Help! 1961 Evinrude Problems

This is my 1961 Evinrude on my 1961 Larson motorboat. I just recently acquired the boat. The engine will run and it was running great the first few times I had it out, but it doesn't seem to want to give it anymore. When I put it in forwards and bring it all the way full throttle, it will start to go fast and then slow way down like it has no power. It starts right up pretty much every time, but I'd figure I'd ask my YouTube people what's going on.

Category:

Autos & Vehicles

Tags:

• 1961
• Evinrude
• 40352d
• Big
• Twin
• Larson
• Lapline

[iLongbow]

I've got a 1964 Evinrude starflite 90s and mine was runnin just like that when i got it. It would always sputter and kick it couldn't even push the boat onto plane. All i did was adjust the points, change the wires & plugs but mine is the V4 motor so it has the dual point setup. Now it will push my 17' 35Mph with 5 people on it.

[MCSLegacy]

@iLongbow Wow 35 with 5 people in it? That's crazy! Mine barely hits 20 with 2 people in it! LOL! I'm hoping it's surviving the winter alright. It's out in a cornfield at the moment! I miss it.

[Mr19601965]

look at the top seal on crank

[MCSLegacy]

@Mr19601965 I had it running pretty good by the end of the season last year. It's in storage now. The flywheel ended up popping off the crankshaft and ruining the threads on the crankshaft about mid-season. I didn't tighten the flywheel nut to the correct foot pounds. I think I did about 60 (that's what my manual said), when in all reality it should be 90-110. Did an powerhead swap from a 75. I've got a lot of tuning to do to it this year, probably going to replace the impeller/water pump.

[SilverStarflite]

Former OMC tech here. Ok, its electrical. First thing to replace or check is the spark plugs, from the sounds and symptoms, its running on one cylinder. Those twins were designed to run on one cyl to get you home if one failed. Thats why it starts and runs, but the no power issue is a bad spark. Start there, if that does not solve the issue, then start backwards...plugs first, points second. You said you just got this engine..has it been sitting long?

[MCSLegacy]

@SilverStarflite Thanks for the quick responses! Former owner said they had started it last year, it hasn't been on the water since '94. 1st and 2nd time out it ran great! Decent speed for 5 guys. The flywheel buzzed one of the spark wires and brought it down to only about 2 strands of wire. It was still sparking, but I replaced both wires anyways. Originally I was not getting spark on one cylinder and replaced both coils. Had it out yesterday, but had a dead battery, so no go. Thanks again!

[Jokohs0cks]

a silly question.. you have blended with 2% oil, right?

[GTweed0605]

I have a 1960 model 40HP Lark , sounds like it is missing on one cylinder, change plugs first, if that doesn't correct problem, check spark, it should be a strong blue spark of end of wire to plug, if no spark or spark is yellow, could be a weak coil or points and condensor. I have had to change one of my coils and points/condensors. There are maunuals available on CD on ebay if you need one, I have a copy and it is worth the $5 cost. Good luck.

[TheSchoegglnator]

spark plugs would also be my first guess but the carburetor could also be severely out of adjustment and your mixture in the cylinders could be way too rich at the time of ignition (too much gas not enough air)

[SilverStarflite]

If it were in my shop, Id start with new plugs, check the wires for any rips or cracks (tape them up if so for a quick fix) look at the points to see if they are corroded and or need cleaning...l