Post a video of the engine running at idle on a hose.----Post a video of smoking with engine at full throttle.-----Note ----there are no " oil control rings " on this 2 stroke engine.------Smoke is normal.----especially at start-up.-----Oil recirculation passages in working order ?
Remove flexplate and look for stain / rust mark to install in proper position.-----Or put #1 at TDC and use timing marks.-------Timing on these motors usually does not go out of adjustment.-----Start with a compression test.-----Post your numbers.
Does choke close and stay closed when you pull the recoil ?----Does spark jump a gap of 3/8" on a test device ?-----Could also be an issue with the reed valves .----Or an issue with crankshaft oil seals.
This is not a hard job to do.------U-tube videos will help you.-------Shop might charge you 2 hrs.-----Or visit ----leroysramblings ------for instructions.-----The bushing for shift rod o-ring can be replaced without removing the bushing.-----Or run a 5/16-NC tap in there for 3 threads and pull...
Perhaps use an oil that smokes less.-----Might cost a little more.-----And do you understand the concept of a 2 stroke and the reason for the smoke ?----When you operate the manual fuel pump does it go hard?-----Is thermostat in place?
Well-----I would now do a compression test.----Post the numbers.-----Does the tell tale hose come off the side of the engine block or off the top ??------Any time you put a " new to you " motor in service it needs a new impeller!
There is a switch on the side of the motor block.----Cuts spark to 3 cylinder for shifting.----Perhaps check it.----Do a compression test as well , post your numbers..----How did it run for you last season ?
Did you unplug the wiring on the VRO?----Unplug the oil tank ?----Did you install a new water pump impeller ?----And you kept running your motor with the alarm sounding ??
If you have a 1956 / 57 / 58 model 7.5 HP you can fit the 6 HP gearcase up to the 79 model year.---Just need to know the tricks.-----Finding a prop for those 7.5 models is easy , if you know where to look.-----The ---aomci-----has a free " wanted " section.----Lots of folks there with the parts !