Merc 500 1968 restrictor replacement

[twinx1649]

Hi,
I have a Merc 500S, 1968 model, that I believe the restrictors need to be serviced. The motor stall when I put it in gear. If I do manage to get it to catch when I drop it in gear it runs great until I let idle a long period (approximately 5-10 minutes) which is when it starts to run rough and stall. If I am running the boat and shut it off for 10 minutes it will start up and run fine when put in gear. Any longer than that and it stalls when dropped into gear.

Am I on the right track here? The Serial No. is 2306763.

Thanks for any help.
Jim Mc.

[boats.net]

Run a compression test. Check for air leaks on intake manifold and crankcase halves. Sync and adjust carbs.

[Ski]

Sounds like the idle mixture is too rich and loading up the plugs, do the above suggestions but focus on the carbs. If you want a smoking gun reproduce the fault then swap out the plugs if it immediately runs better then you'd got it.