1960 lark 2 40 horse problems (updated w/pic)

[bashr52]

I just aquired a boat with a lark 2 40hp. I read the reviving an outboard thread (been sitting in a garage for about 20yrs), and have replaced the plugs, impeller, lower unit oil, carb rebuild (hight speed out one turn, low 1.5), and verified I have nice blue spark and a working fuel pump. The damn thing wont start though. With the throttle in the start position, the mercury switch trips so you cant crank it. Leaving the throttle at idle, you can get it to pop and sputter like its trying to start, and then will die off and just crank. Occationally there will be one singe pop out the exhaust that will force water out of my test tub. It seems to me like the timing is off. Plug wires are in the correct order as well. Spraying gas into carb will let it try and start until it burns off, but then dies off again. Whats the procedure to verify timing is as it should be? Those with the same engine, where does the throttle have to be to start, and whats your procedure? Bulb pumps up solid and holds pressure (new).

 

[1946Zephyr]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

yea, it sounds like your plug wires are crossed. The easy way to tell is follow the spark plug lead from the front most coil and make sure it goes to the top cylinder.

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Thats what I thought too, only the one is marked "top" and they are fastened in such a way that they are only long enough to go to one plug.

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Just tried to remove the flywheel to check everyhtong out underneith. Removed center nut and washer, attached flywheel puller, and actually bent the flywheel trying to get it off. It still wont budge. Ideas?

 

[rolmops]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

What you attached was probably a gear puller,which you attached to the outside.Try a harmonic balancer that is normally used to pull a steering wheel .Once you have it off,replace the bent flywheel with a straight one because yours is no longer balanced.And please do buy a manual.It is under $50 and a flywheel costs a bit more.

 

[tmcalavy]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

The timing is fixed...a woodruff key in the crankshaft aligns with a notch inside the hub of the flywheel...make sure taper of the crankshaft and hub of pulley are clean and dry, then torque it down to specs. The flywheel can slip and shear the key if not installed correctly. Get a harmonic balancer puller and three hardened bolts to screw into the flywheel holes...patience, pressure and an occasional wrap on the center puller bolt will get it off. Sometimes when they "give" you will hear a loud pop.

 

[Willyclay]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

If you need a service manual, send me a Private Message with your email address and I will send you a scanned copy of a non-factory service manual that covers all 30-40HP motors built by OMC from 1956-1964. Good luck!

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

I took the flywheel puller, snugged it up, whacked the center with a hammer, snuged it again, and wacked it again and it popped right off. I replaced both condensors, and the bottom plug is getting awesome spark every rotation, it appears the top one comes and goes. Trying to track down two new magnetos locally but so far everyone says they have to order them.

 

[tmcalavy]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

That's a good motor. If you're going to keep and run it, and why not right?, you can replace both coils/points/condensors/plug wires for less than $125...probably can get all that in the Iboats mall. If the plug wires show any wear at all, replace them with solid-wire core wire from a small engine shop. Set the throttle, tiller or remote, to Start...but there is always some slop so watch for the cam plate under the stator/magneto to contact the top carb roller just a bit...that's Start position. Make sure the stator plate and throttle linkage are clean and lubed. Choke should be on/out when you start it, then let it run awhile and ease the choke off. Sounds like you're making progress. If you need a flywheel, try the free classifieds at www.aomci.org

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Ok I found someone local (within 30 min) of me with the stuff. Picked up all the tune up parts while I was there. Just replaced them all, but I think I got the cam/magneto assembly hooked up wrong. While cranking the plate moves back and forth easily. you can see the plug wires moving back and forth as the cam plate rotates. Seems like there should be a spring or something holding the assembly tight? It all works as it should when the throttle is advanced, but is free to spin a few degrees either way? Good news is I get good spark at both plugs now, but with the timing alternating like that, it wone start.

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

If you need a service manual, send me a Private Message with your email address and I will send you a scanned copy of a non-factory service manual that covers all 30-40HP motors built by OMC from 1956-1964. Good luck!

pm sent

 

[F_R]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Ok I found someone local (within 30 min) of me with the stuff. Picked up all the tune up parts while I was there. Just replaced them all, but I think I got the cam/magneto assembly hooked up wrong. While cranking the plate moves back and forth easily. you can see the plug wires moving back and forth as the cam plate rotates. Seems like there should be a spring or something holding the assembly tight? It all works as it should when the throttle is advanced, but is free to spin a few degrees either way? Good news is I get good spark at both plugs now, but with the timing alternating like that, it wone start.

