1963 Lark 40 hp - ran great then no go - flooded?

march

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I have a 63 Lark 40 that we've been plugging away at for a while now, and finally got running last week. I ran great on earmuffs in the driveway, and when I brought it up to the lake started in the water with a touch of the key. Went for a tour, motor worked great at all speed ranges, no hesitation, everything perfect. Went for about 15 minute tour, then in for lunch. After lunch the boat would not fire up. Cranked it for a while, tried choke on/off, pulled fuel line at carb, lots of fuel, pulled a plug, it looked a bit wet. Finally gave up on it but I want to try it this weekend.

Does it sound like the motor could simply have been flooded? If so will leaving it sit for a week clear it up or do I need to pull the plugs (which I'd like to avoid since I had to put a helicoil in the top cylinder).

If it is just flooded how do I avoid this happening in the future? Should the choke on the motor always be on the "automatic" setting?

tia

Marc.
 

CATransplant

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

Could be any of several things, actually. Yes, it could be flooded, but please check for spark first.

If you've had the flywheel off, and didn't torque it to specs, it may have sheared the crankshaft key. It has happened to a lot of folks. Then engine will run fine, then you shut it off and it won't start.

When it wouldn't start, did it ever try to fire when you cranked it?
 

march

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

Yes it looked like it was trying to fire, there was a bit of smoke in the exhaust and it actually caught one time, for a second, then died.
 

CATransplant

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

During the time that it was running, did it ever cough or sneeze hard? That's a symptom of a condition that can shear a flywheel key.

When you were trying to start it again, did it backfire at all or blow back through the carburetor. Another symptom of a sheared key.

It could still just be flooded, but that usually clears eventually, unless your carb float needle and seat are stuck open. If that's the case, you'd probably see visible fuel in the carburetor throat.

The big twins like yours are a little prone to shearing keys, if they're not torqued down properly or if the crankshaft taper and the mating flywheel taper aren't clean, or if the key was installed improperly.

Again, has the flywheel been off that engine recently? This happened to me on my first outing with my big twin, and I learned well from it.
 

march

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

no major cough/sneeze, no backfire etc. Hopefully it's just flooded but if it is the flywheel key is it a big job to fix?

tks Marc.
 

CATransplant

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

It's not a terrible job, but you will have to have a harmonic balancer puller (auto parts store), a torque wrench, and some way to hold the flywheel while you do and undo the big nut.

Here's the deal. Try starting the engine in a barrel, since it's had time to not be flooded. If it starts and runs, then it's not the flywheel key.

Early models of that engine had a viewing port in the flywheel, with a little cover held on by two screws. At some point, they dropped that feature, due to cracked flywheels, but it lets you see the points. It's possible to check for a sheared key that has messed up the ignition timing by opening that port and turning the flywheel until the flywheel key lines up with the point cam follower. The points should be fully open at that point. I don't know if yours has the port or not. You have to remove the recoil starter to check (three screws).

I'd run down the possibility that it's just flooded first, but do check for spark before you do that. If there's no spark, then you have another issue to check before the carburetor stuff.

Just out of curiosity, what work have you done to this outboard? That might give us a clue.
 

march

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

So far:

- clean carb
- points/condensor
- starter solenoid
- battery
- starter
- lower unit seals (but I think based on my short test run the LU is still leaking)
- replaced one of the electric shift wires which was broken preventing reverse
 

march

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

...also replaced the water impeller....

thanks for your advice so far....

Marc.
 

CATransplant

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Re: 1963 Lark 40 hp - ran great then no go - flooded?

OK, if you've replaced the points and condenser, that means the flywheel was removed. Did you do the job, or did someone else do it? I'm guessing that, since you asked whether it was hard to remove the flywheel, that someone else did it.

If whoever did didn't get the nut on the crankshaft torqued to 105 ft-lb, then it's very likely that the key has sheared, which would cause the problems you mentioned, including the partial start.

The wet plugs don't mean a lot, since they'd be wet if there was no spark at the right time.

I could be wrong, of course, but check with whoever had the flywheel off and ask if they torqued the nut to 105 lb. It's not that easy to do, and anyone would remember if they did it. My shoulder hurt for a couple of days.

Sadly, there's no sure way to check for a sheared key without pulling the flywheel. I'm almost certain that that model didn't have the port in the flywheel. The whole job just takes an hour or so, once you have all the parts assembled.
 
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