Engine Raising How-To

[Jekyll]

My Yamaha 70 2 stroke maxes out at 4500RPM driving my 5 metre Stessco aluminium bowrider. It's swinging a 13.25 * 17 prop, so first step to raising the WOT is to move to a 13.5 * 15 prop, which should (hopefully) raise my WOT to around 5000 RPM.

Ideally, I'd like to be running around 5200 at WOT, and a check of my boat showed that the engine is set as low as it can possibly go on the transom.

SO, assuming I'll be getting around 5000 at WOT on the 15p prop, next step might be to raise the engine a hole or two ... at present the cavitation plate is about 1" below the keel.

What's the best method of doing the engine raise? I thought of lowering the jockey wheel as low as it would go, fitting a block of wood below the engine with engine lowered, loosening the required bolts then raising the jockey wheel until the engine aligned with the next set of bolt holes. Too dangerous? Any alternative methods out there for someone without a hoist?

P.S., just in case you're wondering, engine linkages are correct so I'm getting max throttle on the engine when the throttle lever is at full.

[blaze]

you have got it one, little easier with a couple of people
cheers
blaze

[Spaniard_King]

Jekyll

I agree with Blaze....your on the right track.

Just take your time and think about what your doing

Garry

[Chimo]

Jekyll

Agree with the above two replies.
Also may I suggest some more. I did as suggested above but also as below.

When I raised a couple of 115s I also used a hand ratchet cable block and tackle unit from a Auto Barn or similar above each motor as my insurance policy and to be able to fine tune height to get bolts in without drama. I also did it solo.

You might find better result to have cav plate at or just above lowest point of keel and Tiger Shark (TS) or Doel Fin (DF) also can frequently be beneficial fo hole shot and slow plane but with motor (s) trimmed up so at high speed you can often have the TS of DF clear of the water if the motor (s) are high enough. Too high and you will get cavitation esp on turns. Trim will affect this too.
Hope this helps

Chimo

[2iar]

That's exactly the process I followed on my 70hp, as recommended by Garry. I did it myself and it took about 10 minutes.

I was very pleased with the results - it's a much more comfortable ride, faster at each rev level and much easier to trim correctly.

Good luck,
Mike

[Cloud_9]

your cav plat needs to be about 1" above the bottom.
with straight edge.
have a couple people with you to steady the motor while you wind the jocky wwheel.
Cheer Cloud 9

[bin_lookin]

i did mine with a trolley jack &peice of wood laying flat on jack just to protect bottom of leg it was easy to do just remember to choc your wheels both sides cheers bin lookin