
when you say; the throttle-plates are slightly cracked open, is the tower-arm in the high-idle position?

 

[jerryjerry05]

You said: As I stated it doesn't mention where to set the idle speed screw before beginning."
The idle screw (bottom of the towershaft) is set where it allows the engine to idle about 800 rpm's in the water
and in gear.
Inital settings on the hose, about 11-1200

The screws on the top of the carb are air/fuel mix screws.​

The air screw setting according to the factory for the 85hp is
one turn out and leave it there.
Look on U-tube for the video from FrankA about doing the L@S.
http://youtu.be/tDoR64jP5l8 this is the video.

About the one turn out.
Some 85's just won't run right at 1 turn out.
I've seen them set as far as 3 turns out to idle.
If your motor runs good at 1 then set it there.
Both of the 88/85's I had ran good there.

 

[The Force power]

With the "experience" I have gathered working on these now is;

A final fine tuning or adjustment on the throttle cam was necessary to have it idle/accelerate smoothly (in gear/ in water)

 

[DunbarLtd]

With the "experience" I have gathered working on these now is;

A final fine tuning or adjustment on the throttle cam was necessary to have it idle/accelerate smoothly (in gear/ in water)

So essentially you are advancing/retarding the timing or are you just cracking the throttle plates more? And this adjustment of the cam arm will not affect wot and the carb plates opening fully?

Ive got the slack out of the carbs linkage and adjusted the cam arm so the plates are horizontal. Now after i reconnect the ball link and i return it back to the stop on the block, i noticed the trigger isnt all the way back. Which is likely because the idle speed screw is threaded on about half its full travel. So its advanced/retarded ?? How many degrees???

Why not set the initial setting of the cam arm to wot, then spin the idle speed screw all the way out, so the trigger is as far back at it can go. Im assuming this would be 0 degrees? And then get on the water and adjust for idle speed by turning the screw in. Why start with the screw so far out if you dont know what degrees it is set to?

 

[DunbarLtd]

Ok I did some reading and found this comment which cleared up my confusion.

"To mechanically zero, it means the carbs throttles are are closed or vertical position; the #1 piston is at TDC, the flywheel zero marking is aligned with the vertical timing indicator, the cam slot marking should be aligned with the eccentric screw slot marking, the control throttle in neutral and the idle screw is not pushing against the block but just barely touching. If you time it in this position, the flywheel should be indicating zero degree with reference to the vertical timing mark.

After attaining the above adjust timing (statically) and set to 28 degrees at wot. After setting this you should set the idle screw for idle rpm of 750 RPM idle in gear in water. This usually translates to 900~1050 rpm in neutral on muffs or tub.

The timing tower is zero'ed out when #1 piston is TDC with the flywheel zero marking aligned with the vertical timing indicator, carb throttles closed, idle screw not pushing against the engine block and finally the cam marking aligned with the eccentric screw slot. If you push the control lever all the way forward, the timing tower should also move at its maximum travel and opening both carb throttles in full horizontal. If they do not fully open adjust the link rod swivels and/or the eccentric screw or the tie bars on the carbs, as appropriate."




As it sits now after doing the link and sync the idle is about 4.5-5 degrees with the gearbox in neutral. And WOT is leaving the carb throttle plates horizontal so i think i got it right.

The idle speed screw is out a little less than half way. I will need to fine tune on the water of course but I see why you need to thread the idle speed screw out some otherwise it probably wont start as the plates need to be cracked just a tad and the timing slightly advanced.

 

[The Force power]

Yes, I was tired last night so I did not respond AND I could not of explained it so well as you just did.
all I could say is; read/understand/follow the instructions to a T

 

[racerone]

Throttle plates on most outboard motors are CLOSED at idle.-----But they are not really closed because they have holes / cutouts to allow a calibrated amount of air ( with fuel /oil ) to go into these 2 strokes.----Idle speed is controlled by backing off the TIMING.------Remember that this is wasting fuel by retarding the timing.----But the motor at idle needs the OIL to get in there.

 

[The Force power]

the cam slot marking should be aligned with the eccentric screw slot marking.

I just found something in your write up that; IF..... I understand you correctly is not correct.

The marking in the Cam should line up with center of the eccentric Screw (not slot marking) by turning the eccentric screw you adjust the bushing in a way that it barely touches the cam (this is done while the adjustable connecting rod attached to tower-arm is disconnected from the cam)

 

[DunbarLtd]

Throttle plates on most outboard motors are CLOSED at idle.-----But they are not really closed because they have holes / cutouts to allow a calibrated amount of air ( with fuel /oil ) to go into these 2 strokes.----Idle speed is controlled by backing off the TIMING.------Remember that this is wasting fuel by retarding the timing.----But the motor at idle needs the OIL to get in there.

