50hp Mercury 2stroke 4 cylinder Compression Test

[@Benzomat74]

awesome Sound! 4 Cyc Mercurys were the Best. I have the same one with 700 hours+ and it runs and runs !

[@Ken-tr6dl]

For comparison, I have a 1985 Mercury 2-stroke 4 cyl. whose compression on cyls. 1-4 are: 140/137/137/140 and it idles at 840 rpm out of water and 770-80 in water. Setting it lower than 840 causes it to sometimes stall at idle when in water due to normal pressure blow back from exhaust exiting through prop. For me, I find idle settings just right and motor runs like a beast. Sure wish Mercury had put an access hole with a rubber plug on the lower rear engine case to make it easier to get to that bottom spark plug though! Great, very reliable motor if taken care of! Got it mounted on my restored 16 ft. 1968 Starcraft Jupiter aluminum modified v-hull and it pushes it just fine! Fish on!

[@haneysgarage2631]

I agree great motors I used mine for 3 years after doing a full service and new fuel lines ran great and was reliable went to Seattle and back from Evergreen dock in Bremerton several times

[@faronmastin8683]

I'm going after one tomorrow.

[@DCTaylor281]

Hey, just came across your channel. What size/pitch prop are you running to get 37mph?

[@haneysgarage2631]

it was a solas 15 pitch prop and a 13 pitch when I have more people or loaded down

[@DCTaylor281]

@@haneysgarage2631 awesome thanks!

[@emptyjar02]

I have a 76 i believe don't start but cold compression test reads #1, 115 #2 130 #3 130 #4 110

[@emfelling8384]

love the Mercurys good motors

[@robertbuckles3596]

We recently purchased a 1978 Sylvan 16' boat with the exact same outboard motor, a 1983 50hp mercury (same paint/decal graphics, etc). We know NOTHING about it. It does run as the previous owner fired it up for us before we purchased it. I remember when as a kid,,, 40+ year's ago my father had an old Chris Craft boat with a 2 stroke outboard on it. I remember having to turn OFF the motor anytime he needed to change transmission gear direction from forward to reverse or vis-versa from reverse to forward. I am curious, do we need to do the same,,, turn OFF the motor anytime we need to change transmission direction from forward to reverse or vis-versa from reverse to forward with our 1983 50hp Mercury outboard motor? Is it okay to shift the transmission gears with the motor running?

[@haneysgarage2631]

robert buckles it is ok to shift while running if the idle speed is in the specific range for the motor I believe mine was 650 to 750 rpm to be able to shift safely also to tilt motor up it needs to be in gear to lift up unless has a trim pump

[@Anttrice]

Can you tell me how you got your gauge connected to the 4th cylinder. Is there a trick to it?

[@haneysgarage2631]

Anthony Trice when I connected the guage it was very difficult had to Ben the hose and keep threaded fitting straight while trying to start the threads it took a couple times to get it connected

[@tonitoflow3054]

Hi I get the one I’m have problems to crack it on I change the starter

[@haneysgarage2631]

Ya I had swapped out the starter with a new on but it was the starter solenoid