Evinrude 40 hp Lark IV 1962

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benjaminok

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Dec 30, 2006
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Hello all!

Thanks for this nice board which already has given me a lot of usefull information.

Well i have an Evinrude Lark IV 40 hp from 1962 which i try to bring back to life. (I also do have a 1969 Big Twin which almost looks identical "not in mint condition")

The problem is that i can only get the engine startet when i apply full throttle. It starts and runs for around 8-20 sec before it dies. It CAN NOT idle at all and runs only with a lot of throttle...
At the moment i try to bring her back to life with the carb from the Big Twin as i know that this engine did run 1 year ago. Let me say at once, the Big Twin behaves the same way with this carb, so i will try to use the original carb (high & low speed needle adjustable).
I think the problem is that the carb floods as exessive gasoline runs out of the carb when the engine "dies".
I am going to give both carbs a kit (anyone knows a place where to get a kit expecially for the 62??...must be on the internet as I am in Europe).

I have done a compression check which gives me 92 PSI even on both cylinders. Is this to low?

Both plugs give spark, close to 1/4 maby a little less. I think able to start & run the engine indicates that the coils are OK for now?

Anyone with useful hints how to remove the flywheel nut, as 105 is quite a lot? Can´t really get a grip on that flywheel. My manual does not give my any hints on this one.

Any suggestions on this engine are very appreciated.

Happy new year and all the best! d:)
 
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F_R

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Re: Evinrude 40 hp Lark IV 1962

Pull the fl;ywheel and check the coils. Unless they have already been replaced, they are bad. They are famous for that (get brittle and crack). You might as well do the points/condensers and check the spark plug wires while you are in there.
Use a strap wrench to hold the flywheel. Or just use the gear teeth. You MUST use a 3-bolt type puller with grade 8 bolts to remove the flywheel. Nothing else will do. Don't try to get it off by beating on the nut/shaft. Don't use a jaw type puller that grabs the outside either-it will bend the flywhel. And you MUST reassemble with the flywheel and shaft clean and dry and use a torque wrench to tighten it to 100-105 ft lbs if a 1-1/16" hex nut or 60-65 ft lbs if a 7/8" hex nut. Anything else will destroy the flywheel and shaft.
Compresion sounds OK
For carb kits, and ignition parts, you need go no farther that right here at iboats. You'll have to check with them about shipping.
 
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Chris1956

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Re: Evinrude 40 hp Lark IV 1962

Benjamin, I would start with the carb, as it seems you have spark. You can pull the flywheel and check the coils if after the carb is cleaned, you still have issues.

I would remove, disassemble and clean the carb. The kits should be easy to get, since that model was made for a long time and many many were made. You might get by using the old parts, if you carefully disassemble without breaking the gaskets. You should use a 24::1 oil-gas mix. You should clean (use alcohol and a strip of a business card)and set the points, via the inspection hole in the flywheel. Point gap is .020 Inch, spark plugs are Champion J4C, set at .030 Inch
 
tashasdaddy

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benjaminok

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Re: Evinrude 40 hp Lark IV 1962

Thanks for all the input so far, really appricate your help.
I will start with the carbs and check the points and keep you postet about the results.
I can still pull the flywheel afterwards, will need to get a harmonic balancer pully before touching that flywheel.

@ Chris: 24:1 seems like a lot of oil, anyway will follow your advice.
Furthermore I am using NGK B8S at the moment, should be OK according to this:

http://www.psepmarineparts.biz/store/evinrude_johnson_ngk_plug.htm

Think i might try to get some NGK B7S at least according to this cross reference the right plug:

http://www.spark-plugs.co.uk/pages/technical/champion860-n288.htm

Which Champion plug would you guys recommend as J4J to my best knowlegde is N/A...

Will keep you postet.

Best regards!
 
JB

JB

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Re: Evinrude 40 hp Lark IV 1962

Use Champion J4C, Ben. It is the same plug updated from J4J. Gap is .030" to .040"; .030" for variable operation, .040" for slow speeds and trolling.

The NGK are good plugs, but all OMC engines were designed to use Champion plugs.
 
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Chris1956

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Re: Evinrude 40 hp Lark IV 1962

Ben, It may be possible to run that motor on a 50::1 mix, but it depends on the internal bearings, and I have no detailed knowledge on this. Evinrude put out a bulletin stating that "all motors before 1964 should use a 24::1 gas-oil mix", however, I know there are some exceptions to this rule, and your motor may be one of them.
 
