Some (Re)Assembly Required

It’s an Old Fashioned Hot Rod Rebuild for Our Project Copperhead Kawasaki 250X

Text and Photography by Kevin Shaw

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“No, I was not jumping surf,” I growl, defending myself to my senior editor. “I was at Lake Elsinore with my wife. All I did was take a corner and it swallowed a gallon of water.”

Once just a loaned test mule for shootouts and ride-a-longs, our ’07 fire engine-red Kawasaki Ultra 250X was clinically dead, having ingested a mouthful of water via an aftermarket cold air intake system that fixed the breather outside of the engine compartment. In preparation for last year’s Long Beach-to-Catalina-and-Back race, Personal Watercraft Illustrated was lucky enough to procure quite a bit of support from both Kawasaki and the aftermarket who all happily supplied us with the boat in question as well as a variety of performance goodies, including the kit in question.

The cold air kit looked promising. Like a ram-air induction system on a classic musclecar, the aftermarket breather would employ a long, plastic-mold-injected tube that ran from the supercharger’s inlet to outside the hull, beneath the glove box, capped with a large K&N filter and nylon sock; and it did its job. The Kawi ran phenomenal during the Catalina race and on several rides afterwards. But it would be the downfall of our 250X’s stock engine that fateful Saturday afternoon while gallivanting around a placid lake; just one tight turn drowned the red Ultra.

Like the pump of any watercraft, a supercharged intake creates a substantial quantity of vacuum. Although buffered by an insulated plastic box, the intake’s draw sucked the oncoming water through its cotton/paper mesh air filter and into the supercharger. Thankfully not at throttle, the pressure of the condensed water was pressed into the intake manifold, filling the cylinders. Since water’s density disallows it from compressing like air, the mass within the cylinders refused to let the valves open or the pistons to rotate, shutting down the reciprocating assembly, or hydro-locking the engine.

Potential damage to an engine in such a circumstance can be as catastrophic as smoked bearings, bent connecting rods, cracked or shattered pistons, splintered valves, permanent damage to the cylinders, cylinder head, or as bad as punching a hole through the side of the cylinder wall, all in the effort to displace the massive degree of pressure within the cylinder. Crossing my fingers such was not the case for our Kawasaki; I rushed the ski over to Greg Beaver at Circuit Jet Sports for the prognosis.

Thankfully, after extracting the engine, our damage assessment wasn’t as grave. While heavily corroded and pitted, the cylinders appeared to be in good shape. The pistons, rings, valves, lifters, shims, valve springs, and retainers would all need to be replaced. Additionally, the cylinder head would require some machining to allow the new valves to seat properly and the cylinders to be freshened with a light honing. On top of our rebuild, we would port match the intake and exhaust ports on the head and the intake and exhaust manifolds according to their respective gaskets and polish the supercharger.

Glenn Dickenson and Bill Chapin from R&D Performance would prove themselves as true watercraft performance experts, providing us with a king’s ransom in aftermarket equipment to not only provide some added speed but ensure our 250X engine’s longevity. R&D, on the surface, might appear to some as being behind the 8 ball when it comes to maxing one’s speed, but the devil is in the details. Like my cold air intake, the kit was ultimately dangerous. R&D prides itself of providing the best and most heavily tested equipment to not only improve watercraft performance but to guarantee that the engine is running at its greatest potential when maintained properly.

Using a specially designed gauge, Greg performs a compression check to verify the condition of the reciprocating assembly. By “bumping” the motor (mildly rotating the crank, rods, and pistons), the compression check can decipher the degree of damage done to the engine’s vital components such as the crank, pistons, and connecting rods.

Fully disassembled, we were able to fully examine the wear on each of the engine’s components. Much to our relief, the crank, bearings, and connecting rods were in pristine shape, saving us from having to rebuild the bottom end.

The brunt of damage was found in the top end. Corrosion was widespread on the valve surfaces and the cylinder head itself. Amazingly, none of the valves were snapped, bent, or splintered, evidencing that none of the valve guides would need replacing as only a small quantity of water actually entered the engine itself.

Sandblasted and repainted with heat-resistant semi-gloss black engine paint, the exhaust manifold’s ports were scribed to match the gaskets and opened up using a sand scroll. Port matching allows a greater quantity of flow, which when done properly, provides drastic performance gains. Additionally, extrude honing smoothes the ports’ surfaces removing the porosity left by the casting process.

Employing the same methods – only more carefully around the valve guides and avoiding the valve seats – cylinder head porting can be rather easy and extremely beneficial to top end performance. Showing two ports (one exhaust and one intake) in stock condition illustrates how porous and confining the factory ports are. Freeing intake and exhaust flow allows for greater ingestion and evacuation of clean, primed air and spent gases.

