Perhaps it was an affordable option for the previous owner to solve an issue. Either not realizing or caring what the outcome was. Regardless I would check out to see what they typically come equiped with from the factory and go from there. If I recall Merc use to put the 1.36 drives on 525's and up. You should still be able to prop for the drive you have otherwise get the 1.5 like you said, you'll be much happier. Years ago when I played around with different drives I found the 1.36's robbed power. If you were getting slippage you would be potentially over reving. Doesn't sound like that's an issue. Also be sure and check your engine over. At the very least do all the basics. Timing, plugs, wires, cap and rotor. Be sure and check your timing right away. (very important)

How does the engine sound at an idle and under a load?

Did you buy a standard XR lower? The sportmaster will just slow you down at anything under 80-90mph

There were two things happening here. First thing the X dimension was too high. Which was causing major prop slip out of the hole and even up on plane. I could go from 3000 rpm - 4000 rpm in under 1 second, without seeing any change in speed. The second issue was the gear ratio. I was turning a 26p prop with a 1.27:1 Sportmaster. This is why I was unable to reach the proper WOT. THis engine runs fine and is not the issue.

As far as throwing on a Sportmaster as affordable option, say what? That's a $5000 + lower.... I was able to sell it to a member of OSO for $2k. Which I used to purchase a new SEI Bravo lower and left me $1k in my pocket. So the boat will be back to the way it was when it left the factory.

just curious why would that slow u down? if both were 1.5 ratio whats the differance?

now you got to test props . i say a 23pitch if its stock???

The front of the case is shaped different and it has a much longer skeg.

I am learning as I go.

The Velocity 260 w/496 mag came stock with a labbed 26p Bravo 1. THis was confirmed with a call to Velocity. I have the original prop. 23p would be to small.

it funny i broke my skeg and had a new one welded on and it is longer .i was going to cut it down to size . but i try it frist and it did help from chine walking . it did that real bad when it was broke .so i am leaving it the way it is . now when i have 25gallons of fuel just me in the boat the boat chine walk a little . so now i puting longer trim tabs The Velocity 260 w/496 mag came stock with a labbed 26p Bravo 1 that then would be the prop good luck

There's been heaps of debate on lowers being better than others and some being faster than others.Here's my take from real experience.The sportmaster is a stronger case and the original,not an aftermarket copy.With the skeg,if you were making a lower for a performance boat knowing that performance boaters run aggressive heights(call it the x dimension)and that skeg is used for steering and control would you want it shorter?This applies to drives run at heights to achieve maximum performance.

Good luck with it Bradley.That was a real find and as you put it a "diamond in the rough".

bajabob,
I read this post 3 times and just wondered if your were while you wrote it? LOL...