KB Super Duty 120" M-8 Pistons with 'Line2Line' Coating
Boise, Idaho based distributor HardDrive/WPS continues to add to its V-twin product line with several new brands now available ready to ship to U.S. dealers - from National Cycle screens to ODI Lock-On V-twin grips and Flo Motorsports adjustable levers and MX style footpegs to BOSS Audio products and, as seen here, KB Super Duty Series pistons for 2017 and up 114" and 117" M-8 applications.
Designed for 120" displacement and giving an 11:1 compression ratio, they have generous valve pockets to accept 1 mm larger valves and are available for stock cylinders bored to 4.125" and in +0.010" increment bore sizes right up to +0.060 for 4.185" bore.
Based at Carson City, Nevada, manufacturer United Engine & Machine (UEM) is noted for its use of high-quality materials and advanced coatings. These Super Duty Series KB pistons have a hard anodized crown that aids with heat deflection and reducing corrosion from alcohol fuels and top ring groove hard anodizing eliminates micro-welding of the ring to the groove, maintaining a flat and smooth surface for best ring seal.
They have round wire locks and premium Hastings 1.2 mm, 1.2 mm and 3.0 mm rings with a steel nitrile top ring and a ductile Napier second; the complete kits include two pistons, rings, pins and locks.
These M-8 series pistons are made in forged 4032 low expansion alloy and feature 'Line2Line' .003" total thickness abradable skirt coating as standard - a polymer based formulation applied to the thickness of the piston-to-wall clearance for a ZERO install clearance. The coating abrades in on start-up to hone for the perfect fit per cylinder, eliminating piston rock for the best possible ring seal with no piston slap noise and a tight, quiet running clearance.
By reducing the clearance, engine efficiency is improved, lowering friction, maintaining an even oil film and protecting against scuffs and excess wear. Also available for Twin Cam applications, KB standard skirt coated and some 'Line2line' coated Super Duty Series performance pistons are offered in hypereutectic 390 alloy as well as 4032 alloy for some applications.