The coils are probably dragging on the flywheel. Did you adjust them flush with the posts they sit on? Oh, and didn't you say you bent the flywheel? That will do it too. You do know that damaged flywheel is dangerous and can kill you, don't you?

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

One magneto was dragging. Flywheel did not bend, it was starting to deform a little when I was pulling it, but backed off before damage was done. Its running now, but will occationally idle down/pop itself out, I think it just needs to be run and loosen everything up inside after sitting for so long.

 

[tmcalavy]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Read the Top Secret file at the top of this forum...check your carb adjustments.

 

[bashr52]

Re: 1960 lark 2 40 horse problems (update after open water test)

Re: 1960 lark 2 40 horse problems (update after open water test)

OK this morning I did a linc and sync adjustment as per the manual. Decided to take it out today to let it run at higher RPMS's and get some fresh gas/sea foam worked around in the system. Fired right up, put it in gear, and gave it throttle. It was bogging like crazy, did not increase in RPM much and was smoking. So I had my buddy drive while I popped the cover, and started leaning it out. As I leaned the high speed circuit, the thing began performing, and pretty soon I had found the best mixture, and we were up on plain and hauling ***! We made a big loop at 3/4 to full throttle, and then I knocked the catch loose on the gas line to the engine and we ran it dry and stalled it. After that, it would not fire again until I richened up the mixture to get enough gas to the low speed circuit. It will not run under the start position at all. Finally got it strated again (in gear) and before it died I gave it throttle and leaned it again. We were running along good and then the lower cylinder lost all spark and we were running on just the top.

I did pull the top plug and check it, and it was a nice golden brown so that mixture setting was right on. Anyone have ideas on whats up with my carb/timing below the start throttle position, and why when the high speed circuit is dialed in it cuts out fuel to the low speed?

 

[Willyclay]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

I thought I had the carburetor clean on my 1959 Johnson 35 the first two times. However, it took a third cleaning during which I literally pulled some crud out of the low-speed passiage with a pick. A 24-hour soaking is usually needed. The loss of spark on the lower cylinder is probably something simple like the plug wire has worked loose from the coil as that connection is critical. You just have to go through the troubleshooting steps for each problem. When you do get it started/running right again and I know you will, a decarbonization process might be a good idea since the motor is almost 50 years old. Good luck!

 

[tmcalavy]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Or the coil for your lower cylinder is dropping out under load/heat...they do that. If those are orginal coils, change them...cheap insurance to get the best from your motor. Might also update/change the plug wires. Sounds like you leaned the carb out a little much...don't want it screaming at WOT. Find that point, then richen it about 1/8 to 1/4 turn and tighten down the high speed nut. Idle back down and adjust the low speed from 1 and 1/2 turns out to wherever you get the best steady idle...that won't be real smooth with a big twin but you have to have good spark/fire on both cylinders to get there.

 

[bashr52]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

I Just replaced both points/coils so I'm hoping one didnt go bad. Going to troubleshoot it some more, and hopefully the wire just pulled loose or something. The engine was stored dry, so no old gas in it, and a good soaking and high pressure blast though all passages proved nice and clear. I added a half bottle of seafoam to the gas, just hoping to get it running long enough to get it all worked through the system. I think once I get the spark thing worked out it will run well enough for me to take it back out and get the carb dialed in.

 

[tmcalavy]

Re: 1960 lark 2 40 horse problems

Re: 1960 lark 2 40 horse problems

Check the plug wires under the stator/mag plate. If you didn't change the plug wires, one may be working loose from the coil or could have a crack/worn spot that allows the spark to ground out rather than go the plug.

 

[bashr52]

1960 lark 2 40 horse (update)

1960 lark 2 40 horse (update)

OK fixed the spark issue. Re-terminated both plug ends, re-crimped the wires to the cut-off switch to poins connection, and tied everything out of the way so it doesn't drag on the flywheel. I can pull start it no problem at the "start setting" and it wil start and run. The ignition switch cut off doesn't work at this setting though, so cranking it will not allow it to start. The thing will run awesome as long as the butterfly on the carb is cracked (above start position) but as soon as the throttle is returned to idle and the carb closes, it won't run. So basicly I can run it at high RPM's but nothing at low. I don;t see any adjustment for the butterfly, so I
m at a loss.