KB Performance Pistons

KB is offering performance which is not just limited to the road. Right out of the box, KB supplies diamond machined pistons that feature a light weight design and are held to plus or minus one gram within the set. In addition, KB holds skirt sizes of less than one half thousandths (.0005") tolerance from piston to piston.

KB pistons are made of high-strength, T6 heat-treated, 390 hypereutectic aluminum alloy. This alloy yields better thermal efficiency with less expansion and superior wear characteristics. The KB design, combined with the hypereutectic alloy, can be run with less than .001" piston-to-wall clearance with no scoring; the tightest clearances in the industry. In addition, the thermal efficiency of the 390 alloy allows engine timing to be reduced, and the tight clearances virtually eliminates piston noise. All of these features combine to give you an engine that runs quiet, efficient, and longer than previously possible.

KB Performance Pistons affords you the opportunity to build your bike from mild to wild at the most reasonable price around.

HOW MANY CUBES YOU GOT?
Cubic inches are influenced by two factors: the bore, which is the width or diameter of the cylinder, and the stroke, the length of piston travel in the cylinder.

This chart is to help you with computing your engine bore and stroke to find your final cubic inches. It measures the swept volume, which is the displacement between the piston at bottom dead center (BDC) and the top dead center (TDC).

To convert the cubic inches to cc's, multiply the cubic inches by 16.387. Example: 81.6 cubic inches x 16.386 = 1337cc's.

STROKE
BORE		3.50"	3.968"	4.250"	4.500"	4.750"	5.00"
	3.438"	64.8	73.7	78.7	83.4	88	92.8
	3.500"	67.2	76.3	81.6	86.6	91.4	96.1
	3.625"	72.1	81.7	87.4	92.9	99	103.2
	3.687"	74.6	84.7	90.7	96.1	101.5	106.8
	3.812"	79.9	90.6	97	102.8	108.5	114.2
	3.875"	82.3	93.4	100.1	106	111.9	117.8
	4.00"	87.9	99.7	106.8	113	119.3	125.6
	4.125"	93.4	106	113.5	120.5	126.9	133.6
	4.250"	99.2	112.6	120.5	127.6	134.7	141.8

SPECIAL CLEARANCE REQUIREMENTS OF KB PERFORMANCE PISTONS
Suggested Piston-To-Wall Clearance

KB pistons can be installed tighter than other performance pistons. A close-fitting piston rocks less, supports the ring better, and seals the engine for maximum power. When a loose fit engine is desired, the rigid skirt design of the KB piston allows the builder a choice without fear of piston damage. The chart below shows minimum and realistic maximum loose fit clearance for KB pistons.

SPECIAL NOTICE ON TOP RING END GAP
The KB pistons' unique thermal conductivity, ring location, and varied end use requires special attention be paid to top ring gap. KB pistons make more horsepower by reflecting heat energy back into the combustion process and, as a result, the top ring runs hotter and requires additional end clearance. Increasing ring end gap does not affect performance or oil control because normal end gaps are realized at operating temperatures. Failure to provide sufficient top ring end gap will cause a portion of the top ring land to break as the ring ends butt and lock tight in the cylinder. The broken piece may cause further piston or engine damage. Safe top ring end gaps can be found by multiplying the bore diameter by the appropriate ring end gap factor from the adjoining chart. Example: 3.5" bore "Street Normally Aspirated" = 3.5" x .0065 = .023" top ring end gap. NOTE: Second ring end gaps do not need extra clearance. As a general rule, retarding spark timing 2 to 4 degrees makes the best horsepower when KB pistons are used. Excessive spark advance, lean fuel mixture, or too much compression for the fuel and cam used will make heat sufficient to butt piston rings with as much as .060" ring end gap. Nitrous engines need a spark retard.

RING END GAP FACTOR AND CLEARANCE CHART

APPLICATION RING END GAP FACTOR PISTON-TO-WALL CLEARANCE

STREET NORMALLY ASPIRATED .0065" .00075" - .0015"

STREET NITROUS OR SUPERCHARGED .0080" .0015" - .0025"

FLAT TRACK GASOLINE .0080" .0010" - .0030"

FLAT TRACK ALCOHOL .0060" .0010" - .0030"

DRAG GASOLINE .0075" .0010" - .0030"

DRAG ALCOHOL .0065" .0010" - .0030"

DRAG SUPERCHARGED OR NITROUS GAS .0095" .0015" - .0030"

DRAG SUPERCHARGED ALCOHOL .0085" .0010" - .0030"

DRAG SUPERCHARGED FUEL .0115" .0020" - .0040"

HASTINGS' RINGS

KB Performance Pistons is supplying all* of its motorcycle pistons with Hastings' piston ring sets.

Hastings' is recognized the world over for exceptional quality and performance. A recipient of multiple industry awards, Hastings' was honored by Harley-Davidson Motor Company for above-board service and quality.

Hastings' rings offer superior oil control and less friction, which translates into more horsepower and less wear on your cylinder walls. Their Flex-Vent system offers easy installation.

Hastings' cutting-edge technology and commitment to quality made us believers. When these rings are combined with KB Performance Pistons, you can be assured of top performance. Before installation, be sure to read the brochure included with your set of pistons to properly gap the Hastings' rings.

RING OVERSIZE INFORMATION
All* KB motorcycle pistons are sold with rings. Special note: KB263 oversizes .060", .070" and .080" are supplied with ring set oversizes that do not match the piston oversize. The KB263+.060" is supplied with 2M6127-STD rings, KB263+.070" is supplied with 2M6127+.010" rings, and KB263+.080" is supplied with 2M6127+.020 rings.

KB299 and KB300 are NOT supplied with rings. Hastings' does not make a ring for this application. Please call your local dealer for a manufacturer that does.

(916) 638-9008 • Fax (916) 638-0510

Monday-Friday 9am-6pm Pacific

3322 Luyung Drive • Rancho Cordova, CA 95742