The 34mm bore 4-bolt cylinder.
Race Porting offered, HT, (a EFRA favorite).
Championship Porting offered, HT or HR (a EFRA favorite).
1mm stroked crank fits right in stock engine with no changes.
2mm stroked kit available with the head modifications, (a 27.2cc).
Reed Case poring offered, single boost port.
HP; 5.50 to 6.35
(Champ ported HT, 2mm stroked, 27.2cc top end kits. One with 2mm crank and one sold without a crank, 6.0 HP)
(2mm stroked, not ported, 27.2cc top end kits. One with a 2mm crank and one sold with out a crank, 4.5 HP)
(Champ ported HT, uses stock stroke or 1mm stroke cranks, but prefer the 1mm crank, 6.0 HP)