Loading... Please wait...
  • +66 (0)80 600.53.36.
  • Gift Certificates
  • My Account 



Posted by

this link to visit this product page)

● This cylinder kit is mentioned for anyone who want to upgrade to a 175cc with dome piston, and a 150 head.

This kit comes with the 62mm dome piston, 13mm piston pin, a 62mm cylinder with water canals that fit with the 150 head, 62mm gaskets, and very important, a standalone ECU and the correct size of injector in the box!

The set comes also with the Yuminashi double progressive valve springs, and the lighter then stock retainers, which makes again a gain in horsepower and RPM's.


● The big valve STD150-Head comes complete with the larger 28mm/23mm valves, seals, nuts, bolts and everything necessary to make the install possible your 125 engine.
This larger cylinder head replace your original 27mm/22mm Honda cylinder head to make the install of the 62mm high compression dome piston possible.


● Taking tuning to the next great leap with adding the YUMINASHI STANDALONE ECU in the 175cc DOME ULTRA PACK for PCX125 LED & SMART KEY.


At YUMINASHI, we understand that a fully standalone for the PCX engines are not technically possible because unlike other bikes, the Engine Control Module (ECM) for these engines contain also the starter function as well as battery recharge.

This problem has prevented the emergence of a stable, truly open source standalone ECU for the PCX engines for years.
However, we have solved this problem with a special wire loom in order to let you connect a true standalone ECU to your stock wire harness.
Please be noted that your stock ECM would still need to be installed in order to start the bike and recharge the battery. The rest, however, is fully controlled by you, the tuners through our standalone software.

Since this is a standalone ECU, the RPM limit will be removed, and you the tuners have full control over almost everything. Injection control, both the amount and the timing of the injection event as well as ignition timing, and enrichment circuits to compensate for cold engine start are all available to tuners who want to take advantage of them and allow for a much more precise tuning experience which will undoubtedly lead to a better running engine and higher performance.

You will need to buy a wideband O2 gauge as well as this optional data link cable (if you want to physically connect the ECU to your laptop or PC) or to bring your scooter to a dynamometer service which can perform air fuel ratio tuning in order to take the most advantage of this standalone ECU unit.

This Standalone ECU is Bluetooth enabled!
If you have an Android phone, you can use Bluetooth to tune the setting yourself!..

If you want to get your tune absolutely right, then we recommend to install a Wideband O2 Gauge like the Innovate MTX-L gauge.

The Air Fuel Ratio (AFR) below 75% TPS throttle can be 14.7 AFR for good fuel economy, we recommend with WOT (Wide Open Throttle) 12.3AFR.


● The Torque Control Variator Set in the package which will improve both, acceleration and top speed.
The 8 gram roller weights are included in the set.


● The 35mm throttle body is 40% larger compared to the stock PCX125 throttle body, and the reason why this much larger throttle body is included in the kit is because the stock throttle body is a serious restriction for the much larger amount of air sucked in by the 175cc dome big bore piston. Removing the stock throttle body and replacing it by the 35mm throttle body allows the engine to suck as much air in as possible, and opens the full potential of your engine in combination with the big bore kit.


● The special throttle cable 17910-KWN-910 for the 35mm throttle body comes with the set together with the 5-Pin Wire Loom to make the install a truly plug & play experience.

17910-kwn-711.png 32101-k36-000-5-pin-connector-loom-pcx150-led-.png

● The 6-Holes B-Type High Flow NLJ-injector is included in the kit for the simple reason that sucking more air in the engine with a much larger piston and a 25% larger throttle body requires more fuel to keep the perfect balance between air and fuel.
This is important of course for the performance of the engine, but also for the reliability since a lean running engine would have overheating issues. Selecting the right injector is really important and with including the right injector in the kit you can be ensured your engine gets the fuel it needs to get.

**With the standalone ECU you can adjust the fuel amount to get your Air Fuel Ratio based on your location, humidity and altitude really spot on. Barometric pressure is highest at sea level and decreases with altitude. A reduction in atmospheric pressure requires leaning the fuel mixture.


● The 31mm B-Type Manifold Set is included in the kit to make the install from the injector and the throttle body a truly plug and play experience. The stock injector joint from the PCX125 can be installed on this manifold and injector to connect your fuel hose.


● The 1.6 High Pressure Cap which comes with the set is to make sure your cooling system can control the extra power and doesn't open premature at 0.9 bar. All cool details about the protection from this cap can be found over there (recommend to read!).


● The 175cc, 62mm dome piston with 13mm piston pin in this kit will make sure your engine will produce more power in a very balanced way without engine knock...

The 175cc Dome Piston is made just like all other Yuminashi pistons from AA-Grade aluminium and finished with a black molybdenum coating on the sides of the piston. The piston from this 175cc Dome Ultra kit has been developed to work in combination with the larger valves 150 head.