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F_R

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Re: Evinrude 40 hp Lark IV 1962

This is what Johnson said as of 1974. Your Lark is same as a RK-24 Johnson. Decide for yourself what you want to do.
1973johnsonfuelmixchart.jpg
 
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benjaminok

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Re: Evinrude 40 hp Lark IV 1962

Well i see the oil mixture rate is a question of believe on this one d:)
Anyway tried the original carb (the one with high & low speed needle) and it acutally got worse. Was able to start the engine once at full throttle and afterwards nothing. The float was looking very bad, i think it is flooding.
Have now ordered some tune up parts which i guess i will receive next week.
Will give the Lark new points, coils, condenser, spark plug cables, plugs and a nice carb rebuild & kit & new impeller.
Think this should help.

Thanks for all you input so far, will keep you postet!
 
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benjaminok

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Re: Evinrude 40 hp Lark IV 1962

Hey all!

Well, well, well...what a day.
Startet to remove the lower unit of the Lark....which was ****. The bolts are really in a bad condition..letting them soak giving them heat...anyway 2 bolts holding the lower unit broke of flush. bummer! Furthermore one bolt of exhaust port cover? (tiny cover in front of gear shift link) went the same way. :devil:
The gearoil looked nice without any signs of water or metal.
However i have decided to give the 1969 big twin a try with the compression gauge which gave me
112 PSI
118 PSI
Now i am unsure wether i should concentrate on that unit instead as compression seems to be a whole lot better. Furthermore it seems to me that it has been better maintenanced enginewise...powerhead looks clean and good with new gaskets etc and in good condition, all bolts came of just smooth.
The Big Twin is a short shaft model and the Lark has an extention between lower unit and exhaust housing. (what i need is a short shaft model!)
Would it be possible to interchange the lower unit of the Lark 62 with the lower unit of the Big Twin 69 as this gearcase is totally corroded and has a small hole into the gearcase. I was thinking of taking the short driveshaft and mount it on the other gearcase. Is that possible without dismanteling the whole gearcase?

Furthermore and very important...does anyone know which bolts i need to pull the flywheel? have finally found a harmonic balancer puller (not easy over here) and am now looking for the right bolts.. which is not going to be easy over here either.

But do i need 1/4 " bolts or 5/16" ? have read different threats in different boards and am very confused!

Thanks again....
 
F

F_R

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Re: Evinrude 40 hp Lark IV 1962

Isn't the 62 Lark electric shift and the Big Twin manual shift? Except for those obsticles, things are pretty much interchangeable.

As for the puller bolts, you MUST use heat treated grade 8 bolts or they may break. The 40hp flywheel is one of the most difficult ones to get off. It will come, but you really have to put a lot of pull on it. They are 1/4-20 thread. Being in Denmark, you may find that to be a bit of a problem, but we fussed about metric bolts here for a long time too. (Still do).
 
jimmbo

jimmbo

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Re: Evinrude 40 hp Lark IV 1962

Yes the Lark is the Deluxe version with Electric shift
 
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benjaminok

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Re: Evinrude 40 hp Lark IV 1962

Well will try to get some good bolts...there are a few shops which sell spareparts for tractors & agricultural machinery...they should have them.
As to the gearshift, the 62 Lark IV i have here, comes with manual shift, can´t say why...
Yes i think things will be interchangable, will look further into this matter today.

Thanks for your advices so far!
 
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AHELL

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Evinrude 40 hp Lark IV

Evinrude 40 hp Lark IV

Motor was working decntly. Then it was powerwashed, and now it spits and spudders once it has started. Any ideas what would fix would be great i have training in boat repair so terms are all easy to understand.
 
Knotty1

Knotty1

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Jul 25, 2009
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Re: Evinrude 40 hp Lark IV 1962

Hello everyone. Thanks for all the info so far.
I am totally and completely new to boat motors. I'm fairly knowledgable with automobile engines but this is my first boat/motor.
Has 62 ( I'm guessing) Lark IV Midek #35531 (40hp apparently). Hasn't been run for few years apparently. Looks very clean and intact. Lower drive section was replaced q few years ago.
As I say, I really know nothing. Any guidance is appreciated.
From what I'm reading there's no separate oil reserve... Supposed to use a mix of oil/ gas. In around 24:1???
I really want to try turn this baby over and see if she still goes.
Also, out of water testing?? Garbage can or barrell ok? Also seen, heard of just. Using hose???
Again, ALL help here is greatly appreciated!!!

Thanks!!
 
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tx1961whaler

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