Four cycle engine

April 2, 2013

Four cycle engine from 1905

IMPORTANT NOTE: The K&B 7311 glow plug works perfect in HP VT four stroke engines. Don't use R/C, 4 cycle, miracle, wonder or any other plugs that have anything extending from the end. These plugs can hit and destroy the rotary valve. Early VT 21's use a standard short plug like the K&B 1S 7321. You can identify the early version by the rotating valve, early used a bronze valve in a chromed sleeve, all later engines used a chrome valve in a bronze sleeve.



9.5 oz

Prop Size

8x5; 8x6; 9x5; 10x4

Prop Nut Thread

1/4" x28

Piston/Cyl Type

Dykes Ringed ABC


Hardened supported by two ball bearings

Valve Type

Hard Chrome Rotary in bronze sleeve

Valve Train Drive

Bevel and spur gear via shaft

Carburetor Type

Twin Needle

Glow Plug

K&B 1L 7311 Std Long

See note a bottom of page about glow plugs in VT engines
HP's unique design of four strokes are the quietest made. In fact, the VT 21 rivals an electric. Both engines are equipped with suburb mufflers that easily meet all DB requirements.
HP engines have always been renowned for their unsurpassed quality and precision. This tradition continues as all HP four cycles are produced with the latest computer controlled machines in our Southern California facility.
!HP has always been known as the smooth runners. The one piece hardened steel crankshaft with a massive counter weight is supported by 2 ball bearings. A light alloy forged conrod and cast piston are balanced perfectly. You'll be surprised just how smooth a engine can be.
OVERHEAD BBC rotary valve technology
Bronze, Brass, Chrome. HP pioneered rotary valves in model engines and utilize a true hard chrome valve running in a bronze sleeve. This arrangement never requires adjustment. No valve float and or power robbing valve spring tension to overcome.
Small Engine Diagnostic Method - Four Cycle
Small Engine Diagnostic Method - Four Cycle
Four Cycle Engine Process
Four Cycle Engine Process
4 Cycle Engine - Game over (1/2)
4 Cycle Engine - Game over (1/2)

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