4 cyl. Outrigger Hydro


Help Support Intlwaters:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Hi Bradley,

great to see the 56 Alpha in a boat, look forward to seeing what it can really do, nice to see a four stroke in a rigger, I've wanted to try it for some time now, but other projects always get in the way, by the way, the novarossi 46 flywheel fits the 56 Alpha perfectly as well,

good luck with the project

Thank you Shane and David,

Shane if you have a rigger collecting dust you should try out your Alpha .56, looking like 3.7" to 4.5" total pitch is needed to get into some speed.

The .56 alpha is a good choice if you want to opt out on water cooling. The full course of oil flow through the cam up the rod tubes to the

rockers and out the exhaust makes it a winner. Valves are efficient hence the torque is there to tap into high pitched props which is a

easy to gain with big dia. props but past 52mm is wasting the power on tap least for a 3ft / 3lb rigger. Will try the props shown in pic

left to right in that order next, hope to test both props next Sat. Need a clear conclusion what prop size makes for a good blend of

thrust and top end speed without stressing out the engine to failure. Thus far the engine is holding up with ease as expected but treading

forward with care to insure I don't ruin it along with watching the trim of the new rigger design as the speeds increase. 25" from the back

of the sponsons to center of the prop hub length gives a reasonable ride thus far.

One thing I have not mentioned is I took vid of a second run on Sat. the file did not save correctly / it will not play. The run had the rigger about

3 clicks leaner with the same prop it was moving faster about 5 mph, the winds kicked in and during a down wind turn it caught air due to rough

water cartwheeled and lucky for me landed back on it's feet. 4 stroke engines have a very narrow peak NV setting once your near the sweet spot

they make a ton of power truly singing it's song. On the straights it did just that going from a hair rich to clearing it throat and moving out with some rpm.

I was alone Sat. had to quickly air up my inflatable kayak and scramble out to fetch, the winds had it about 70yrds out when I got under way. After all

that fuss the heat sent me packing I was toast, content with the testing and thought I had the event saved on my sports cam. The black silicone tube

I use to keep the removable sponsons on had saved the right sponson on impact it shifted the sponson in on the carbon tube without cracking / splitting wood.

Normally there is a retrieval boat with a small outboard to use. I should have had the kayak blown up on tap but thought my fishing pole would be enough.

Still want a rough water rigger so had a custom coupler made for M7x1 threads for Saito .72 four stroke see pic 4.75ft long skinny rigger will later upgrade to

the OS FSa 1.55 Alpha should ride like a Cadillac. 5ft 1.5" total to the end of the rudder.


Last edited by a moderator:
Here is a test hit into the wind using a radar gun, vid with the ABC S-20

prop is stock no mods just balanced and sharpen 3.75" total pitch.

Started with the plug loose to help turn over the engine and forgot to

tighten back, due to fussing with tucking away the starter belt. Did a gps

read using a Dynamite speed logger with the plug tight and gained 2 mph.

Still not enough pitch later ran the Octura 2250 water was getting rough into

the wind passes, couldn't get on the throttle in the turns to build up speed for

the pass but promising. No issues on launch or prop walk, pitch is better for the

4 cycle engine at 4.33" should bust 50 mph next. Put wider carbon booms on today

to combat windy water chop was a battle on Saturday, will try again next weekend.

22" stance should help originally 18"

Confirmed with radar / plug tight does get 44mph with the ABC S-20

Water is a bit rough so mainly on the throttle along the shore line.

Aired out S-20.jpg
No flow measurements Tyler, is this for a boat / what is the game plan?

I did the break in with the engine in the boat - flywheel / drive line / prop mass - AC set at 67F
4 - 4.5 turns out with a low throttle start will be a safe bet given the load.

In the last vid the engine was within 4 clicks of going lean.
The rigger is running with 2.7 turns out / with pressure tap..
-radar at 44 mph / 13.7k rpm loaded pass per audio app.
15.8k in the hand no load right before launch.
Thanks Brad, boredom has set in early this year and I took a JAE 21 sitting on the shelf and shoehorned the 56 Alpha motor into it. I am little worried the flywheel does not have enough inertia so I am on the hunt for the same OS 46VZ steel flywheel. I need to redo the linkages and add the OS inflight needle in place of the standard one.

JAE 21 OS Alpha 56 Pic 3.jpgJAE 21 OS Alpha 56 Pic 4.jpgJAE 21 OS Alpha 56 Pic 5.jpgJAE 21 OS Alpha 56 Pic 6.jpg
Craig, a 180 project is doable,
Part of the fun is paving your way to make it happen.

Tyler, the flywheel I used is aluminum see pic. of parts / data.
Also did not go with the venturi extension. Look forward to
your results / vid if able. I am subscribed to your YouTube.

My rigger has no rear ramp which cost additional top speed.
I wanted to keep it pure 3 point to see how much power the
engine makes without assistance. Can add a pad to compare.
24v used to start the thumper with the plug loose.


  • OS71804020.jpg
    429.5 KB · Views: 0
  • kjj.jpg
    357.2 KB · Views: 0
Saito 180 - 11k will need as an example ABC 3418 / 3.4"x1.8" for 6.12" total pitch.
55 - 60 mph