When you screw the idle speed screw IN are you not actually ADVANCING the timing? The trigger is moving forward once you start screwing the screw in or am i looking at it backwards and the trigger moving is actually retarding the timing when it moves?

When I set it all up at first I followed those directions. Found #1 TDC first, verifying 0 degree on flywheel and block pointer.

And then backing OUT the idle speed screw all the way until the threads were just barely touching the block. This set the trigger all the way back to what i believe was 0 degrees??

Removed all slack from carb linkages. Then I adjusted the throttle link arm so the carb plates were horizontal @ WOT while trigger (tower shaft) was fully advanced.

So once all that was adjusted I THEN turned IN the idle screw almost halfway until i thought it was close to where itll be when running in gear @ 750rpm and then the line on the cam was pushed past the roller. Which in doing so cracks the throttle plates just a bit. Confirming this with a flashlight. Ill most likely have to adjust again on the water.

I remember last time messing with it - if the idle speed was too low it would stall when put into gear, but I believe it could still start and run i suppose with them (throttle plates) completely closed - because of the holes in the plates like you mentioned.

So once it is all set up the plates will always be cracked a tiny bit when starting. How much depends on how far you turned the idle speed screw in.

Which makes me wonder how it doesnt backfire when starting if the timing isnt considered at idle? I dont know much about outboards but arent most engines timed @ idle? Why not on these???

 

[DunbarLtd]

I just found something in your write up that; IF..... I understand you correctly is not correct.

The marking in the Cam should line up with center of the eccentric Screw (not slot marking) by turning the eccentric screw you adjust the bushing in a way that it barely touches the cam (this is done while the adjustable connecting rod attached to tower-arm is disconnected from the cam)

That is correct.

 

[racerone]

Simple / blunt statements here.-----Maximum timing advance is the only thing you SET.--------Idle timing looks after itself !!-------Idle pick-up timing is the point where throttle plates start to open.------Where the timing is when engine idles smoothly just does not matter.

 

[Nordin]

As racerone stats you set the timing at WOT, the timing at good smooth idle does not matter, it will be what it will be.

Set the throttle pick up point (when the roller touches the cam) at the mark at cam with the throttle rod disconnected.
Back off the idle screw so it does not stop the timing tower at the block before the tower it self does.
Set the air/ fuel mixture screw at 1 1/8- 1 1/4 out from seated, start the engine and let it warm up.
Then adjust the idle by the idle screw so it runs at about 7-750 rpm in water or 1100-1200 rpm at muffs.
Then adjust the air/fuel mixture screw by turning in 1/8 turn and then let it pick up the adjustment for 10 sec.
Do this procedure until it starts to act up from a lean setting mixture, note the setting.
Do the same adjustment but by turn the screw out 1/8 turn and wait 10 sec etc until it starts to act up by a to rich setting.
Finally set the air/fuel mixture screw at a midpoint of this adjustments.

Then you maybe have to adjust the idle screw so it runs at 7-750 rpm in water.
Run the engine in water on a boat and check that it would not stop when you just set the engine in gear with no more throttle then just above idle.
If it stops the mixture is to lean, adjust the air/fuel screw about 1/8 turn out and check again.

 

[The Force power]

Which makes me wonder how it doesn't backfire when starting if the timing isn't considered at idle

The ignition at 30 deg. @ WOT is at; where the piston is past the intake ports, so a backfire in the sense i'm thinking of is not possible.

 

[The Force power]

Which makes me wonder how it doesn't backfire when starting if the timing isn't considered at idle

The ignition at 30 deg. @ WOT is at; where the piston is past the intake ports, so a backfire in the sense i'm thinking of is not possible.

 

[jerryjerry05]

2 ways to set the air screw.
#1 is leave it at the factory suggested setting of 1 turn out.
#2 get motor running, warm and in the water and in gear.
Set the screws at 1 1/2 turns out.
Turn the air screw in 1/8th turn, wait 10 seconds for the fuel to burn at the new setting.
Repeat this until the motor bucks,coughs, stalls.
Then out 1/2 turn.
Repeat on all 2/3 carbs.
Run the motor and see how it works.

Then check the plugs for correct burn.
Start and run wide open for 4-5 min.
The turn the key off, don't throttle back or slow down, just kill the motor.
Pull the plugs and check the color.