Engines/motors

Found this beauty on futureworldmodels.com for around £340...

Speed-tuned for championship-caliber performance!

Countless champions, including Mark Pavidis and Atsushi Hara, have trusted O.S. Speed engines to give them a competitive edge. Now, O.S. is proud to continue that winning tradition with the 21XZ-B Speed! A specially designed black-anodized cylinder head improves cooling and reduces weight, while an upgraded, DLC-coated crankshaft improves fuel flow. It all adds up to yet another exceptional, Speed tuned engine from O.S.

Unparalleled, speed-tuned power characteristics.
Lower fuel consumption – offering 8% longer run times than the former model, 21VZ-B V-Spec Speed.
Race-proven 3-port sleeve with special Speed version inner head and porting for smoother acceleration.
Tough, DLC-coated crankshaft features a silicone-filled intake passage for improved fuel flow.
New 21J2(B) three-needle carburetor includes 6 mm, 6.5 mm and 7 mm restrictors for fine-tuned control.
A lowered center of gravity provides steadier vehicle handling.
Long stroke allows for superior torque.
A black anodized crankcase with ceramic ball bearings helps reduce resistance and increase performance.

Here's a bargain engine found on bmmracing.co.uk. You can have it on its own for £125 or as a kit with a tuned pipe for around £160.

From Go Engines are the GX Series, having undergone significant development around the world with some very respected engine developers this is the result.

 Never at any point has any engine offered these features at this price. Using a TiNi hardening treatment on the crank and gudgeon pin makes the engine truly rebuildable as well as reducing friction and increasing rpm. The same treatment is used on the carb slide to give a smooth movement throughout the operating temp range of the motor.

 Revised porting on the liner and crank timing make this much more driveable whilst not hurting power delivery and increasing run time. Turbo head button and T3 Turbo Plug also included. NB The T3 is the default plug for these engines.

 All New lightweight drilled head reduces weight and CofG whilst also improving heat dissipation.

 3Pt Gives the smoothest powerband of the 3 new GX Series Engines.

 Includes 4pc Carb Venturi Set to alter power delivery of engine

 Recommended pipe is a Go EFRA 2072 Pipe

GX-73
-- Size 3.45cc
-- Maximum Power 2.7hp
-- R.P.M 37.000 rpm
-- Practical Range 6.000/44.000rpm
-- Bore/Stroke 16.26mm/16.80mm
-- Ports 3+2 -- Crankshaft 14mmSG
-- Carburettor 8mm
-- Glow Plug T3 Turbo
-- Exhaust Type Rear.
-- Included in the box a Turbo glow plug T3, a second Con-rod, Go EFRA 2072 Pipe(optional at extra cost) and a complete carburettor restrictors set!!!

This is the RB WS9 engine on bmmracing.co.uk for £260.

Many times World Champion, the world series 09 version. RB made this engine even more adapted to the Off Road class needs by adding the Multi Exhaust System. The strength of the WS9 engine is its smooth from low RPM, making this very high level engine reachable to all.

Features

Very high level racing engine
7 ports + 3 Multi Exhaust System (MES)
Turbo plug
Turbo combustion chamber
Bi-turbo 13mm crankshaft+Concept Coating(square stroke)
13mm main bearing and double rubber seal located on the front side of the front ball bearing
Nylon 9mm carburettor with 6, 7 & 8mm Venturi included
Light Off Road L2G cooling head (17g lighter)
Aluminium orange anodized carburettor wrist pin
Dust protection caps for carburettor, exhaust, fuel intake and top of the crankshaft

Spec Check

Contents: 3.49 cc
Bore: 16.42mm
Stroke: 16.42mm
Porting intake: 7
Porting exhaust: 3 MES
Crankshaft: 13mm Bi-Turbo+ RB CONCEPT COATING
Carburetor: Slide Composite 9mm with removable Venturi 6,7,8mm
Glowplug: Turbo #01051-6
Weight: 348 Gr.

A member recommendation here is the Argus A52 .21 5+2 Port turbo competition engine, with very good reviews throughout the web and at a fantastic £120 on m-k-racing.com

This engine has been manufactured to Argus's exacting standards by the leading Taiwanese engine manufacturer on their multi axis cnc machines, already with a proven reliability and performance record. The original manufacturer of these engine's has already achieved remarkable results in the last 12 months by taking the win at the "pre-Worlds" race in Thailand.

The Argus engine features a revised carburettor, timing and porting to Argus's exacting requirement's to achieve excellent power and drive ability, all achieved at a VERY reasonable price.