Re: Motor upgrade
First off: I would guess the 150 is about 50-75pounds heavier than the 125. You have one more cylinder and crank and the exhaust cover is way more massive to accommodate the tuned ports. The cowl is way bigger too. Fuel usage: At full throttle expect to use about 15 gallons per hour.
HOWEVER: The `150 WILL make the 125 look sick. I never liked the 5 cylinder 150---until I bought one. It converted me. I had a 125 on my 21 foot cuddy. It topped out at 33 MPH. The 150 will top out at 41-43 MPH. A significant difference and hole shot is much faster.
Now, to your trim. While you are trying to repair the trim, you can put two 2 or 3 inch long 1/2 inch diameter bolts through the approximate correct holes in the transom clamps. Use a 1/2 inch coupler--looks like a 2 inch long nut-- on the inside of the clamps. This will keep the engine from dropping all the way while running. At least that way you can see top speed without plowing.
If the engine pushes the trim ram all the way in while under power, the check valve probably has a bad O-ring. Typically the front check valve goes bad before the rear. Thus, if you have the pump with the screw-in check valves, you can usually swap the rear to the front and the trim will work again for a while. Later on, you can replace the tiny O-rings.
I suspect though, from the age of your 125 white Force-- 85-86- I think 84 was still Chrysler. Anyway, I suspect that the pump has check valves held in by internal circlips. These valves are not repairable and I don't know where to buy replacements. Your best bet would be to buy another complete pump.
Since both trim and tilt cylinders are on the same hydraulic circuit, IF the tilt cylinder has a bad piston O-ring, the engine will also drop like a rock. To test for this, you block the port to the trim cylinder and raise the engine. If it drops quickly, then there is a good chance that the tilt cylinder O-ring is bad.
