Superhead 4V+R Bore & Stroke Up Kit SCUT 138cc Monkey Gorilla

【SP武川 01-06-8148 Superhead 4V+R Bore & Stroke Up Kit SCUT138cc for Monkey Gorilla - Big Bore Engine Parts Takegawa】
■Product Description
This kit includes a Superhead 4V+R head kit, cylinder kit, camshaft, and crankshaft kit (with Diehard α cam chain and stud bolts).
SCUT138cc. 2-point support crankshaft.
Bore diameter 57mm. Stroke amount 54mm. Compression ratio 12.6:1.
Included camshaft: 20/25D
No crankcase machining is required.

■Detailed Description
●Features of Superhead 4V+R (1 Cam 4 Valve)
Compared to SP Takegawa's Superhead+R large-diameter 2-valve, increasing the intake and exhaust valves to two each further expands the valve curtain area, allowing for higher intake and exhaust efficiency than large-diameter 2-valves.
Additionally, due to the cylinder head design, which incorporates a center plug, valve angle, combustion chamber shape, and port shape balanced for 4-valve conversion, it achieves high output and the sustained high-rpm output characteristics that are the hallmark of the Superhead.
By adopting a 1-cam 4-valve system, we have achieved the greatest possible weight reduction and compactness, while simultaneously condensing the performance of the strongest SOHC head.
●New Superhead 4-Valve+R Body
The rounded cylinder head shape perfectly complements the Monkey style, enhancing the custom image of the vehicle.
Furthermore, each die-cast head cover, which has undergone barrel polishing, beautifully enhances the cylinder head.
●Valve Features
Valve diameter: Intake: 21.5mm x 2 / Exhaust: 18.5mm x 2
Valve stem shaft diameter: Intake and exhaust are both 4.0mm.
●Valve Springs
Asymmetrical pitch is used to prevent surging at high RPMs.
●Features of IN/EX Ports
The port diameter is optimized to match SP Takegawa's 3D-shaped manifold.
Furthermore, by installing it simultaneously with the 3D-shaped manifold, it enables smooth, unobstructed intake from the carburetor to the combustion chamber, maximizing the performance of the cylinder head.
●Adoption of Roller Rocker Arm
By adopting roller rocker arms, the Superhead+R's output performance is maximized, increasing output in the mid to high-speed range and sustaining output at high RPMs, which is a characteristic of roller rocker arms.
Roller rocker arms reduce frictional resistance with the camshaft, which occurs with slipper-type rocker arms (OEM type), and the roller bearings built into the rocker arm allow the cam profile to be smoothly followed from low to high RPMs.
●M8 Spark Plug
An M8 spark plug is adopted due to the optimal valve angle resulting from the 4-valve design and the compact size of the head.
●Hollow Camshaft with Oil Jet (Auto Decompression)
An oil line is provided in the center of the camshaft to guide oil to the cam sprocket.
This improves the durability and lubrication effect of the cam chain.
Additionally, an oil jet passage is provided on the cam surface of the camshaft, allowing oil to be sprayed from the cam surface onto the rocker arm, effectively providing cooling and lubrication.
The camshaft journal features ball bearing support at both ends, reducing frictional resistance to the camshaft during startup and at low speeds.
Auto decompression function: Allows engine startup with light kicking force, even for large displacement engines.
●Ceramic Plated Cylinder/Piston
The SCUT structure of 138cc is patented.
Bore diameter 57mm. Features an all-aluminum ceramic-plated cylinder with excellent durability, airtightness, and heat dissipation.
The cylinder comes standard with a temperature sensor mounting point. By purchasing an SP Takegawa thermometer-equipped meter or thermometer, you can measure the cylinder temperature.
For SCUT 138cc: C1 adapter + M5 temperature sensor
The SCUT cylinder is equipped with an oil jet mechanism (patent pending).
The oil jet cylinder is a cylinder that can spray oil onto the cylinder and piston by simply replacing the cylinder, without the need to replace the crankcase, disassemble the crankcase to process oil spray holes, or add parts for oil spraying.
By providing oil spray holes directly on the inner surface of the cylinder, continuous oil spraying is possible on the piston skirt and piston inner wall during engine operation, enabling efficient lubrication and cooling.
The 138cc uses a cast piston.
The piston skirt is coated with molybdenum for better initial break-in.
*Forged pistons are available as optional parts for the 124cc.
●2-Point Support Crankshaft
To accommodate high-power engines, a special bearing with an enlarged inner diameter for the journal bearing of the long-stroke crankshaft (54mm stroke) is adopted.
This allows the shaft diameter of the journal part, where stress concentrates on the crankshaft, to be increased from 20mm to 22mm, improving strength.
Furthermore, special surface treatment on the crankshaft further enhances durability.
Stroke amount: 54mm

■Compatible Models
HONDA
12V Monkey/Gorilla (Z50J-2000001 to) (AB27-1000001 to 1899999)

■Notes
*Images are for illustration purposes only. Includes products with different sizes and colors.
*Product designs and specifications are subject to change without notice. Please understand.
*When installing 124cc/125cc/138cc, the engine length will increase, and the engine will interfere with the tire if using standard front forks and standard top bridge & stem, so changes to the front area are required.
*For Monkey/Gorilla. Simultaneous installation of various SP Takegawa front fork kits is recommended.
*For CRF50F/XR50R and CRF70F/XR70R. SP Takegawa does not sell front fork kits or similar products. Also, while aftermarket frames and front fork kits are available, SP Takegawa does not confirm installation with simultaneous use. Please install on your vehicle at your own risk.
*SP Takegawa Dig Crosser mufflers cannot be installed simultaneously.
*As this product is made-to-order, cancellations after ordering are not possible.
*This is a made-to-order product, so delivery may take some time. Also, please note that the manufacturer may discontinue the product or change specifications without prior notice.