Reprairing the valve seat is a long, but rather uncomplicated task. After installing the placement rod through the valve guide, the brass-colored valve cutter tool needs to be fitted with specifically measured cutters (intake: 45, 32, and 55-degrees, exhaust: 45, 32, 60-degrees). To note your progress, first coat the valve seat in machinist’s dye.

Valve seats feature three distinct angles that “bloom” from inside the port outward. (Befittingly, the head of the valve is appropriately named the “tulip.”) These cutters, when firmly turned by hand, will resurface each angle individually.

To ensure a complete, gapless seating of the valve, each valve needs to be “lapped.” Lapping requires the face of the valve to be coated in first, a coarse grinding compound and spun against the seat and repeated with a smoother compound until the process produces a smooth, matched surface.

Using a suction-cupped lapping tool, simply insert the coated valve into the guide and spin manually, repeating the process until the mating surfaces are matched. To verify, use a flashlight to see if any light seeps through.

With our cylinder head finished, we can ring and gap our pistons. Before installation to the piston, measure the gap between the ring ends with the rings close to the bottom of the cylinder where the cylinder wears lowest. Each piston requires five rings, a top ring, a second ring, two steel oil ring rails, and an oil ring expander.

Installing the piston to the connecting rod requires a new piston pin and snap ring. Reusing old snap rings could spell disaster as snap rings notoriously warp during removal. With the rings, pins, and piston journals oiled, we’re ready for the cylinder.

Using a rather rudimentary honing tool and some machine oil, Greg lightly scours cylinders. While scored lightly by corrosion, the cylinders retained their tempered coating which helps protect the aluminum cylinder block from overheating, warping, or cracking.

The R&D’s crankcase ventilation system was designed to relieve excess crankcase pressure in the oil breather case. The kit includes this billet spacer to double the volume of the OEM crankcase breather. Additionally, a piggyback vapor/oil reservoir plumbs directly to the factory oil separator tank. This kit is aimed at ending oil blow by, relieve excess crankcase pressure, and trap excess fuel vapors.

To alieviate some of the Kawasaki’s nose plowing, R&D developed this 1-degree wedge spacer. Installing between the nozzle and the pump, the wedge helps to angle the nozzle slightly upward, raising the bow to plane faster.

Thanks to the skills of California Polishing in Huntington Beach, CA, our once bland supercharger came back looking like something worthy of the Pebble Beach Concourse d’Elegance. A little acetone or thinner through the internals helps to clear the housing of any debris that might have snuck in during the polishing process.

R&D provided us two imperative items for our build: first, a billet wheel hub kit which offers precision serpentine belt alignment. Made from CNC-machined 6061 billet aluminum, the hub is significantly stronger than stock. Second was the brand’s supercharger pulley. ¾ lbs lighter than the stock steel pulley, it’s capable of delivering anywhere from 2½ to 3½ lbs of added boost and 30 extra horsepower.

Replacing the guilty cold air intake system, we obeyed Bill Chapin’s admonition and installed the factory air box, which upon closer inspection offers less flow restriction than the replacement aftermarket kit! R&D sent us their engine compartment breather which allows cool outside air into the engine compartment without jeopardizing the engine.

Many will remember that PWI was the first to install TBM’s adjustable steering neck last year. Now, Project Copperhead will be one of the firsts to employ its steering knuckle. The system is meant to reduce the steering ratio while improve response and tactility.

Concerning high performance powerplants, nothing speaks louder to me than the 426 Hemis of the mid 60’s to early 70’s. Sure, it’s a little odd for a watercraft, but why not? A heavy coat of Chrysler Race Hemi Orange engine paint and several coats of textured heat-resistant wrinkle black paint for the valve cover definitely distinguishes this 250X from the crowd.

Although not completely finished, our Hemi Orange 250X 1.5-liter muscle motor is looking quite daunting. New, larger fuel injectors, belt tensioner, serpentine belt, breather system, and a refurbished intercooler could spell some serious competition in the endurance field.

SOURCES:

California Polishing

Huntington Beach, CA

714/847-2166

californiapolishing.com

Circuit Jet Sports, Inc.

Huntington Beach, CA

714/375-7744

circuitjetsports.com

Kawasaki Motors Corp.

Irvine, CA

kawasaki.com

R&D Performance Products

Santa Fe Springs, CA

562/906-1190

rd-performance.com

TBM Racing

Concord, CA

925/321-0427