WHEN THE FIRST KAWASAKI MEAN STREAKrolled off the assembly line, it set a new standardfor the fledgling power cruiser market with itscomfy ergonomics, excellent brakes, and greathandling. However, it just isn’t that mean in theengine department. So, we RoadBike staffersdecided to change that — if only to wipe thesmirks off the faces of Warrior and VTX riders.

A little homework led us to Thunder Mfg.’sThunderstorm High Performance Kit, availableto fit a number of metric cruisers. You send thenecessary motor parts to the factory, and theysend back ported heads, bored cylinders (from1470cc to 1550), 10:1 compression pistons,rings, wrist pins, circlips, and modified gas-kets. The kit also comes with precision-groundcams (available through an exchange program)with slotted cam chain sprockets to allow fortiming adjustments. The new cams providegreater valve lift with a longer duration to balance the enlarged intake and exhaust ports.

The valves are reseated and lapped atThunder’s facility. We also chose the optionalservice of having Thunder smooth and reshapethe throttle bores for better flow to complementthe porting of the heads. This cleaning andmatching helps eliminate inefficient turbulencein the intake tract.

According to the company, with the perform-ance kit and a new pipe, you can expect powerfigures around 100 hp and 100 ft-lbs. of torque,compared with roughly 67 hp and 82 ft-lbs. forthe stock motor.

While you can have the techs at Thunder takecare of the install, we chose to do it at a localshop. Our project bike came compliments of ourfriend and fellow horsepower junkie RichAlexander Jr. at Hudson Valley Motorcycles inMillwood, New York. Rich offered up an ’02Mean Streak 1500 and a skilled pair of hands forthe project. Here, we start our build with theengine removed from the bike and ready toreceive its new parts.

www.RoadBikeMag.com72 RoadBike July 2005

MEANThe kit includes ported heads, a modified throttle body,bored cylinders, modified gaskets, hotter cams, and newpistons with rings, wrist pins, and circlips.

HUDSON VALLEYMOTORCYCLES86 Millwood Rd., Dept. RBMillwood, NY 10546914/762-2722

THUNDERSTORM HIGHPERFORMANCE KITPart #T410 $999Thunder Mfg.21408 N. 11th Ave., Dept. RBPhoenix, AZ 85027623/869-7154www.thundermfg.com

SOURCESSOURCES

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The stock pistons have a concave surface on top (hardto see here because of the carbon buildup). Note thatthe new pistons have a flat top and pockets machinedfor valve clearance.

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Here’s the disassembled engine, with all the old gasketsand gasket sealers removed.

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MEA

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Putting The

In Mean Streak

BY BOB FEATHERPART 1: MOTOR WORK

73 RoadBike July 2005 www.RoadBikeMag.com

First, Rich checked the ring end gap by puttingeach ring in a cylinder and measuring the gapwith a feeler gauge, going by the specs in thekit instructions. (If the numbers don’t match,the rings need to be ground.) Then, beforeinstalling the pistons, he put a clean raginside each cylinder bore, to prevent smallparts from falling into the motor.

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Next up were the cam chain guides (marked“front” and “rear”), head gasket, and locatingdowels.

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Rich then slid the heads onto the motor.

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Starting with the front cylinder, he slid thecompression release mechanism onto the end ofthe front cam. (You need to install the cam inthe front cylinder first, for proper timing.) Hethen lubed the cam lobes and bearing surfacesand set the cam in place, rotating it until thesprocket alignment marks were level with thevalve cover mounting surface (arrows).

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Next, he preassembled the cam chain tensionerper the Kawasaki Service Manual, and installedit in the front cylinder.

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Rich then put the front rocker box on top of thehead. He lubed all the bearing surfaces andapplied Kawasaki Bond Silicone Sealant to thevalve cover mating surfaces on the rocker box,then torqued the bolts to OEM spec.

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He put the brass lifter oil filters back in therocker box and filled the oil reservoirs. Then heinstalled a new valve cover gasket and torquedall the bolts to spec. Moving on to the rearcylinder, he repeated steps 9 through 12 tocomplete the valvetrain assembly.

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Finally, Rich bolted the throttle body to theintake manifold…

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…and called it a day. Next time, we’ll add anaftermarket exhaust and a Power Commander,and finish with a trip to the dyno. RB

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Rich put the rings on each piston, staggeringthe end gaps according to the instructions. Hesnapped in a circlip, put assembly lube on thewrist pin and pushed it through the piston andconnecting rod, and then snapped the secondcirclip in place. The pistons are orientedaccording to the size of the valve pockets — thesmaller pockets (for the exhaust valves) faceforward in the front cylinder and rearward in therear one.

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Rich installed the new base gaskets andcleaned and lubed the cylinder bore. Next, usinga hose clamp, he installed the rings on thepiston and slid the cylinder over the piston.

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