Just bought a used Scarab twin 350mags. boats in great shape but doesn't have any manuel with it. Just wanted some technical advise on routine maintenance and things to look out for.

Thanks

Change oil every 25 to 50 hrs. change drive lube every season/100hrs. Change fuel water seps every season. Change impeller every season. Should be as reliable as possible.

great thanks for the info.

one other question; what range in temperature should i expect the motors to run at?? i know this relies heavily on the accuracy of the gauge but for information purposes lets say the gauges are accurate.

1999 Mpi's have 71 C or 160f thermostats. These can typically run up to +10%.

awesome thanks for the info. reason for asking is i have twins in my scarab and starboard heats right up in about 5-8min after cold start. the other (port) takes quite a while when idling to reach temp. it will finally get there after cruising for about 10min or so. slow tstat on the port motor??

stuck open most likely. Replace both for good measure. Fuel injection likes warmer temps than carb motors.

Make sure you use the correct thermostat. I believe there is a rivet (stainless) inside the thermostat perimeter for passing current through the housing so the ECT signal works correctly.