Desmodromic Twin Cam 4V Complete Engine 124cc (DESMO-4V)

■Desmodromic 4V
The desmodromic mechanism forcibly opens and closes the valves by means of specially shaped camshafts and rocker arms, and since there are no valve springs, surging does not occur at high RPM and the friction involved in camshaft drive is very small.
The characteristics of the desmodromic mechanism combined with SP Takegawa's cylinder head development technology have achieved the highest class intake and exhaust efficiency and high engine performance.

Valve Diameter Intake: 22mm x 2 / Exhaust: 19mm x 2
Rocker arm (forced valve opening / closing mechanism):The valve opening and closing is forced by the camshaft without the valve spring.
Compared to the valve spring type, it reduces the resistance of the valve train and eliminates valve surging that occurs at high RPM, resulting in high power output and engine response at high RPM.
The exhaust port is in the same position as that of the Monkey (carburetor type) so that the standard lineup of exhausts can be used instead of a special exhaust.
The M8 spark plug is used for the optimum valve pinching angle and compact head.Machined aluminum cylinder head cover.

■Forced-open camshaft
The camshaft of the forced valve opening / closing mechanism is equipped with camshafts that perform independent actions of "opening" and "closing".
The camshaft journals are supported by ball bearings on both ends to reduce frictional resistance to the camshaft during starting and at low speeds.
The camshafts supplied with the kit are the recommended camshafts for each engine displacement.

■Displacement can be selected from 124cc or 138cc.

■Ceramic plated cylinder (patented SCUT structure for 125cc/138cc) & piston
Adopts all-aluminum ceramic plated cylinder with excellent durability, airtightness and heat dissipation.The cylinder is equipped with a temperature sensor as standard.
You can measure the cylinder temperature by purchasing SP Takegawa's thermometer built-in meter or thermometer.
HA cylinder for 124 cc: M5 temperature sensor, SCUT cylinder for 138cc: C1 adapter (07-04-0031) + M5 temperature sensor
Piston: The 124cc model uses forged pistons.Cast pistons are used for the 138cc model, and the piston skirts are coated with molybdenum to ensure good initial fit.


■Crankshaft
Special bearings with a larger inner diameter for the journal bearings of the stroked crankshaft are used to accommodate high power engines.
The shaft diameter of the journal section, where the stress of the crankshaft is concentrated, is 22mm to improve strength and durability.The crankshaft is also given a special surface treatment to further enhance durability.

X-shaped connecting rods are used for the 124cc crankshaft.It is lightweight and strong enough, and its buckling stress diffusion and torsional rigidity are greatly improved.

■Secondary type kick starter system with crankshaft support adapter
Crankshaft journal section is changed from a 2-point support to a 3-point support to reduce crankshaft shaking that occurs at high output and high RPM and to increase crankshaft durability.
Generator cover included for crankshaft support adapter

■Newly designed SP Takegawa original reinforced crankcase
The SP Takegawa reinforced crankcase is a high quality crankcase that is specially designed in every detail to increase rigidity to cope with the added stress on the crankcase caused by the larger displacement.
The oil pump is a crankshaft direct drive super oil pump (with relief valve function).
The relief valve mechanism enables hydraulic pressure control and maintenance of proper oil quantity and oil level.
The breather pipe has an inner diameter of 6mm compared to the stock inner diameter of 4mm to reduce the internal pressure of the crankcase in large-displacement engines.
The crankcase itself is equipped with an oil jet mechanism that constantly injects oil directly onto the small end of the connecting rod and the backside of the piston for lubrication and cooling.
The transmission bearing is equipped with a special bearing hold plate for big torque.
*The Desmodromic 4V complete engine is only available with a secondary kickstarter system.

■Super cam chain tensioner
It follows the cam chain and maintains the proper tension.The tensioner arm is machined from high-strength super-duralumin material and its thickness is increased to strengthen the arm body and further increase the contact area to the push rod.
An oil hole is provided in the arm to lubricate the operating part.
The surface is hard anodized.

■Adoption of secondary type kickstarter system

■Special Clutch Kit for Secondary Type Kickstarter System TYPE-R (WET/DRY)
The TYPE-R has been downsized to reduce the rotating mass weight by approximately 12%.6 friction discs are used to achieve a 6-disc reinforced clutch.
As a result, the clutch capacity is increased by approx. 20% compared with the standard product, and it is applicable to high power engines.The clutch is without a slipper clutch mechanism.
The right crankcase cover is made of die-cast aluminum with a silver paint finish. Both WET and DRY are available in wire or hydraulic types.

The wire type uses a light and smooth rack and pinion system.Clutch cable 850mm included.
Hydraulic type includes clutch master cylinder, mesh hose (775mm) and banjo.
WET (wet): The wire type clutch cover is made of forged aluminum with a shot finish, and the hydraulic type clutch cover is made of machined aluminum with a clear anodized finish.
DRY (dry): Both wire and hydraulic clutch covers are machined from aluminum with a clear anodized finish.
The clutch cover for DRY (dry type) has more ventilation holes for better cooling effect.A set of rubber caps (sold separately) can be attached to the ventilation holes to prevent noise characteristic of dry-type systems.
With TYPE-R you can route oil to the oil cooler by installing the oil cooler unit (sold separately).


■TAF 5 Speed Cross Transmission (S Touring)
It has high durability and excellent operability.The complete engine uses the S Touring gear ratio.

■Super Street Outer Rotor
Capable of stable high power output for both street and racing use, while providing the same brightness of lights required for street use and a charge level that compensates for power consumed while riding.
The SP Takegawa rotor body uses a medium size flywheel that is approximately 50% lighter than the standard flywheel to reduce the load on the crankshaft while achieving “ease of riding and necessary power generation” and enabling high output characteristics and response.


■SP Takegawa original aluminum die-cast generator cover
The secondary type is buffed and clear coated on the aluminum surface.Also, the sprocket can be replaced without removing the generator cover.
The generator cover for the secondary type has an integrated bearing for the crankshaft support adapter.

■Hyper C.D.I. included. Ignition characteristics suitable for SP Takegawa engine parts.

■Complete engine recommended parts

■Change to a big bore carburetor is required. A change to a Desmodromic 4V cylinder head and an increase in displacement requires the separate purchase of a big bore carburetor kit to maximize the engine's performance.
It is.SP Takegawa carburetor kit includes a carburetor, special manifold (insulator) and high throttle set (FCR/TMR downdraft only).
You can choose from 4 types of carburetors, MIKUNI VM26, KEIHIN PE28, KEIHIN FCR downdraft and MIKUNI TMR downdraft.Please refer to the web catalog for various kits.

■Change to an SP Takegawa exhaust with excellent exhaust efficiency
In order to get the best performance out of the engine, it is necessary to change to an exhaust with excellent exhaust efficiency.The Desmodromic twin cam 4V cylinder head has the exhaust port in the same position as that of the Monkey (carburetor type) so that the standard lineup of exhausts can be used instead of a special exhaust.