Setting idle on '78 Evinrude 85

I have a 1978 Evinrude 85 that starts pretty good, seems to take a not unreasonable amount of time to warm up, and runs pretty well at high speed.

It seems to idle lower than it should though, and after it warms up, it doesn't seem to want to idle at all without useing the warm-up lever. Its a little tougher to start once it warms up too.

Messing with the thumbwheel on the throttle cable doesn't really help.

I figure I need to adjust the low-speed needle valve. That leads to my question. Thier aretwo little screw caps on the sides of the carbs that, once removed, reveal little screws inside. Are these the low and high-spead orifice adjustments?

If so, how would I adjust the low speed orififices? Since thier are two (one on each carb), how do I know which one is out of wack when I start adjusting them? Seems it would be easy if their were just one carb, but I'm not sure how yould do this with two. Do I just pick one, mess with it until its as good as it gets, then do the same on the other side?

If these little screws aren't the adjustment I'm looking for, what is?

Re: Setting idle on '78 Evinrude 85

You have all fixed jets on your caburetors. There is nothing to adjust.

As the pistons rise and fall, they create a rhythmic vacuum behind the reeds, which open and close, thus pulling fuel and air mix through the carburetors. Crossflow carburetors deliver a precise mixture of air and gasoline using fixed orifices, sometimes referred to as jets.

When the carburetor throttle plates are closed at idle, the vacuum places greater suction on the carburetor throat behind the throttle plates, pulling fuel through the idle orifices and into the throats of the carburetors through tiny openings in the floor of the throats.

Whenever the carburetors are moved, as when cleaning, or for whatever reason, it is required that they be replaced airtight to prevent upsetting the delicate mixture of air and gasoline, so new gaskets should always be used.

Additionally, the carburetors must be synchronized so that they open and close at precisely the same time. The throttle plates should be fully closed at idle and perfectly horizontal at WOT (Wide Open Throttle). The importance of these steps can never be overstated because it is impossible for the engine to run smoothly without them, especially at idle speed.

The synchronization of the carburetors requires two steps: first the individual carburetors have to be synchronized with each other; then the carburetor linkage has to be adjusted so that the roller of the cam follower aligns precisely with the embossed mark on the throttle cam while almost touching the cam. Any attempts to adjust these settings other than directly on the carburetors? linkage will usually only make things worse. The throttle cable should be disconnected while making these adjustments.

Once the carburetors are perfectly synchronized and the roller set to the embossed mark on the cam, the throttle cable should be adjusted so that it slips on without causing any movement of the linkage at the engine. To allow for tension, move the throttle arm on the remote control fully forward and back to neutral before adjusting the cable. If you have a warm up lever, it should be down (off) when the adjustment is made.

Re: Setting idle on '78 Evinrude 85

so there is no way to raise the idle speed?

It seems that if it were just a tad higher all would be better. When the warm up lever is less than a quarter of the way up, it runs at what to my ears seems like a decent idle. Isn't there some way to get it to run that fast when the lever is down?

Plus, not having a tach, how do I know if it is fast enough? Is their a way to hook a tach to this motor, and if so, what rpm is proper for idle when warmed up?

Re: Setting idle on '78 Evinrude 85

Once you have the carburetors set up properly, the roller alignment with the cam will have you very close to the correct idle.

You set the final idle adjustment on the water, in gear, unrestrained with a target of 650 RPM.

Your main engine harness is pre-wired for a universal tachometer that can be set to a 6p setting. You need the gray signal wire, a purple positive and a black negative. The purple and black wires are normally connected at the ignition.

Beginning in 1978, some remote controls have a 3 wire plug below the ignition key for the tachometer. Similar to:
http://www.maxrules.com/graphics/omc_pics/REMCONTBOX.jpg

Re: Setting idle on '78 Evinrude 85

Ha! Thats what that little plug is for! Thanks!

Re: Setting idle on '78 Evinrude 85

but back to idle adjustment, once I have it synced, and the cam right, how do I do this on the water adjustment? What do I adjust?

I live in an apartment that for various reason makes out of the water engine running impractical, so I do all this stuff on the lake anyway.