# Inlet Port Timing : Increasing the inlet timing allows the engine to pull more fuel and air in, in turn creating more crankcase pressure. This is a critical factor in gaining bottom end horse power.

   # Transfer Ports : Now we have the inlet port working well, we go to work on the transfer system. Basically we re-shape the transfer ports to give the fuel and air the best chance of getting to the combustion chamber as fast and efficiently as possible. 

   # Compression : Raising the compression plays an important part in gaining the necessary horse power to give you that winning edge. We do this by machining the base of the barrel down, making the combustion chamber smaller and reducing the squish band. 

   # Exhaust Port Timing : Exhaust timing is something that can really dictate the way your engine performs; increasing it changes the position of the power curve through the rev range, therefore increasing it the right amount is where the answer lies.

   # Piston Weight :  We machine the under side of the piston to make it as light as possible but keeping it reliable, also eyebrow the side of the piston on the transfer port sides to help with transfer. The 231 piston weighs around 19 grams and the 260 piston around 24 grams. This helps to let the engine rev up quicker. We also shape the piston skirt on the inlet side to give it a more progressive opening and closing system.

      The Result       

Over the past years OMEN RACE ENGINES have come up with an extremely fast and ultra reliable package that compares with any modified Zenoah engine on the market today. 

During this time Omen Race Engines has had some great results on the racing scene plus SAW time trials and quickly become a force to be reckoned with throughout Australia and world wide.

                 Visit Personal Currency Assistant™ to convert Australian Dollars to your Currency.

Omen Race Modified Zenoah G260PUM with WT-1048 Carb

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

The Zenoah G260PUM (25.4cc) marine engine features an improved cylinder design with 4 transfer ports, high rpm piston with a thin 1.0 mm single ring design, new improved combustion chamber shape that use a compact 10 mm spark plug. Includes genuine Walbro WT-1048 Carb.

-  Bore: 34.0 mm

-  Stroke: 28.0 mm

-  Displacement: 25.4 cc

Omen "BIG GAME" Full Race Modified Stroker 27cc PUM with WT-1048 Carb

The new Omen "BIG GAME" full race modified Zenoah 27cc PUM marine engine features the same high performance port work as the original Omen Race engine, but has the added extras of a Knife Edged +1.0 mm Crankshaft, Lightened Flywheel, Zero Drag crankshaft seals, Alloy Inlet Manifold and a Carb needle clamp.

With a good tune pipe and hull setup this engine can have you standing on the top step at the end of the day come trophy time, or give you that extra punch down the river to get you in front of your mates to gain bragging rights.

We start with a Zenoah G260PUM engine then add a +1.0 mm crankshaft to obtain a stroker 27cc race engine.

-  Bore: 34.0 mm

-  Stroke: 29.0 mm

-  Displacement: 26.4 cc

Omen Race Modified Zenoah G300PUM with WT-1048 Carb 

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

The Zenoah G300PUM (29.5cc) marine engine has the new Zenoah +1.0mm crankshaft factory installed.

Features an improved cylinder design with 4 transfer ports, high rpm piston with a thin 1.0 mm single ring design, new improved combustion chamber shape that use a compact 10 mm spark plug, genuine Walbro WT-1048 big bore carburetor, velocity stack plus E/Z Starter for effortless starting.

-  Bore: 36.0 mm

-  Stroke: 29.0 mm

-  Displacement: 29.5 cc

Omen "BIG GAME" Full Race Modified Zenoah G300PUM with WT-1048 Carb

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

The new Omen "BIG GAME" full race modified marine engine features the same high performance port work as the original Omen G300PUM Race engine, but has the added extras of a Knife Edged Crankshaft, Lightened Flywheel, Zero Drag crankshaft seals, Alloy Inlet Manifold and a Carb needle clamp.

With a good tune pipe and hull setup this engine can have you standing on the top step at the end of the day come trophy time, or give you that extra punch down the river to get you in front of your mates to gain bragging rights.

Features an improved cylinder design with 4 transfer ports, high rpm piston with a thin 1.0 mm single ring design, new improved combustion chamber shape that use a compact 10 mm spark plug, genuine Walbro WT-1048 big bore carburetor, velocity stack plus E/Z Starter for effortless starting.

-  Bore: 36.0 mm

-  Stroke: 29.0 mm

-  Displacement: 29.5 cc

Omen "BIG GAME" Full Race Modified Zenoah G310PUM with WT-1048 Carb

The new Omen "BIG GAME" full race modified Zenoah G310PUM marine engine features the same high performance port work as the original Omen Race engines, but has the added extras of a Knife Edged +2.0 mm Stroker Crankshaft, Lightened Flywheel, Zero Drag crankshaft seals, Alloy Inlet Manifold and a Carb needle clamp.

We start with a Zenoah G300PUM engine then add a +2.0 mm crankshaft to produce an absolute powerhouse stroker 30.5cc race engine.