The valve pockets in the piston are machined deeper compared to stock, and allow a 0.05mm IN / 0.08mm EX valve clearance.


● The high grade Yuminashi piston rings are developed and produced by very strict Japanese standards and all rings are treated with a hard chromium plating layer (Cr). All details about the piston rings can be found over here.


● The YUMINASHI Billet CNC X250RR Camshaft Kit comes also with the ULTRA kit, and this cam is the hot ticket for getting the most out of your PCX125 V1 engine.

This Yuminashi camshaft is designed in conjunction with our racing efforts, and in turn the design gets passed down to our customers for the best power gains.

Yuminashi R&D designed this camshaft to be used in combination with the stock 125cc valves, with an increased lift and duration to produce a potent curve with solid torque to red-line.
This means when you whack open the throttle out of a corner, you'll get a nice hit off the bottom all the way to the top!

All Yuminashi camshafts come standard with high-speed NACHI JAPAN C3 bearings to meet our standards concerning durability and reliability.

These high-end bearings can run exteme high RPM's, where the C3 stands for an optimal clearence with less friction at operating temperature.

The 2 special tappet adjusting bolts come with the camshaft in the kit because with the high lift of the camshaft it's not possible to use the stock tappet adjust screws.

**The valve clearance is 0.05mm IN / 0.08mm EX.


● The stock 125cc and 150cc eSP 12.95mm roller diameter is adequate for all stock camshafts, but high performance engines with high lift camshafts benefit from larger diameter rollers for the simple reason that the larger face of the 16.9mm rollers accept a more aggressive lobe profile before the roller digs into the cam lobe, which of course leads to nearly instant camshaft failure.

Therefor the rocker set with larger, more durable rollers comes together with the 164 ULTRA kit to ensure increased durability and reliability.


● The special Yuminashi SPL Tappet Adjusting Screws which comes with the set will need to be installed if you install a high lift camshaft.

The stock Honda screws are shorter and you will face a problem to lock the stock tappet adjust screw.

The Yuminashi SPL Tappet Adjusting Screws have a groove to make easy adjustment possible.


Keep in mind that installing a high performance camshaft with more lift and duration might affect the operation of the ISS Idle Stop Start system.

The Progressive Double Valve Spring Conversion Set comes with the ULTRA Light Bore Kit for the power aspect, but also for the safety aspect since your engine has no RPM limiter anymore once the PMF-FI Controller is installed, and these double valve springs eliminate the chance on floating valves at high RPM entirely.

This kit includes 2 outer valve springs, 2 inner valve springs and 2 lighter as stock steel 5mm valve retainers to make a complete conversion from the stock single valve springs in to a double valve spring setup possible…


● The CR10EK Nickel Multi-Ground spark plugs have been tested in combination with the Yuminashi 164cc light bore kits, and the results are a cooler running engine with improved combustion, and clearly less sensitive for engine knock.

Multi-Ground Electrodes Improve Ignition Capabilities and Are Less Sensitive to Increased Voltage Requirements Due to Gap Growth.


● The 175cc Flat Deck Cylinder is pure racing DNA from the YUMINASHI PRO-SERIES.

The Flat Deck cylinder has larger water/coolant capacity, and is developed by the Yuminashi R&D to have a cooler running engine.

With the flat deck design you are able to run higher compression ratios without the fear of blowing head gaskets. A very hard cylinder sleeve has been installed which comes directly from the Yuminashi racing series engines to avoid ovalisation, oil leaks and compression loss!...

This specific cylinder block 12100-KWN-620X has been prepared to be plug & play ready for the first generation PCX125 crankcases. The crankcase bore is smaller from the first generation PCX125 compared to the eSP PCX125's, so the cylinder has been developed in such a way to make a plug & play install possible.

This cylinder block comes also with the 3 pins to connect the stock ignition coil bracket on the cylinder, which is also unique for the first generation PCX and with a 125cc mark on the cylinder so that there isn't any difference compared to stock once the cylinder is installed on the engine.


● The special copper 0.3mm gasket set is made to make a perfect fit with the stock 150 head in combination with a 62mm bore on the PCX125 LED / SMART KEY. These copper gaskets come with the kit to make sure your engine makes the perfect seal. (Click the image below for more information)


● The large diameter Big Tube Air Intake Set for the 35mm throttle body which comes with the kit make sure your engine get's the air it needs to make the most power out of it, (more information and pictures can be found over here).

Keep in mind that the diameter of the hole in the stock PCX125 air filter box will need to be modified, and the length from the Big Tube Air Intake will have to be shortened based on your needs.




- THE PCX125 LED (2014-2015)
Y (2016-2017)

What's News


Copyright 2019 YUMINASHI DIRECT SALES. All Rights Reserved.
Sitemap | Bigcommerce Premium Themes by PSDCenter