Evinrude Ski Twin 33hp knock at mid RPM

[kfa4303]

Re: Evinrude Ski Twin 33hp knock at mid RPM

Hi dj. Glad you got the flywheel off. Here's a great ignition rebuild link with lots of pics. It's for a different model, but all the steps are the same. The little "sponge" is called an oiler wick and it is attached to one of the bases of the points. It provides a small amount of oil to the cam as it spins, but you can live without it.

3 HP Evinrude Lightwin Ignition System Tune-Up 1952-1967

 

[HighTrim]

Re: Evinrude Ski Twin 33hp knock at mid RPM

The condensors are the originals, may have been a problem. With the tune up kit, you should be good to go.

You can see the oil wick in the first picture. Dont leave it out, you may be able to live without it, but the motor wont.

Lets preserve these outboards for our kids and grandkids to enjoy as well, not just ourselves. It only takes 2 seconds to install.

The gap should be 020 when the rubbing block of the points is aligned with the crankshaft/flywheel key. After setting, clean with acetone. A little oil fim from your feeler gauge, even oil from your fingers will limit spark. No need to loosen the hold down screw when adjusting, tighten it then adjust.

Clean the flywheel taper with the acetone as well before installing flywheel and torquing.

 

[djm0]

Re: Evinrude Ski Twin 33hp knock at mid RPM

So I finally took everything apart, cleaned it, put new condensers and points in, set the points to .020, put the flywheel back on aligned to the key and tried starting her up with the muffs on. She fired up like no one's business then just slammed to a stop. I noticed the it was stuck in neutral for some reason and there was no spark. Took the fly wheel off again - this time it took about 10 times to effort and the screw driver is bent like you wouldn't believe.

The crankshaft key broke in two?! I carefully removed the two pieces and but the crank and the flywheel appear okay. What the heck happened!? Thank god the part is cheap but this worries me... Did I put the flywheel back on incorrectly? It fit, followed the groove for the key and tightened it down. Also now that the flywheel is off it shifts fine so its likely that the flywheel dropped perhaps? preventing the linkage from moving?

http://www.**********/parts/search/BRP/EVINRUDE/1968/33852R/CRANKSHAFT GROUP/parts.html

 

[nwcove]

Re: Evinrude Ski Twin 33hp knock at mid RPM

was the key vertical? ( not at the same angle as the taper?) was the taper perfectly clean and free of any burrs....both flywheel and crankshaft? .......did you torque it down to spec??

 

[djm0]

Re: Evinrude Ski Twin 33hp knock at mid RPM

I honestly can't remember how the key was set. I cleaned the crank and flywheel prior to installation. It was torqued to spec. There are a few marks on the crank now... I hope it doesn't affect anything... It looks like nothing is damaged and the marks are above all the components.

The key drives the wheel on these outboards right?

 

[nwcove]

Re: Evinrude Ski Twin 33hp knock at mid RPM

I honestly can't remember how the key was set. I cleaned the crank and flywheel prior to installation. It was torqued to spec. There are a few marks on the crank now... I hope it doesn't affect anything... It looks like nothing is damaged and the marks are above all the components.

The key drives the wheel on these outboards right?

the key does not "drive" the flywheel. the key is for alignment only. the taper on the crank , and the taper in the flywheel make a friction/mechanical fit. you may have to 'lap' both surfaces now to make them mate together properly.

 

[djm0]

Re: Evinrude Ski Twin 33hp knock at mid RPM

Well I have some good news. I installed the new key and cranked up the flywheel to about 105lbs to give her a test run and both cylinders are now firing. I can run with a wire unplugged on either cylinder but the bottom cylinder still seems to me misfiring at low rpm. That "sneeze" sound is pretty clear causing the engine to shake a bit. Its still a lot better then it was mind you.

With new condensers, points and wick installed, a spark clearly happening with my spark tester what else could be causing this? Do I need to do some timing checks? The feeler gauge is fair dead on .020 on the points but I can't seem to make them any future apart as there isn't anymore room to move the point's "mount". Do I need to simply bend it a tad?

Thanks guys!

 

[Big Jay]

Re: Evinrude Ski Twin 33hp knock at mid RPM

You should be able to "shove" gently but firmly the bottom of the points base with a flathead screwdriver wrapped in a rag, make sure you put slack on the adjuster screw first to make room to push it over. I read in another thread somewhere here that "new" points should be set to .022 instead on .020, so I tried it and it seems to have made a world of difference in my spark strength and distance that it could jump.

Another thought, I couldn't get my BigTwin to stop it's lean sneeze either, so on the advice of yet another thread I found here I installed an extra packing washer which enabled me to tighten my SS needle further,creating a tighter seal. That seems to have fixed it. I would make sure you have the SS needle set right before adding the packing washer tho...

One more thought lol....

My 18hp had the same illusive sneeze issue... To fix it, I had to set the HS needle. Simple as that... once it was set, the SS needle was a cinch to set and it fixed my sneeze completely. I had to take it out on the water and go full throttle and slowly adjust the HS needle "out" to it's highest RPM, once that was done I started turning it back in until I noticed a loss in performance, turned it back out an 8th and tightened it down. I as then able to idle in gear and adjust the SS needle in. As I went the rpm's rose a bit then I caught a sneeze or 2 so I again backed it out about an 8th and all has been well since. I make the odd adjustment, but not much ...

Hope this helps!

This is just my experience, so if anyone has criticism I'd love to hear and learn from it!!

Big J

 

[Big Jay]

Re: Evinrude Ski Twin 33hp knock at mid RPM

Sorry