With a good tune pipe and hull setup this engine can have you standing on the top step at the end of the day come trophy time, or give you that extra punch down the river to get you in front of your mates to gain bragging rights.

Features an improved cylinder design with 4 transfer ports, high rpm piston with a thin 1.0 mm single ring design, new improved combustion chamber shape that use a compact 10 mm spark plug, genuine Walbro WT-1048 big bore carburetor, velocity stack plus E/Z Starter for effortless starting.

-  Bore: 36.0 mm

-  Stroke: 30.0 mm

-  Displacement: 30.5 cc

Omen Race Modified Zenoah G320PUM with WT-1048 Carb

The long-awaited G320PUM. This performance beast features a 38mm bore and 28mm stroke for 31.8cc's of incredible performance. New for 2015. Features a new red anodized water jacket, improved pull start handle and lots more.

The 2016 full production version has a new design crankshaft & conrod assembly, two crankshaft bearings on the flywheel side and a new seal on the drive side.

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Note: G320PUM engine does not fit G260/300PUM engine mounts

Engine Specs: 
Displacement: 31.8cc (38mm bore x 28mm stroke) 
Carb: Walbro WT-1048 or Walbro WT-1107 
Spark Plug: NGK CMR7H 
Starter System: E/Z Recoil Starter

Omen "BIG GAME" Full Race Modified Zenoah 340PUM with WT-1048 Carb

The new Omen "BIG GAME" full race modified Zenoah G340PUM marine engine features the same high performance port work as the original Omen Race engines, but has the added extras of a Knife Edged +2.0 mm Stroker Crankshaft, Lightened Flywheel, Zero Drag crankshaft seals, Alloy Inlet Manifold and a Carb needle clamp.

We start with a Zenoah G320PUM marine engine then add a genuine Zenoah +2.0mm stroker crankshaft to produce an absolute powerhouse engine with an increased capacity of 33.9cc

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Note: G320PUM engine does not fit G260/300PUM engine mounts

Engine Specs: 
Displacement: 33.9cc (38mm bore x 30.0mm stroke) 
Carb: Walbro WT-1048. 
Spark Plug: NGK CMR7H 
Starter System: E/Z Recoil Starter

Omen "BIG GAME" Full Race Modified Zenoah G350PUM with WT-1048 Carb

The new Omen "BIG GAME" full race modified G350PUM marine engine features the same high performance port work as the original Omen Race engines, but has the added extras of a Knife Edged 2.8mm Stroker Crankshaft, Lightened Flywheel, Zero Drag crankshaft seal, Alloy Inlet Manifold and a Carb needle clamp.

We start with a Zenoah G320PUM marine engine then add a genuine Zenoah +2.8mm stroker crankshaft to produce an absolute powerhouse engine with an increased capacity of 34.9cc

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Note: G320PUM engine does not fit G260/300PUM engine mounts

Engine Specs: 
Displacement: 34.9cc (38mm bore x 30.8mm stroke) 
Carb: Walbro WT-1048. 
Spark Plug: NGK CMR7H 
Starter System: E/Z Recoil Starter

Omen Race Modified Zenoah G260PUM Cylinder Kit 

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Includes Omen Race Modified genuine Zenoah factory G260PUM 4-bolt 34mm 25.4cc cylinder, 34 mm piston, 34mm piston ring, water jacket o-rings, cylinder gasket, piston c-clips and piston washers.

Omen Race Modified Zenoah 27cc PUM Cylinder Kit 

Note: Must use optional Zenoah +1.0mm Stroker Crankshaft

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Includes Omen Race Modified genuine Zenoah factory G260PUM 4-bolt 34mm 25.4cc cylinder, 34 mm piston, 34mm piston ring, water jacket o-rings, cylinder gasket, piston c-clips and piston washers.

Omen Race Modified Zenoah G300PUM Cylinder Kit 

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Includes Omen Race Modified genuine Zenoah factory G300PUM 4-bolt 36mm 28.5cc big bore cylinder, 36 mm piston, 36mm piston ring, gold anodized water cooling jacket, water jacket o-rings, water jacket screws, cylinder gasket, piston c-clips, piston bearing, piston washers and wrist pin.

Omen Race Modified Zenoah G320PUM Cylinder Kit 

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Includes Omen Race Modified genuine Zenoah factory G320PUM 4-bolt 38mm big bore cylinder, 38 mm piston, piston ring, transfer port covers with screws, water jacket o-rings, cylinder gasket, piston c-clips, piston bearing, piston washers and wrist pin.

Omen Race Modified Zenoah 35cc PUM Cylinder Kit 

Note: Must use optional Zenoah +2.8mm Stroker Crankshaft

Includes modified intake, transfer & exhaust ports plus raised compression and lightened piston  (See top of page for details)

Includes Omen Race Modified genuine Zenoah factory G320PUM 4-bolt 38mm big bore cylinder, 38 mm piston, piston ring, transfer port covers with screws, water jacket o-rings, cylinder gasket, piston c-clips, piston bearing, piston washers and wrist pin.