[Honda Dax 125] Increased from 9 HP to 15 HP! 145cc Bore-Up + SOHC 4-Valve Head, the Ultimate Model | STEP 3 (Advanced) - Motopeek - Latest Motorcycle News, Reviews & Updates

Special Parts Takegawa’s beginner-friendly engine tuning for stock 123cc STEP:1 (Beginner)

What is an engine bore-up? Easily increase maximum power output with a commercially available kit! Special Parts Takegawa proposes engine tuning techniques from stock 123cc to 145cc | STEP 2 (Intermediate)

Revolutionary 4V (valve) design with two intake valves and two exhaust valves on one camshaft

The genuine Dax 125 cylinder head is a two-valve design with one intake valve and one exhaust valve on one camshaft (SOHC). The cylinder head below is an innovative four-valve design with two intake valves and two exhaust valves on one camshaft (SOHC).

The key features of the SOHC 4-valve engine, which can be called the pinnacle of SOHC, are:

・Compared to a two-valve system with one intake and one exhaust valve, it allows for smoother intake and exhaust flow across the entire engine range.
・The cylinder head itself has a lightweight and compact shape that is unique to a single cam (SOHC) system.

The kit below not only uses the tuning technique introduced in “STEP:2 Intermediate Edition” to increase the displacement from the stock 123cc to 145cc, but also incorporates a high-performance SOHC 4-valve cylinder head. The synergistic effect of these two components has succeeded in achieving monster power that far surpasses the stock version.

Super Head 4V+R Combo Kit 145cc… 269,500 yen (tax included) Part number: 01-05-0649

Compatible models: Dax 125 (JB04/JB06-1000001~)

The displacement has been increased from the stock 123cc to 145cc, and the cylinder head has been modified to a 4-valve specification that provides excellent intake and exhaust efficiency. By incorporating the parts listed below that make up the kit, you can achieve monster power that surpasses the entry-level “Hyper Tuning Set (Big Throttle Body included)” and the intermediate level “Hyper S-Stage Bore Up Kit 145cc”.

Super Head 4V+R Bore Up Kit 145cc

The Super Head 4V+R (1 cam, 4 valves) cylinder head has two intake valves and two exhaust valves (compared to the standard 2-valve head with one each), which allows for a larger valve curtain area and improves intake and exhaust efficiency beyond that of a large-diameter 2-valve head.

In addition, the cylinder head shape has been designed with a careful consideration of the balance between the center plug, valve angle, combustion chamber shape, and port shape required for the four-valve configuration, resulting in high output. The Super Head’s greatest feature is its sustained output characteristics at high rpm. By adopting one cam and four valves, it has been possible to make the engine as light and compact as possible, condensing the strongest performance of an SOHC engine.

Super Head 4V+R (1 cam 4 valve) cylinder head: Here are the key points!

Roller rocker arms with built-in bearings, just like the original

. This reduces friction with the camshaft. The roller bearings built into the rocker arms allow the camshaft to follow the profile smoothly from low to high RPM.

Valves → Intake

21.5mm x 2 / Exhaust: 18.5mm x 2

Valve stem shaft diameter:

4.0mm for both intake and exhaust

The valve spring

uses an unequal pitch (two-stage pitch) single valve spring to prevent surging at high revolutions. The port diameter is optimized to match the manifold for the special Takegawa big throttle body.

In addition, by simultaneously installing a manifold for the big throttle body made by Special Parts Takegawa, smooth intake is possible from the big throttle body to the combustion chamber without resistance, maximizing the performance of the cylinder head.

The original cylinder head shape from Takegawa Special Parts matches the style of the vehicle and enhances the custom look. The inspection cover and left cylinder head side cover are made of aluminum die-cast with a barrel polished finish.

Furthermore, the oil tower on the R side of the cylinder head is made of machined aluminum with silver anodized finish. The various covers and oil tower have an excellent dress-up effect, creating a beautiful cylinder head.

