Please check your engine carefully.

Dykes and conventional rings... A dykes type ring is "L" shaped and is located at the very top edge of the piston. A conventional ring is flat or square shaped and is located about 1/16" below the top edge of the piston.

We do not have Perry carburetor parts for HB engines... Early HB engines were supplied with Perry carburetors (HB made many of the carbs for Perry years ago). Please check your carburetor carefully! HB carburetors have the HB logo molded on the main body. We do have Perry parts for the Conquest and McCoy series 21.

Two different mufflers were used on the HB 20-21-25 engines. Please measure your screw or approximate the length and include it with your order. Only the late style complete muffler is available.

All HB .20 engines were a Lapped Piston Cylinder Design, Both .21 and .25 used a Dykes Ring.

Early and Late HB .40 and .50 models... Different crankshafts, front housings, rear bearings and crankcases were used. You can tell the difference by measuring the rear bearing diameters. The early version uses a 12mm - .472" I.D. bearing and the later uses a 15mm - .590" ID bearing.

On PDP models, in most cases, if the "PDP" letters on the mounting lug are in red it's an early version, if black it's a late version. Only the 40's were made in PDP version, .50's were never PDP. The part numbers we list in the grid are for the later style large crankshaft. We do have front housings, bearings and crankcases for the early versions in the parts price list. Specify size and part numbers when ordering. If not specified, we will send you the later versions.

Most .40's and all .50's used Dykes Type Rings
The Blitz .40 used a conventional ring

Target Drone .61's... HB supplied the U.S. military thousands of .61 for RCMAT's (Radio Controlled Military Aerial Target). Some of these engines have made their way into the consumers hands. They were not fitted with a front bearing and used a prop drive/spacer in its place. These can be fitted with a front bearing and new prop driver. You probably don't have one of these, but to check look behind the prop driver and see if there's a ball bearing.

HB Grand Prix .21 Engines... We were unable to purchase the tooling for the last Grand Prix model HB engines. This engine had square cooling fins and "Grand Prix" on the mounting lug. Parts are limited to stock on hand and supply is very limited on some items.