Tuning the kyosho wavemaster - Rum Runner Racing

TUNING KYOSHO’S WAVEMASTER

By Andrew Gilchrist & Tom Jones

A little effort can transform a Wavemaster fun tunnel into a scalded cat!

Motor: The Wavemaster’s sealed can 550-powered, bushed, outboard pushes the hull to a top speed of 12 mph. But this outboard easily copes with far more power.

Running bearings, Octura X640 prop, 7 cells and Kyosho’s 550 modified had the stock wires and plugs at meltdown. Deans 12 gauge and Ultra plugs relit the fire.

Fitting a Hughey single gearbox required only one extra hole in the motor mount to mate with the Hughey’s output plate. Four 5/16" spacers under the mount enabled an Octura flexhex to the fitted to the output and flex shafts.

Hughey D3.5 and gearbox fit easily to Dolphin Outboard. A test pin makes an on/off switch.

The long can was replaced with a Hughey D3.5 11 triple (serrated hard brushes, red/11oz springs). Kyosho’s steel cooling coil cools and acts as a torque ring. A 1.91:1 ratio gives 3.5-minute runtimes (1.5-2mins is a lot less wear and tear). A 17-19-turn arm up to 12 minutes!

To provide a stable and efficient ride angle the stubshaft runs ¼" shallower than the sponson (at the centreline of the drive dog) and 1-2 degrees negative angle (rear higher than front).

Seven cells piggyback into the rear of the battery box to place the CoG 6.5" from the transom (27% of hull length).

Speed control: With 6 times the standard torque a micro switch acts like a detonator. Unless you throw start, wheel stands and flips are unavoidable. A Hughey speed control was mounted between the radio and battery boxes. Power cable runs around not through the radio box eliminating one source of leaks.

Power from Hilltop NiMH cells runs through a Hughey 4 speed. AAA NiMH’s connect to the receiver and servos using instrument test pins

The steps in the control were tailored to the hull/prop using fuse wire to pinch coils and alter resistance. Reliable wet or dry the control gives smooth starts fast cornering and ballistic top end, and wheelies on demand!

Steering: The high speeds now reached place high torque loadings on the leg, testing the standard servo. The fix? A 100oz servo.

Waterproofing: The leaky radio box means expensive electrics are prone to water damage. I made a braced balsa box with rubber boots for the steering (2) and speedo (1) pushrods and a pinhole for the aerial and on/off switch wires.

The servo mount was replaced by 3/8" birch section CA’d across the radio box. Five AAA 550mah NiMHs are half the weight of four AA Nicads.

Power wires from the AAA’s were connected using color coded test pin/sockets. Power leads were soldered on to the receiver pins. A plug/pin at the transom makes a water immune on/off switch. Plastic card separates batteries from receiver and a shelf holds the receiver above any water leakage.

The box was silconed in place. A trimmed lunchbox lid made a sealable surround and a shirt box the lid. An aluminum tube epoxied to the box holds the aerial

The Hull – Beef it up! A sharper, straighter stiffer hull significantly improves efficiency and handling to make the most of the extra power.

Sharper edges assist handling. Spray rails and strakes create lift and reduce drag. A small L-shaped extrusion sharpens the inside sponson edges. A 1/4" L-shaped extrusion makes an inverted spray rail along the outside of the sponsons. A strip of balsa wedge stiffens and narrows the ride surface to 1 1/8".

The trailing edges of the tunnel and the sponsons were sharpened so water breaks off rather than flowing toward the electrics and causing drag.

Straighter: Find a flat surface and weight the hull so the planing surfaces are at equal angles and the vertical freeboard ‘square’ to the central hull. Hold the hulls in line by CAing bracing across the transom and sponsons bottoms.

Hull was trued, the transom was stiffened with epoxy fillets and the motor mount with ply. ABS moldings sharpened sponsons edges and made spray rails

Stiffer: In the Wavemaster flex in it’s center hull twists drivelines and sponsons reducing efficiency (speed) and making handling less predictable.

Cut Quarter sized holes in the sides, bottom and front walls of the battery box nearest the bow. Between the bottom of the battery box and hull is a sheet of foam. Running epoxy between these surfaces produces a stiff light sandwich.

To stiffen the ABS motor mount, three layers of 1/6" ply were cut to shape and laminated on using epoxy. The original mount points were drilled for ¼" screws. The motor pivot was bored from 4 to 6 mm and a new pin turned to eliminate slop.

Across the transom the vertical surfaces above and below the hull and deck seam were roughened and filled with a gusset of epoxy.

Internal braces were used to stiffen the front of the hull. ½" ABS L-sections were inserted through the holes and placed across the hull bottom to the edges of the sponsons. A generous dollop of epoxy held them in place. The hull was inverted and the same done across the inside of the deck and sponson.

Pretty: And the 4-color paint job was done using Tamiya TS spray packs.

Lessons. Get the basics right, no cheap alternatives, don’t reinvent the wheel.

Hotups create loads some OE parts can’t take. Set up a reliable platform before using more power. Waterproofing, wiring/plugs, ballraces/props/flexhexs may seem mundane but they’re trick and fast. If it don’t run, it ain’t no fun.

Items I thought costly proved durable and capable. Their fun per dollar ratio improves each run. The cheap gear is in the trash. Would you tear up a $50 note?

Avoid reinventing the wheel. Everyone I asked for help gave it. That includes Dick Crowe, Ray Fuller, Steve Hill, Ed Hughey, Ian Pearson, Neil Reesor, Greg Schweers, Allan Shilitto, Jay Turner, Doug Twaits (Jr and Sr), Jeff Vasquez, Ian Williams and the Wollards. Why fool around when a legend can help?

What we used:

Hull: Wavemaster F1 Tunnel Hull & Dolphin II Outboard $99

Motor D3.5 11/3 $45

Cooling Coil: Kyosho $17

Gearbox: Hughey Single 1.91:1 $52

Coupler: Octura Hex Flex $12

Propeller: Octura 640 $10

Speedo: Hughey 4 speed $52

Wiring/Plugs: Deans 12AWG and Red Plugs $11

Servo: 100oz $40

Paint: Tamiya HS series (4 cans) $18

ABS Extrusions and 3/8" sq. birch: $10

Like a scalded cat - out of the hole and away!

Call 911 this thing’s on Fire! These modifications take a weekend and transform the boat from a fun runner into a flying, skating ball of fire. The motor/gearbox combo is deadly. This hull and ‘soft’ gearing run high, dry and 30+ mph

Special thanks to Andrew Gilchrist & Tom Jones for this great article. For additonal information contact Andrew at andrewg@maitland.nsw.gov.au

This Article was written by Andrew Gilchrist Exclusively for Rum Runner Racing. Use of this article is prohibited without written permission from Rum Runner Racing.