1965 Evinrude Lark 40hp surges at high speed

Hey all,

I am new to the forum... I've been reading a lot of posts and there is some great knowledge on here.

Here's my story. I have an 1965 Lark VII 40hp. We bought it last year, and it has given us some trouble, but has never failed us (knock on wood).

Ever since we got it, it would run fine at low speeds, but once we get a little above 1/2 throttle, it would start kicking between high and low(surging I think is the correct term). One day we were looking at it with the outboard cover off, and decided to start it up.... what do you know, It worked great. We assumed it had something to do with the carb not getting enough air or something, but this was disproven by trying to run the engine with the flap on the cover open, and still not working.

So one night, when it was dark with the cover on, we noticed the front of the cover where it contacts the bottom part of the motor(I can post a picture) was sparking!!! So I was thinking that the plug wires were shorting out on the cover... got the plug boots replaced, and taped the wires up... still doesn't help. I also tried to tape up a couple of the metal parts of the engine that I thought were contacting the cover, no luck. Also, isn't the cover fiberglass?

Anybody have any insight into this? It is a pain (and really loud) to take the cover off anytime that we go sort of fast. I can provide more detail and post pics as needed. I appreciate all of your help.

Happy boating!

Re: 1965 Evinrude Lark 40hp surges at high speed

well you obviously have something shorting out. at 40 years old there is obviously cracked insulation some where on the wiring. inspect all the wires. a kill wire could be grounding out one of the coils.

Re: 1965 Evinrude Lark 40hp surges at high speed

It is kind of common for one of the spark plug wires to arc through where they are clamped to the mag plate. Impossible to tell without tearing it down, unclamping it and looking for a tiny pin hole through the insulation. Once you've gone that far, you might as well put new wires in it. Use only "wire" wires with copper core. Don't use car wire with that string core stuff.

Re: 1965 Evinrude Lark 40hp surges at high speed

I was guessing it was something like this. I have to remove the flywheel to get to the mag plate, correct? I tried tearing it apart last season to check those connections, but I didn't have the proper tool to remove the flywheel.

Re: 1965 Evinrude Lark 40hp surges at high speed

i just did my 58 35hp, $136 for complete job and impeller, laingsoutboards.com it's easy to do, youcn remove the timer plate and turn it over to get to the clamps that hold the wires, then use the long screws to first reattach the plate to the bearings, then insert the short screws, took me 30 minutes to realize that. i can now do it all in 20 to 30 minutes. be sure to use #8 14/20 bolts to go into flywheel , regular hardware store bolt will strip off in the flywheel, leaving the threads.

http://forums.iboats.com/showthread.php?t=181688

Re: 1965 Evinrude Lark 40hp surges at high speed

So when I remove the flywheel, what is below it? Are the coils right below? What else gets replaced?

Can you give me the two-minute rundown of the evinrude ignition system or direct me to a good source? I haven't done any engine work, besides mess around with this thing. Also, what does the impeller do? something to do with cooling?

Thanks again

Re: 1965 Evinrude Lark 40hp surges at high speed

If you intend to do the work you should get a repair manual.You can get an
aftermarket one here.A factory reprint at ken cook.com.You could also try the library.If you have never worked on a motor you may want to think it over unless you are mechanically inclined.The ignition is quite simple,similar to lawn mower motors of the same time frame.Basically the flwheel magnets generate low voltage that is released by the points points as they open and the coils create the high voltage.
If you run it in the dark you may see the arking spark.You could replace the plug wires just cause they are probably real old.There is also a slim possibility that there is an exhaust leak that gets trapped under the hood but this usually affects all speeds.Don't attempt any repair without the manual.
The impeller is the actual cooling pump.If you don't know its condition change it.

Re: 1965 Evinrude Lark 40hp surges at high speed

i sent you a email with instruction, but find a friend with a little experience with atleast lawn mowers. the impeller is the rubber fan in the water pump that makes the water flow. get the top done, then lets worry about the bottom you can order the kit for the impeller at the same time to save shipping.

i personally use for parts http://www.laingsoutboards.com/newp...ncludes Gale, Sea King up to 1963, and others