Timing and idle adjustment on 1987 85hp Force

[HydroGeek]

In the process of debugging and tuning my 85hp force. 1987(B) motor. Electronic ignition. I've watched the carb and timing videos, but my motor is a little different, and I'm not the most mechanically inclined.

Initially, I lost spark to #3, and it turned out to be a bad stator. Replaced the stator, spark on all three. Motor is reluctant to start cold. I have to put it in fast idle, and give it a shot of starter fluid (I know. Bad stuff). Once even slightly warm, the motor starts right up. Acceleration is not smooth from idle to WOT. But once above 3500RPM, motor runs well. With the prop I have, at my altitude (5500 ft) my engine max's out at 4800 RPM and runs smoothly and well.

Electric choke works well. Carbs seem to be synchronized well.

I need to fix the low end response, and I think I have screwed up the timing during my "fixing".

On this motor, is the timing tree adjustment low on the engine, near the back of the throttle linkage, or is there a timing adjustment under the flywheel like the 125hp motors? (I don't have the motor close by to check)

I set up the cam adjustment with the ball linkage off (Frank's video), re-attached the linkage, started the motor and adjusted the idle speed using the screw and set nut behind the cam linkage. Now I am thinking that I may have been screwing up the timing.

Questions :

1) It appears that timing is initially set at WOT, for 28 deg, while cranking. Once this mark is set, then I start the motor, at idle, and check / set for idle timing. Is this correct?
2) What is the means to set the idle speed? Do I lengthen the ball joint coupler?
3) If the ball joint coupler is not used to set idle speed, how do I correctly set the length of the coupler?
4) Is 4800 RPM the correct max revolution speed? Or do I need to resize my prop?

Thanks for the help!

 

[SkiDad]

1 - Setting timing at 28 is correct. You don't have to worry about timing at idle if you set it at WOT while Cranking. Don't forget to ground all 4 plug wires.

2 - the idle is the big flat head screw and nut at the bottom of the tower (it will not mess up timing) - set it to about 1100 rpm in the driveway after warm. Then recheck in the water for about 750 rpm in gear on the water. Make sure you tighten the nut after each adjustment (don't ask me how I know) But before you set the idle check your fuel mixture as this will call for a idle speed change after you mess with it. Idle speed is key to getting these engines to start well.

The timing adjustment is just like the 125s - right under the flywheel there are black vinyl blocks that open or close the gap - if your timing is correct just leave it alone (also don't ask me how i know - ha ha )

3 - Frank covers this in his video.

4 - 4800 is fine and won't hurt anything. If you need more gitty up for skier drop down 2" of pitch.

try running some mercury quickleen in your tank - that will help clear out the junk.

clean or replace your spark plugs. NKG BUHX

 

[HydroGeek]

Oh great. so now I have a new question : -) How do i check the fuel mixture?

Sounds like I was adjusting the correct screw for idle speed. But that still leaves an open question on the ball linkage thing. how is that correctly adjusted?

I also had my idle set at 800 RPM in neutral. Seems like I need to bump that a bit. However, I also remember that I am nearing the far range of that idle screw. This make me think that maybe the ball linkage coupling may not be set correctly?

Thanks for the input!

 

[Frank Acampora]

The ball link for carb cam is adjusted at wide open throttle. As I show in the video, you initially unclip it and adjust the carbs closed by setting the scribed line on the cam to tangent on the carb roller. THIS establishes a base point. Then, with the controls at wide open throttle (engine not running) you adjust the ball link so that the carbs are essentially open to horizontal. Note that when all adjustments are made to timing and idle speed, the scribed line on the cam will no longer be tangent to the roller at idle. All this is covered in the video. please re-watch until you understand it.

Understand that ALL systems are interconnected. A change in timing or fuel mixture will require a change in the idle stop screw. However, once set, the cam and ball link are not affected and should not change. Understand also that a change in prop pitch will usually require a change in the idle stop screw setting. That is why idle speed is set in the water in forward gear.

At your altitude, unless the carb jets have already been changed, the engine will be running a little rich. Since at high speed the engine can accommodate a little extra fuel better than at low speed, it will run better at high speed. Too rich at low speed will slow the engine, making it necessary to increase the idle speed by setting the stop screw further in.

I don't usually recommend that people with little experience set the low speed needles because there is a distinct possibility of setting them too lean and doing massive engine damage. Never set the low speed needles to less than 3/4 turn out from lightly seated no matter what the quality of the idle is.

You must test the low speed setting ON THE WATER by doing "hole shots" I believe I have covered this in a written "synching carbs and timing" sticky.

 

[HydroGeek]

OK.. thanks Frank. I'll go over the videos and stickies again.