Puch 1hp restrictions

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The differences between a 1.5hp and a 2hp Puch are listed on the Puch horsepower differences page, but the 1hp models had a few restrictions all to themselves. This page explains and shows those restrictions. Some 1hp models may have slightly different restrictions than what is listed on this page, so if yours has a restriction that isn't listed, take a picture and add it.

Cylinder

The intake port on the 1hp cylinders is severely restricted where the intake attaches and/or inside the bore.

A restricted #5 cylinder

A restricted #5 cylinder

A restricted #4 cylinder

Intake

The intake itself on a 1hp cylinder matches the restrictor and is therefore very small.

1hp restrictions2.jpg

Head Gasket

The 1hp cylinder has an extra-thick head gasket, which reduces compression. Replace it with a skinnier one, or if you have a good seal between head and cylinder, remove this gasket completely.

1hp head gasket on left, regular head gasket on right

1hp restrictions3.jpg

Exhaust

The exhaust port may or may not be restricted. If you want to figure it out, compare this picture to the ones on the Puch cylinders (aluminum series) page.

1hp restrictions6.jpg

However, the exhaust itself MAY be restricted. This pipe came from a Sears Free Spirit, and this restriction is not necessarily found on all 1hp Puchs.

Restricted exhaust.JPG

Other

Other potential restrictions include a longer piston and an airbox restriction.

To check for the piston restriction, rotate the flywheel until the piston reaches TDC. Then unbolt the intake from the cylinder and look through the intake port into the cylinder. If the piston skirt does not completely clear the intake port, this is restricting the cylinder. You can correct this by marking the exposed part of the piston skirt, then griding it off.