Upgrading a Honda 50 to a Yamaha 90 2 stroke

[Alan H.]

I ve decided on a Yamaha 90hp 2 stroke to replace a Honda 50 on my 98 X. I've tried to read as much of the posts as I can, but don't get the desired result when I try to do a search. I would be grateful for either answers or links to previous posts that are relevant.

In selecting the prop, the engine guy wants to know the weight. I am going with 3200-3400lbs. Does the unusual hull shape (compared to traditional planing hulls) factor into the selection? Do I get more pitch? I get the motor on Tuesday and need to decide on the prop.

Also, the Honda weighed about 210lbs. The Yamaha 90 2 stroke only weighs 260lbs. I can't find the posts on transom reinforcement from years back. there was a guy who upgraded to a suzuki115 and another to a 135 I think. There was some good posts back then about backing plates and adding support knees to the insde transom.

I'm adding about 50 lbs back there and don't plan on any hole shots or stupid speeds in any kind of chop. what is the consensus on beefing up the transom?

I haven't been to the site here in about two years and I know this topic is probably been covered ad nausium. I just can't seem to pull up a descent search.

Any help?

Alan

[Catigale]

Alan - Ill let the guys who have these motors fill in the details, but you might want to try your search in the 'Performance and Tuning' forum where we kick around ideas on motors and sailing as such...about a year ago we moved most of that discussion over there...

Also, when searching, make sure you click the 'search all terms' button....

Welcome back!!!

[Alan H.]

OK,

My searching skills have improved and I found Mark Prouty's (Billy's) aluminum backing plates. Does anyone know where I can find the pre-made wedges that help with the trim issues?

[beene]

Does anyone know where I can find the pre-made wedges that help with the trim issues?

CLICK HERE

Just one source mind you. I will be mounting a 75 at 350lbs with transom reinforcement and those wedges for trim issue and help with clearing the underside of the seat, if that is at all possible

G

[Alan H.]

Thanks for the help. Got the wedges ordered today from west marine.

I've got 3/8th" thick X 5" wide aluminum for the backing plates on the inboard side of the transom.

Are any of you putting a thin sheet of aluminum between the wedges and the transom to distribute the load?

[Billy]

Alan, don't know if I really needed it, but I installed aluminum plates vertically between the transom and the wedges to distribute the load when I installed the 140 Suzuki. (Just made me feel better.) I also install an aluminum bar horizontally inside the transom (lower bolts). I had concerns about a full power reverse--didn't want to take a chance on pulling the bolts through the transom. After 5 years--no problems. (Total added weight--15 lbs. Added confidence level--priceless.)

I gave Mark Prouty all my measurements and instructions when he installed his 115. Since then my computer crash lost all that info. If you want measurements of the plates, I can get them and forward to you.

Best of Luck.