1990 100hp 2+2 Link and Sync questions

[nwboater45]

I am new this motor and still trying to dial it in. One issue was fuel and will need to drain the tank. Anyways the questions I have while doing a link and sync are:

1. What is the best way to ground the plug wires? Anyone have any good diagrams or photos? A really good description will also help.

2. I am assuming that the timing light is still connected to the #1 plug wire....correct? The service manual calls for the light to be connected to the block.

3. When it is all said and done what is the typical idle RMP's in neutral while the motor is in the water tank? I know it is suppose to be 650 while in gear but I can't run it in the barrel in gear for very long. I want to get it to a good point then adjust it on the lake.

Thanks.

 

[nwboater45]

Bump....

Tonight I rigged my own grounding setup and got the timing as close as I could. I got it to idle pretty good with the motor in a barrel. It is not the smoothest I have ever heard but I guess these motors don't idle well.

Anyways......what RPM's should these be running at while in the driveway on muffs or in a barrel? I have it idling around 1,000 and it shifts fine into gear but I can't keep it in gear long enough to set the idle down before I blow too much water out of the barrel.

Any help?

 

[flyingscott]

Those motors should idle very well. Why are you playing with the timing that seldom to never needs to be adjusted. The correct rebuild kits are available from mercury. For that motor you HAVE to have a factory manual.

 

[nwboater45]

Scott if you where to read the posts on here about this engine like I have most would agree that these engines aren't the best at low idle. Also if you where to read the factory manual like the one I do HAVE for the motor along with the Solec as part of the link and sync procedure section it has you set the idle and max timing. Like a lot of motors over time the timing can become off for a simple reason like a back fire. Maybe it is idling great. I am an inboard guy and this is my first outboard. Maybe because it is an inherent nature of a 2-stroke that I think it is off by just a bit. All I was asking for now is what people have for idle RPM's in the driveway vs what they have on the water.

 

[flyingscott]

I owned one very familiar with that engine the idle goes to crap because people feel the need to play with it. YOU are absolutely WRONG about the timing moving on a 2 str outboard over time. You may want to buy a factory manual since you seem to have no idea about how timing works on an outboard motor. Since you know more than I do good luck with your motor.

 

[racerone]

A sheared flywheel key is the only thing that would change the timing,----And you can not determine / find a sheared key using a timing light.

 

[CharlieB]

Max timing is adjusted with the motor NOT running, only cranking on the starter.

Timing changes by movement of the ignition trigger ring being rotated by the throttle arm.

Timing over time DOES NOT CHANGE more than a degree or two, and that is only if the linkage connections wear a LOT.


Idle speed is controlled by base timing, the idle adjust screw advances/retards timing as it idle there should be a gap at the throttle pick-up roller, all carbs should be fully closed.

My 115 2+2 idles perfectly. Once all adjustments are perfected EXACTLY as spelled out in the FACTORY service manual the transition from two to four cylinders during throttle opening is seamless. You will NOT be able to tell at what point the bottom two cylinders begin to fire and make power.

 

[Texasmark]

Not getting into the conversation per se but I have a few questions/comments.

My 90 triple had plastic adapters that adapted the linkage wiring to the control and controlled arms. Several of them were broken when I bought my last used 2 year old engine (2002). That could impact the setting.

If the idle timing were off, the idle set screw on the throttle linkage arm could be used to bring it back in tolerance for the specified 675 +/- 50 idle rpm with the engine on the boat, in the water, in F gear moving along.

Since that engine idles on 2 cylinders at idle, it's not like a V8's smoothness. Used to be, back when OMC had the Big Twins (alternate firing to help firing smoothness) they used very soft rubber bushings between the engine and the clamp bracket to soften the impact on the boat/occupants, even though you could see the engine rocking back and forth.

Nowadays, with Power Trim and Tilt, the rubber vibration dampers are a lot harder to assist in controlling the engine when running at high speeds and at high trim angles. So yes, if maladjusted, you could have what seems to be significant vibration. My triple wasn't all that smooth at idle and it had one more cylinder to fire every rev. Only thing going for the 2 stroker as compared to the V8 in that capacity is the 2 stroker hits every rev where the V8 has a power stroke every other stroke making the 2-2 like a 4-4 or a 3-2 like a 6-4.