1971 Evinrude Lark 50hp Carburetor Rebuild - Any help is appreciated!!!!

[Zabbu]

Ok so i went to start up my engine for the season and i've ran into a TON of issues. First I had a short in the electrical (the past owner had a wire going from the battery to NOTHING and shorting the battery out) Then I had discovered the rectifier had some broken wires, replaced that. Now that i have it running, it only runs when i choke it.... So after calling every shop in town they all agree i need to rebuild my carbs.

I've NEVER done anything like this before in my life... I work on computers for a living, but i'd rather pay $50 bucks for the 2 repair kits than 400 for someone to do it for me.

Here is where i'm at now, (Click the image once to go to the photobuck)



These Carbs are Nasty dirty.....

I'm going to begin disassembling them tonight and soaking them in carb cleaner. However i have 3 questions already.

1st - The two golden slow speed needle valves seem to be at different settings, one has 4 threads showing, the other 6? Is there a default setting for this?

and 2nd - i noticed in this thread that he mentions a special tool for removing an item from the carb, do i need to build/get this tool? or will i be fine without. http://forums.iboats.com/showthread.php?t=244013

and lastly, are there any 'warnings' or things i need to be careful of when i take this apart? Springs flying / tensions / etc.?

Thanks again, you guys have always been a big help. I'll post pictures along the way to hopefully help others with this same situation.

 

[F_R]

Re: 1971 Evinrude Lark 50hp Carburetor Rebuild - Any help is appreciated!!!!

1. Screw them in till lightly seated, then back them out about 1 1/2 turns. That will get it started. They will have to be fine tuned for best running at idle, warmed up, on a boat on the lake.

2. A special tool screwdriver is required to get the high speed orifice plugs out without damaging them. It has parallel sides to the blade so it doesn't spread the soft brass jet, sometimes making it impossible to get out. A lot of people try to make their own, some get away with it, some screw up the jet and/or carburetor bowl. The tool is part number 317002 from any Evinrude dealer. You decide if you want to buy it or whatever. I might add that those orifices MUST be absolutely, positively, shiny squeeky CLEAN!! If not, it won't run right and may even destroy the powerhead.

 

[Zabbu]

Re: 1971 Evinrude Lark 50hp Carburetor Rebuild - Any help is appreciated!!!!

Thanks a ton F_R i'll get with my OMC dealer tomorrow and see if they sell that tool.

I have a question for the forum moderator - I went ahead and purchased the service manual online to be super safe. Would it be against any rules if i took screenshots of the pages that pertain to rebuilding this engines carb and posted them in this thread? I was not able to find them anywhere on the web and feel this could be helpful to others. If you give me the green light i'll go ahead and do so

 

[Zabbu]

Re: 1971 Evinrude Lark 50hp Carburetor Rebuild - Any help is appreciated!!!!

1. Screw them in till lightly seated, then back them out about 1 1/2 turns. That will get it started. They will have to be fine tuned for best running at idle, warmed up, on a boat on the lake.

2. A special tool screwdriver is required to get the high speed orifice plugs out without damaging them. It has parallel sides to the blade so it doesn't spread the soft brass jet, sometimes making it impossible to get out. A lot of people try to make their own, some get away with it, some screw up the jet and/or carburetor bowl. The tool is part number 317002 from any Evinrude dealer. You decide if you want to buy it or whatever. I might add that those orifices MUST be absolutely, positively, shiny squeeky CLEAN!! If not, it won't run right and may even destroy the powerhead.

So no one had the special tool nearby & i'm not that good at grinding down a screwdriver to build my own tool. So I soaked them for quite a while in carb cleaner. I then took a toothbrush to clean all visible areas (resoaking the tooth brush in carb cleaner to keep it clean as well). I then took the can of carb cleaner and sprayed it thorough every port for the high speed orfice. Per a local mechanic - i took a peice of coated steel fishing leader (as to not scratch) and moved it through the valve to knock loose any debris... re-sprayed with carb cleaner... then finally I then took a can of compressed air and blew it out in every direction i could.

I finished rebuilding the carbs this morning and hooked them up to the engine.

http://youtu.be/keFtNRGwXnU

^^^^ thats the video of it running today

Now the only thing left is tuning it a bit, it still isnt running 'smooth' by any means, if i give it gas it seems to 'rev up' real quick almost like a 2 stroke engine does when its running out of fuel.

I checked the fuel filter / screen and it appeared to look fine. I also had changed out a few of the fuel lines.

I hope this is merely some fine tuning and adjusting my low-speed needle appropriately and not an issue where i did fail to clean out the high speed valves properly.