40hp Big Twin Popping problem

[rennen]

Ok guys and gals,

Stats:
1963, 40hp, Evinrude Lark, Selectric Shift

Already completed:
Points (omc), Condensers, Coils, Water pump, Plugs, Wires, Carb rebuild w/float, New needle with packing. New prop, and shear pin, and linked and sync

Events happening before problem:
Ran aground shearing shear pin and destroying prop. Checked gears in lower unit and everything is OK. All wiring is good as well.

Problem:
This damn motor is lean popping like a mother @^$&#*. Or at least that is what it sounds like. I found the high speed needle (or low, I cant remember, whatever one is adjustable) down in the pan, out of the Carb about a month ago. After replacing it and all the packing around it, I went to go adjust the carbs. She wasn’t having it. It ran too rich, then to lean… I couldn’t find the sweet spot. It would just run really fast (BTW I have no tach) or stall out. When I adjust the carbs to a really fast idle, the motor pops and pops…

Suggestions?
First off, I know I need a tach. But there has to be something that I am overlooking. Should I pull that carb off again and check to see if some of the original packing got lost in there. Or maybe the float got mis-aligned…

I don’t know but I want to enjoy this season, and this motor is not working with me very much. Not to mention (as I am sure you all know) every mechanic in town is weeks out in work, so It is either I use trusty iBoats to help me help myself, or wait another year…

Thanks in advance

 

[DJ]

Re: 40hp Big Twin Popping problem

It is very possible you sheared the flywheel key. Thus, your timing is way off.

Pull the flywheel, if you did, you'll see it.

 

[jimmbo]

Re: 40hp Big Twin Popping problem

Check your model #, 1963 motors had fixed high speed jets, well at least my dads was. Here's what the old owners manual basicly said; Intial setting of the Hi speed needle( along the bottom fuel bowl) is 3/4 turn open from gently seated. Run engine at fast idle until warm then got to WOT, adjust needle for highest speed, return to idle, adjust idle needle( initial setting 1 turn out from gently seated) for best idle, the recheck hi speed needle again.
Is fuel spitting back out of the carb while running?

 

[rennen]

Re: 40hp Big Twin Popping problem

Djohns: Good thinking... I havent pulled the flywheel since the accident. But you better believe that I will tomorrow!

Jimbo: I havent touched my high speed then. (i was referring to the low speed adjustable needle) No fuel looks to be coming back out of the carb. If it did what would i be looking for? Just wetness around the choke butterfly?

 

[jimmbo]

Re: 40hp Big Twin Popping problem

I was asking that because that is one way of checking for a broken or missing reed valve. Quite often when a reed is broken or missing fuel will be expelled out the front of the carb, either like a fog or blobs of fuel. In reality it will richer than normal because the venturi doesn't care which way the air passes through it and will add fuel. On an engine that shares the carb with more than 1 cylinder, it might not be so easy to see since one crankcase will be inhaling whilst the othe is spitting. .