How to adjust idle on V-4? Bill Gohr?

[Ron V]

My motor is a 1995 Evinrude 90 hp crossflow. I pulled the service manual out from my old 1985 Johnson and apparently the linkage has changed a bit.

I have been told that you DON'T set it by turning the wheel on the cable.

I have also been told that you have to adjust the spark advance linkage. This does not make any sense to me. Why should you have to change the timing in order to bump up the idle speed? Seems to me that you should be able to have the motor idle fast enough to stay running when you shfit it without setting the timing at 30 degrees and frying a piston. What about the idle stop screw? Can you just use that and turn it in/out without binding something else?

My motor only idles around 600 rpm in gear and about 800-900 in neutral now (if you can believe the Faria tach), and consequently is a bit cantankerous when you go to restart it and put it in gear. I know that is not uncommon with 2 stroke carbed outboards in general, but I think I could make it a little more friendly if I could bump up the idle by 100-150 rpm.

[Raceman]

The best way to adjust the idle on the V4 is to back the screw off several turns. This will cause the engine to cut off. While it's off, remove it entirely, then replace it with something black, preferably a V6.

Seriously, Mercs get their idle speed by increasing initial timing rather than cracking the carb butterfles. If you'll notice, there's considerable timing advance before the carbs begin to open. In the case of all the Mercs, by changing the initial spark advance, the total advance is not affected. Far as I know OMC's are the same.

[Edited by Raceman on 08-31-2001 at 04:07 PM]

[Ron V]

That is what I was thinking too. I remember that the old inline Mercs had an idle stop on the distributor, and on the newer inlines that had no distributor you just turned the brass barrel on the cable and set the stop screw on the linkage I guess. That's why I thought that I should adjust the cable and then set the stop screw accordingly. Messing with the spark linkage would be like messing with the timing advance on the old Merc distributors, correct?

[Raceman]

That'd be my guess. I've never owned an inline without a distributor, but I'd still think they have a screw somewhere that advances the timing. I've never seen an engine of any brand that required cable adjustment for idle speed control. There are too many other things adjusted with the cable drum for that to be the only idle adjustment.

[Bill Gohr]

So his opinion is shaded so to speak. First of all you said you have the Service Manual. If so and it's an OMC one, the first thing you need to do is sit down and read the section on synchronization of the linkages. If you did and think it says to advance the wot timing to raise the idle speed, Sit down and read it again cause it doesn't. Now that i got that out of the way, what is really wrong with your engine. It's supposed to idle at 650 to 750 in gear and 900 to 1000 out. You said it does that. If you called me when I was at OMC I would tell you to put the hood back on it. You need to read the linkage section in the manual and see where it shows you to set the idle timing and the WOT timing. That engine has what we call a desmodromic linkage on it. If it's set up correctly, suprisingly enough that motor will idle at the correct speed automatically. Also, the engine is designed to run with the throttle plates closed. If you have to crack the plates to get the idle up there is something else wrong with your engine. Check the compression, clean the carbs, BEFORE messing with the linkage. Very seldom did we have to fudge adjustments with that linkage and especially on a 90hp. If you have any questions on set-up of your engine call me I know it looks confusing but once you figure out how it works it's really not.......

[Ron V]

Bill,

Thanks. I actually got it figured out today with the help of my uncle, who is OMC certified. What he was saying on the phone the other day was that you had to mess with the screw up by the ignition linkage in order to adjust the idle. He had meant the screw NEAR the linkage, not THE linkage, and I had misunderstood him. It was only idling about 800 rpm out of gear and barely 600 in gear. Plus the stop screw was not even really resting against the stop, so I think the spark advance was wandering around a little too. I bumped it up a little to where it idles around 900 in neutral and about 700 in gear.

We set the timing last year after the linkage fell apart. Once we reset it, we put a locknut on it AND epoxied it so it couldn't come apart again. I made sure the carbs were synchronized, but have never touched the linkage that opens them. No need to. I know they close all the way and at WOT the pins in the shafts are perfectly vertical. Everything looks like it works fine so I think I'm all set.

It just seemed to be idling a little slow and erratic. I think the fact that the stop screw wasn't against the stop had more to do with it than anything. Took it out and ran it and it idles better and just a hair faster now.

Everything else about the motor is perfectly healthy.

Thanks again.