Really confused and need help

[Jig N Pig]

I have a 21ss extrene 2001 stratos boat. Powering with a 2008 225 HP HO evinrude etec. I have always had a lightning gearcase until now and i replaced it with the magnum 1.

Before replacing the lower unit i could get 70 - 72 MPH at 5800 RPM. Now with the magnum (which is a lot different.) I have not been able to do anything near what should be happening. I am running a 24" raker and have for 20 years. It has 3 holes drilled in it ( croxton) and i have always had one small PVS plug and one medium PVS plug in. Now with the lower unit change all it wants to do is blow out.
I have had it raised to 3 1/2 " below pad all the way down to 7 " below pad, Right now it is 4" below pad and has 2 holes plugged. I can only get 50 MPH and it runs at 6000 RPM.
Seems like I have extreme bow lift and slow hole shot but 50 MPH isn't acceptable either.
I've taken all 3 plugs out and all it does is blow water. No matter where it is trimmed to.

I used to have a great hole shot and great top end and good boat control
I should mention with all of my experimenting, the boat wants to slide on top of the water instead of lifting and going on plane.

Thanks for any help you can give.



P

[Almag6]

Do a search online about lightning gear case vs magnum. Lots of threads out there. The magnum is punching a bigger hole in the water making you blow out.
You'll need a new prop, prop work, or both.

[tdt91]

Get a Merc Trophy and a Michigan Wheel #200 hub kit. A 23P may be right.

[Jumping Jimmy]

I had a 200 HO and had to replace a lightning case with magnum. I put solid plugs in my Tempest prop and it helped tremendously with the blowout issue. Give it a try and if you need some venting just drill your plugs until you hit it right

[Jig N Pig]

Thanks for info guys

[Ken-Nuk]

Well i just thought I would post about some of my experience with my old boat. (201 status w/2005 Evinrude etec) One problem I had when I switched to a Evinrude M case lower unit. it would run good with a 4 blade prop with the weed ring installed, but when I switched to a 3 blade prop it was very hard to get out of the hole without the prop blowing out. The cure was installing a 3 blade prop seal That is much like the 4 blade weed guard but must be used for the magnum case because of its slightly larger case size. (3 blade prop seal part#0346462).

[Jig N Pig]

I do have a 4 blade and will try it. Also did have a weed ring on my 3 blade. Thanks Ken Nuk.

[518DMK]

I had the same problem, I installed a prop seal ring that goes on the inside edge of the prop itself, it was a Mercury Part # 878421 PROP SEAL RING
this helped the hole shoot issue but I still don't get the top end that I used to get from my old Ficht 200 motor.