I put a 2010 mb 35 hd mini on a 2006 excel 1754 125ga was only running 12 mph at 3850rpm's it was plowing the motor has twin pipes. I thought it should run atleast 20-25 with one person. I mounted the motor in the same place where the 45hd that was on it. I had a 1752 100ga with this motor on it and could 28 mph. Any help will be great.

Check prop?

got some wear but not to much I just took the motor off one boat put on the other boat. If it ran good onthe other boat should it not run ok on this boat?

Does the motor match the transom height?

transom height and angle.....if you can tell there is wear on the prop you are loosing speed. check bottom of boat its not performing on....sounds like a hook at the transom.

Yea both boats are tall transom. Its almost like I'm dragging the anchor it never really plained off. No hooks are anything boats slick. Tried moving weight around didn't help.

If you were performing good yesterday on the old boat, & the ONLY thing you did was pull the motor & mount it on the new boat, but now it won't perform, new boat either has a hook, transom height doesn't match, or the flotation is so waterlogged it's overweight.
On the other hand, if the old boat was really light weight, you could have leaking valves & just didn't notice because of light load.
1st thing to check, get a long straight edge & hold against the bottom of the hull & make sure there's no hook. Next,double check the transom height. If both are right, do a leak down test on motor. I'm betting on hook.

Double checked the transom its good , checked for hooks with a 4ft level no hooks, I wound't think that the foam is soaked its been kept in a shop unless the boat was in the water. The foam was my first thought I cut what I could get to and it was dry. I guess valves ?

Another thing to think about is your prop, but checking valve lash is free. Also have a leak down test done.

Something's not adding up, there's got to be a missing piece to this puzzle.

leak down test done where can I get that done I live in northwest Al none of the mb dealers know anything over here. I checked the prop outside to outside is 11 3/4

You need a new prop. 1/2" is a lot of wear on these.
Any Briggs & Stratton shop should be able to do a leak down test, or you could go to a Harbor Freight & buy the kit to do it yourself for about $40

so i guess if I have valve problems I guess it would best to go ahead and get new setx heads. Also do you know the easiest way to get the foam out of the floor. thanks CAMO

If the valves are leaking, the only way to fix it is a valve job. Since you've already got em off, might as well go the extra mile & get heads worked to.
No easy way to get foam out of Excel that I know of. Good luck on that one.

Camo what about the super liner how did you get yours off? I figure out how to take the floor out. Just need a tip on the liner. thanks for all your help..

I never had an Excel