Here are photos of some great racing kits for historic two strokes by Jeff Henise.

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Above (Highwayman / RCR TZ125): A very special late model TZ125 top end here. This was created from a TZ250 5KE4 (2003-2009) drum valve cylinder. If you can find one you are lucky! These are very similar technology to Yamaha YZR500 GP cylinders. The drum valve closes not only the main exhaust port but also the side exhaust ports and opens to a resonate chamber at low revs. The result is the potential for both bottom end grunt AND explosive top end horse power. Really this kit pulls from 10-14k RPM. Earlier TZ cylinders with the guillotine valve only valve the main exhaust port for less effect. I have had the privilege of spending many hours with Roland Cushway (Roland Cushway Racing) who taught me everything he knows about setting up these cylinders. We worked closely together to make custom power valve components, a cylinder head insert, and design the porting. Roland had access to special cylinder that was ported by Brian Turfrey (of team Roberts fame) that we studied to derive the porting specs. The machine work and porting was done by myself (Jeff Henise – Highwayman Bikes), with careful inspection and guidance by Roland. In my early days as a machinist I would hear stories about the machinists that could work within tolerances of a thousandth (0.001″) and that when one arrives there that are doing pretty well as a craftsman. Then I would hear stories of the true master craftsmen who could work within tolerances of tenths of a thousandths (0.0001″). If I have ever met one of these 0.0001″ masters, Roland Cushway definitely qualifies, and has taught me a lot about the patience and tenacity required to do so.

Here is a video of me riding the TZ125 with this kit at Laguna Seca in July of 2021, I finished 10th with my best laps being 6 seconds slower than the lead rider, i still have a lot to learn on these little GP bikes as a rider!

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Above (Mojo Yamaha TZ750): Cylinders were ported by Scott Clough, and I made the heads with insert chambers and modified water spigots. Wayne Wright taught me how to convert old parallel twin TZ350 and TZ750 heads to accept inserts with toroidal chambers as shown above and have redirected water flow for more efficient cooling, during construction of my record holding land speed TZ350 The Orange Bird.  This top end kit was for Dave Crussell of Mojo Yamaha Racing, and has run on his TZ750 since the 2018 International Challenge at Philip Island, AU. It has since as of this writing (2021) logged MANY racing miles and is still going strong. I recently made an upgraded water pump impeller to help it cool even better. (photos below)

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Above (TZ350 – Orange Bird): A lot going on here! This is one of two matching top end kits I made for the Orange Bird Project – the fastest ride on 350cc motorcycle ever recorded at Bonneville. These started life as piston port TZ250G cylinder blocks that were bored out to 350cc with added cylinder length to accommodate a 58mm stroke. They were converted to a 3-port exhaust, BIG reed valves, and big intakes with boost ports. This required a LOT of welding including welding in of an intake bridge to support the pistons. The intakes and exhausts are so wide that 1/2″ diameter cylinder studs were required that were cut to their center line to act as part of the port passages. these studs sealed to the cylinder block with O-rings. Nikasil plating was done by Millennium Technologies. The heads were insert style as described for the TZ750 kit above, with toroidal chambers.

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Above (YCS1 Kit 1): A top end and ignition kit for the Yamaha YCS1 CS3 CS5 200cc air cooled piston-port twin. Legal for racing in AHRMA GP200, GP250, and F125. Modifications include: ported exhaust, transfers, and intakes; spigots welded to intake and exhaust to accommodate new port shape and mounting of the carbs and pipes (the pipe spigot has two O-rings); modified pistons with appropriate skirt length and windows to feed the secondary transfers; O-rings for head gaskets, CNC machined combustion chambers with squish band to match piston dome curve, and locating dowels to center the heads onto the barrels; bores are nikasil plated by Millenium Technologies; the ignition is a magneto CDI from HPI with a custom retard curve and rev limiter. This kit is for Scotty Pultorak (Scotty’s Fabrications) a talented fabricator in Chicago, who is building a replica of the Highwayman F37 frame with a YCS1 motor. I expect that it will be quite a potent combination! He expects to race the bike with AHRMA in the 2021 season. Also included were carburetors as described in YCS1 Kit 2 below.

Above (YCS1 Kit 2): Another top end and ignition kit for the Yamaha YCS1 CS3 CS5 200cc air cooled piston-port twin. Legal for racing in AHRMA GP200, GP250, and F125. Modifications include: ported exhaust, transfers, and intakes; spigots welded to intake and exhaust to accommodate new port shape and mounting of the carbs and pipes; modified pistons with appropriate skirt length, and windows to feed the secondary transfers; O-rings for head gaskets, bores are nikasil plated by Millenium Technologies. Carburetors were bored to maximum legal size and fitted with custom spigots for mounting to the cylinders. This kit included the ignition system pictured with YCS1 kit 1 above. The exhaust spigots contain a female flange requested by Gary Braun of Retrodyne who will be making the pipes, and very nice looking pipes does he make! This kit is for John Scales who finished 3rd overall nationally in AHRMA GP250 and CB160. He aspires to go faster and is building a new bike with this kit to compete in AHRMA GP200/GP250 in the 2021 season.

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Above (YCS1 Kit 3): No holds barred here! For the YCS1 racer that wanted it all. Modifications include: replaced iron liners with aluminum nikasil plated liners; added secondary transfer ports and ducts; intake and exhaust spigots to accommodate new port shape; O-ring sealed toroidal combustion chamber heads; programmable HPI ignition (as shown in YCS1 kit 1); crankshaft modified with long rods; crankcase with enlarged transfer wells; stainless steel Highwayman Pipes; and as icing on the cake a full set of ceramic bearings from World Wide Bearings! Photos show one of two identical kits provided to Duston Johnson, who rode his Highwayman Powered “Yamahonda” to a 2nd place overall victory in AHRMA GP200 and GP250 for the 2019 season.

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Above (Highwayman F37 cylinder): This is literally a homemade cylinder. I (jeff Henise) made the foundry patterns, sand cast the blanks in my back yard, did the heat treating, machining and porting. They were nikasil plated by Millenium Technologies and ended up propelling me to a GP250 national championship (AHRMA road race) and a 2nd over all national victory in GP200. Here is the older story of the motor with the original modified Kawasaki F3 cylinders: Highwayman F37.