1988 50 hp, no start after powerhead swap.

[lmuss53]

I bought a 1988 50hp Evinrude to replace the old 76 model in my sig. on my pontoon it had a bad bottom cylinder so I got it cheap and shopped around for a powerhead. I found a running 1991 with a bad midsection and bought the powerhead. I swapped the powerhead and moved all the ignition components from the blown motor to the new one. Compression is 120+ on each cylinder, spark is a hot blue 1/2" on the forum approved tester. I removed and cleaned the carbs and put known good gas in an OMC can on the motor. I pumped the ball up and moved the throttle linkage forward until the carb plates cracked open a bit, and tried to start the motor. I put mixed fuel in a spray bottle and shot a squirting or two in each cylinder as I cranked the motor. I had jumped the solenoid with the battery cables hooked up but no controls hooked up.

The motor will pop as if to try to start and then hit like the timing is too far advanced. I tried to move everything from old motor to new without moving any adjustment. I moved everythjng, stator and base, box, wiring, coils, flywheel, rectifier, and all the wiring. The motor had good spark when everything was moved.

I think I need to do a link and sync but I never have before. I will wait for the forum to respond to make my next move. I did not try too much here because I didn't want to do too much with the motor possibly out of time.

 

[lmuss53]

I have the factory manual for my 76, I will look at the timing procedure in that manual, is there a lot of difference between the 88 timing and the 76?

 

[lmuss53]

Something else I thought of, the coils are color coded, which one is top and which one bottom? I'm almost sure they're right but I would like to be certain.

 

[racerone]

Orange / blue is on the top.

 

[lmuss53]

Thanks racerone, they were backwards. It is running now but I think I need to adjust the linkage still. The first mark on the lever should be on the carb linkage roller with the linkage all the way back against the stop, correct? Pics in a minute.

 

[lmuss53]

The pics show the position as it idles, the video shows it with the linkage rolled forward a bit. I don't want to mess with this until I hear from someone who knows how to do it.

 

[juno pierrat]

looks like you need a link-n-sync, a manual is real helpful for this, that first line should be i middle of roller, idle screw, thumb wheel, and carb roller all related, move one and it effects the others, and try to do it in water or tank so motor has back pressure, but when you get it right those late 80's two cylinders are a great motor.

 

[lmuss53]

So, I pulled the throttle back against the timing/idle stop and adjusted the thumb screw adjuster to bring the cam up until it just doesn't touch the carb linkage. I set the carbs so they crack open at exactly the same time and roll over to just a touch beyond horizontal at wot. The motor starts and idles well, so we have decided a lake test is next. If I pull the plugs now and do a Joe Reeves wot timing test on it can I use the timing setting for my 1976 motor or should I use something different? I read that the wrong wot timing can cost me a piston and want to get this as right as I can before running the engine.

 

[juno pierrat]

after re-reading your first post, i'll try to get right this time, Its a 91" block with 88" ignition, i've a clymer manual(not as good as a correct year service manual) but any way, it has from 1973 thru 1990 spark advance at 19 degrees. well i may not really help because manual stops at 1990 so don't have 91" settings, guess im maybe causing more questions then help, i'll stop now

 

[lmuss53]

That helps Juno, everything on the motor is from the 88 except the rotating aparatus and the block. The settings for the 88 should be right. Thanks for the help.