GOOD NEWS. . . . The PICTURE UPLOAD FUNCTION IS WORKING !!! The tech folks at the parent company have been able to remedy the issue. You can upload pictures once again. Thank you for your patience.
You apparently have binding somewhere. Get a manual and do a "Link and sync" which sets up the carbs and the linkage to the throttle control. Otherwise you might have a lot of hours on the engine and time to renew the plastic clips.
I always used a screwdriver sized to adequately fit the slot in the plug. Installed the new fiber washer and with two hands on the screwdriver, got it good and tight. Same for the vent screws you remove to help in draining, and ensuring the LU is full of oil. Never had a problem.
On some Mercs, the little hole in the front of the midsection or LU...forget which is the pickup for the speedometer. Easy to tell as if that's what it is, there will be a small black hose down there and following it up it goes to the Helm with the electrical cabling to operate the speedometer...
I have done that to two engines, 90 and 115 Mercs. All I did was to unscrew the oil pump and remove 1 of its hoses (so that I could pull it back), pull it back, remove the gear/drive shaft...easily removed just grab it and pull) and put things back. left oil in the tank as it wasn't bothering...
Bought a new Johnson 125 HP in 1972 and kept it for 7 years. Kids grew up, no more Sunday outings after church, so I sold the boat. During that time I never did anything, anything, to that engine but put premix in the tank and ran it. Sold it to a friend and he used it for who knows how long...
I started small, forget the dimensions...5/16 maybe and tested for desired effect. Don't remember but I hit the sweet spot the first or second diameter guess.
From earlier in this post: "Some props, like the Merc. Laser II have plugs of different diameters (available) and one that closes off...
Most of not all of my Turning Point Hustler aluminum props for my 90 and 115 engines come ported from the factory....they are designed to mimic SS prop amenities except for the metal and it is a special, high density, aluminum. I get mine right here.
Lubriplate brand grease (in most auto stores) is commonly used in marine environments as it stays put and stays greasy in marine environments.....its white.
Years ago I found a diagram for where to put the holes and how large a diameter. As I recall I found it on here and it was OMC oriented but the process is the same. Using a HF drill press and coated drill bit with a premium cutting oil, I bored out one of my SS props. Took awhile but I...
125F and 142F thermostat opening temps are in my realm of experience. Doesn't take much to pop the TS cover, remove the TS and do a quick check of the validity of your assumption and then put the stat and cover back in/on.
Another thing that surely should be considered is the fuel filter getting clogged with old hose bits and pieces. With the higher speeds requiring a higher fuel consumption rate, a partially blocked fuel filter could be your problem.
I don't know if your engine has a fuel filter or not....my 90...
I "lusted in my heart" (Jimmy Carter) for one of those "Trihedral Hull" babies back in the early 1970's but raising 4 kids came first. We had our water fun but didn't have the rough water capabilities that hull had.