● M8 spark plugs

have been adopted due to the optimal valve clamping angle and compact head achieved by using four valves.

Auto-decompression camshaft (10/10D)

The camshaft is supported on both ends by ball bearings, reducing frictional resistance in the camshaft journal. The auto-decompression mechanism reduces the force of the kick start and the strain on the transmission when starting the engine, allowing for smooth engine starts even with a large displacement.

The cylinder

features an aluminum steel sleeve cylinder. The bore diameter is Φ54mm, the stroke length is 63.1mm (standard), and the compression ratio is 12.0:1. The cylinder can be fitted with a special Takegawa M5 temperature sensor. Cylinder temperature can be measured by purchasing and installing a separate thermometer (compact LED thermometer with M5 temperature sensor).

●Piston

The piston body is precisely machined from cast aluminum, resulting in a lightweight yet highly rigid finish.

※スーパーヘッド4V+Rボアアップキットを装着した場合、FIコン TYPE-X(インジェクションコントローラー)の同時装着が必要。
※排気量が125cc以上になるため、原付二種登録では一般公道を走行することは不可。競技専用。

・スーパーヘッド4V+Rボアアップキット装着に関して
スペシャルパーツ武川製ボアアップキットの装着により、エンジン出力、トルクが大幅にアップするため、クランクシャフトには、ねじれやたわみ等の負担が増加します。SP武川では、クランクシャフトの負担をを軽減させる為、クランクシャフトサポートアダプターの同時装着をお薦めします。クランクシャフトサポートアダプターは、クランクシャフトフライホイール側末端にボールベアリングによる支持を追加することにより、ねじれやたわみ等を抑え、クランクシャフトの耐久性を高めます。

●ダックス125(JB04/JB06)用クランクシャフトサポートアダプター 品番：01-10-0150
商品の公式WEBサイト　http://www.takegawa.co.jp/products/detail.php?product_id=4738&category_id=2696

Big throttle body kit Φ34 (for stock cylinder head)

A unique big throttle body kit developed for Special Parts Takegawa engine parts. By adopting a Φ34mm big throttle body, the performance of Special Parts Takegawa engine parts is maximized, resulting in increased power output.

It can be compactly stored around the engine, and can be installed without ruining the silhouette of the vehicle. No modification of the cowl or wiring is required, and it can be installed with a bolt-on. An air filter with excellent intake efficiency is also included. *Cannot be used with a stock engine.

FI CON TYPE-X (injection controller)

This injection controller can be attached to the stock ECU via coupler-on. It comes with preset MAP settings to suit each engine specification. Simply select the MAP that matches the specifications of the bore-up kit or throttle body you are using on your smartphone or computer to complete basic operations and get ready to ride.

It is designed to be fully usable by even advanced users, allowing you to customize settings based on existing maps or create new maps. Connecting to a PC or smartphone while the engine is running allows for a convenient tachometer screen for easy settings. It also displays a throttle opening graph. Engine temperature monitoring is also possible. It also has a rev limit function. It can be installed simultaneously with the Honda genuine immobilizer alarm.

FIコン TYPE-Xをご使用の際には条件に適合したパソコンもしくはスマートフォンが必要になります。条件をご用意頂けない場合はご使用になれません。又、ソフトやアプリのダウンロードが必要になる為、インターネットに接続されている必要があります。
アプリの場合、有料となります。予めご了承下さい。

FIコン TYPE-X機能の詳細、条件は下記リンクボタンをクリックしてご確認下さい。
FIコン TYPE-X詳細ページはこちら

Large-capacity injector (G-1)

When equipped with an S-Stage Bore Up Kit 145cc, sports camshaft, FI-Con TYPE-X (injection controller), and big throttle body kit. The stock fuel injectors do not inject enough fuel to handle the increased intake air volume, so they are replaced with these large-capacity fuel injectors.