Denco H1 Porting Specs

Exhaust

87.5 deg. ATDC, 33.8mm from cylinder top

Transfer

120.5 deg. ATDC, stock

Intake

100 deg. ABDC, remove 2mm from intake side of piston skirt

Exhaust Port Width

Stock, DO NOT widen, raise entire port roof maintaining stock shape as closely as possible.

Ignition Timing

3.46mm BTDC for all year models

Piston Clearance

.0028" with stock pistons

Cut Heads

.025"

Chambers

Denco slienced 01-3 or 01-3C

Main Jet

102.5 to 107.5 (start rich)

Spark Plugs

Points: Champion L2G
CDI: Champion L55G

Optional

Competition clutch springs 03-1
34mm carbs

Max. H.P.

72 at 8500 ROM