So I changed the raw water pump, serviced the stern drive (gear lube), replaced the plugs (the old plugs looked good, no funny color, etc.). I noticed that my vacuum choke on the carb will not open fully when the motor is warm, when I manually opened it, the engine smoothed out. No vacuum leaks that I could find, so that means possible low compression? Can a partially closed choke could cause a WOT back-fire? Think I?ll put an electric choke on. NOTE: I did not get a chance to check the timing yet.
So, I completed a dry compression check (cold motor).
Compression as follows (PSI):
1 - 110
3 - 110
5 - 105
7 - 105
2 - 105
4 - 105
6 - 105
8 - 110
So I guess this means the little motor is worn out? So my next question, how can I get a couple more years out of her? Is there a timing adjustment, miracle additive, etc? Nothing leaks and this boat has been well cared for. Also, another question, should I have warmed the motor up before the compression test? I did not complete a wet compression test, I assume compression readings would have been better if I had.
As usual, thanks for all the help!