Design: Boat Chaser/Ocean Surf HULL with a RELIABLE ENGINE

[E350]

We ride the Sacramento River about 12-20 hours a week. So what are your design recommendations (for me at 205 lbs.) for a boat chaser/surf HULL with a RELIABLE ENGINE?

My guess that engine displacement would be in the 850 to 950 cc range (which is only a guess based on my limited experience with the single carb Yamaha SN SJ 701cc). (Flat water flipping is NOT intended and not required.) A 50 hour engine rebuild requirement is simply not an acceptable power/reliability trade off to me.

I would actually like the hull design and boat balance to be focused on ocean surf riding (Pismo?, etc.). But because I am somewhat familiar with the impact zone from windsurfing I would not try ocean surf unless and until my skills with such ski improve to risk body and equipment.

 

[wsuwrhr]

If you want 1000s of hours out of it with little maintenance. Like I said in another thread, stick with stock. You are out of your realm sir. My apologies.

 

[Big Kahuna]

Honestly, I went from 1999 until 2017 before I ever went to an AM Cylinder. From 99-2003 Stock Porting, 2003-2008 I ran ported 61x, 2008-2012 I ran a 61x Big Bore, 2012-2017 I went back to my 61x Ported Setup..... 2017 I picked up a DASA 6mil Non PV. So, at no time have I really felt I needed that much more power. If you are chasing boats and riding in the surf. A well built ported 61x or Big Bore is all you really need and it is reliable.

 

[Jr.]

Dont go bigger than your traditional Big Bore 760-770 on a 61x cyl
I have had these running surf, by the best of them, running for years!
Charging ignition, B pipe , duel 44’s @ 180 lbs cranking comp.
Good oil and fuel, will run a good long time

Ski ya, Paul

 

[KMN]

Rickter Edge, 701, 155 pump.

 

[E350]

Many, many thanks! There are some threads here on the X about the difference between the 61x, 62t and 64u cases and various mixing and matching of cylinders on them, so a little more direction would be appreciated.

BK and Jr. what is a traditional "Big Bore 760-770?"

I am (generally) not stupid, I just don't have the knowledge at this stage.

KMN thanks for the hull and engine recommendation.

wsuwrhr apologies not required. I know I am out of my realm. And I probably cannot afford the keys to that kingdom...

 

[Yami-Rider]

A big bore resleeved 701, like a jetmanaic 781.

Do you ride every day? 20 hours is hard to put on a ski in a week.

 

[E350]

Summer only and not every day. But both Saturday and Sunday 4-5 hours each day and once or twice midweek for 2 hours each. So you are right, without a three day weekend 20 hours is an overstatement. But 12 is normal. We have the worst house in our little town, but on the other side of the levee, the river is our back yard.

 

[Big Kahuna]

61X has typically has better port timing for more bottom to mid power. 62T cylinders are from Runabouts, great for top end power. 64U is 760 (84mm OEM Size). Taking a 61x and removing sleeves and installing BB Sleeves will give you a 754cc setup. Fair amount of machine work.

 

[DAG]

Rickter Edge, 701, 155 pump.

this is actually decent advice. Light weight hull = several 100cc of "feel power".


You might think you want a 850-950cc motor. But a 701 in a light hull will feel way stronger than a 950 in a superjet. You're just not asking the right question

 

[E350]

You're just not asking the right question

DAG: I have no doubt this is true! I am somewhat knowledgeable and experienced in some other sports and I have been asked questions similar to what I am asking now. My response is generally to redirect the questioner to the thing that they are missing, and then say "demo, demo, demo."

There are some people North of us who super experienced and who have offered to help. We missed a season using our free time taking care of my wife's Mom (which we were honored to do) so I am just now catching back up on my skills. Quinc suggested that we go to Pismo. All of these offers are appreciated. I just don't think I am ready to be around those guys yet. Next season.

 

[E350]

Yami-rider: So is a Big Bore a resleeved 61x engine?

Or is a "Big Bore" a stock 760 engine?

BK our '94 SN SJ has the 61x case with a single carb and it seems to have great low rpm torque.

Will the stock 760 (either resleeved or stock cylinders) have that same low rpm torque?

 

[Big Kahuna]

Yami-rider: So is a Big Bore a resleeved 61x engine?

Or is a "Big Bore" a stock 760 engine?

BK our '94 SN SJ has the 61x case with a single carb and it seems to have great low rpm torque.

Will the stock 760 (either resleeved or stock cylinders) have that same low rpm torque?

Nope. The 760 is a good motor, but port timing not the greatest. There have been many that have been able to make that cylinder work and work well. But it is all about the setup and package.

My Advice Get a 61x ported and bored to 82mm or 83mm (Ported 61x really comes alive at 83mm).

 

[Quinc]

Go to Windmill cove, Miller or CFW on a busy weekend and see if you can test ride some skis. (six packs of beer will help with this) try out a few skis and see what you like. But like everyone else says it sounds like porting your current 701, upping compression to 180, lightened flywheel, bpipe and some carb tuning will be more then enough and a day/night difference from stock. Might even try doing the above adding a 9/15 hooker impeller to your pump, some sponsons, adjusting the pole (I cut 8" off mine) and sticking with the SJ for another season.

 

[McDog]

Big bore is resleeved 61x 701 cylinder.

 

[Yami-Rider]

Jetmanaic is a dual carb 701 engine, 61x cylinder, 62t cases.

 

[Balduccimoto]

I had a 750SX, to a limited Superjet, to 2 different big bore 61x/62t motors, to a carbon ROK, and then right back to a limited Superjet. I went back to the Superjet and I have no complaints. If you want reliable there is nothing like OEM quality with a few dependable bolt ons. Here is all you need:

Superjet, stock motor, b-pipe, head, and prop. Tubbies, footholds, shortened pole, hood straps, scoop intake grate and quick steer.

When you're ready then you can upgrade to a name brand hull. Rickter and Tigercraft seem to be the "go-to" hulls right now.
This is years of experience and blown motors. I wouldn't go back to big bore crap for the surf.

 

[E350]

Balduccimoto: THANK YOU! What year Superjet do you prefer?

The '96 or newer 701 engine with the dual carbs?

The '08 or newer hull design?

Maybe it is just me, but I don't care for our '94 SN SJ bottom hull. I prefer the bottom hull on our X2 the most. But wish it was not fixed steer. I prefer even riding the 550sx hull over our SN SJ hull. But for the surf I would think that a wider hull than the 550sx would be preferred that Is why the Rickter Edge hull is intriguing to me. But I may start with a SJ engine in the X2. I hit the rev limiter on our 650 in the X2 now.

 

[Balduccimoto]

I had a 96 hull and a 08 hull .. I would go for either hull because at the end of the day its going to get tubbies and they will handle very similarly. Find one that is the best deal and go with it. The '94 SN SJ bottom deck is same as 96+ and tubbies make such a huge difference. On Sunday I had the chance to try my modded Superjet vs a stock superjet back to back and the difference is unbelievable .. That I don't know how I rode a stock ski before.

Also editing my previous post to add scoop intake grate .. very important mod.

 

[G-Body]

Go with a lightweight aftermarket hull. I went from a SN to a superfreak badass and the difference was amazing. 61x 701 from a couch, wet jet 46mm carb and intake, fiber reeds, coffman sizzler pipe and a 9/15 hooker. It tops out at 49mph, has a stock gas tank so I can ride for hours and does everything a superjet will do but better.