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● 167CC GT220 CYLINDER KIT, HIGH COMPRESSION (eSP+ 125CC/150/160 ENGINES) (12100-K0S-V62R)
● The one thing the old EURO-4 Forza125 4-Valve, and the new EURO-5 125, 150 and 160 eSP+ 4V engines have in common, is that they are all sharing the same 20mm intake and 17mm exhaust valves.
● So if Honda decided in 2015 that the 17/20mm valves are the correct size to be installed in the 125cc 4V engines, then you have to ask yourself how come these same 125mm valves are then used in the 160cc engines? And more importantly, how can we correct this to get it right?
● CALCULATION / COMPARISON:
● We can take a look to the older generation 2-valve engines to answer the question about how to get it right, because we know that the Ø22/27mm valves did a great job on the 2-Valve PCX125 engine, and the Ø23/29mm valves on the 2-Valve PCX150 engine with a 58mm piston, so this will make it easier to compare.
● If we take a look to the surface area for 2 times Ø20mm intake valves, then we get 2 times 314.6mm² which equals 628.32mm², or 1 intake valve of Ø28.28mm.
If we do the same for the exhaust valves, then the surface area of 2 times Ø17mm valves equals 103.76mm², or 1 exhaust valve of Ø24.04mm.
So based on this calculation we see a single Ø28.28mm intake valve as result, and this is larger compared to the formal PCX125 27mm intake valve, but it's actually smaller compared to the formal PCX150 29mm valve with the 58mm piston.
If we take a look to the calculation result of the exhaust valve, then we see that a single Ø24.04mm exhaust valve is larger as both the 22mm PCX125 and 23mm PCX150 valve before.
A 2-valve 125cc engine with 28/24mm valves can actually perform really well with a 125cc, and we know this based on the results of the 2-valve CBR125R which has a 58mm dome piston and the 28/24mm valves combination, but we don't think that this is a good choice for a 160cc engine with a 60mm piston or larger...
● SOLUTION:
● By installing the YUMINASHI GT220 CYLINDER HEAD (LINK) and this 62mm GT220 CYLINDER KIT (12100-K0S-V62R) with the flat piston, you're not you're not only getting a 167.47cc engine instead of a 125cc engine, but you are getting 2 larger 22mm intake valves, and 2 larger 19mm exhaust valves with a higher compression ratio piston.
● 2 Intake valves of 22mm equals a single 31.11mm intake valve, and 2 exhaust valves of 19mm equals a single exhaust valve of 26.87mm.
Our recommendation to use the 32mm throttle body and manifold is totally based on the intake valve size, because this makes perfectly sense and you are not "overdoing" things.
※ If you have a 160 engine (which is called 150 in the US), then you don't need to order the entire cylinder kit to run the big valve GT220 head, you can just order the GT220 head together with the GT220 60mm piston (LINK) and install it on your stock cylinder with a new head gasket (LINK)...
※ We recommend to install the 155cc B-type 6-holes injector (LINK) in combination with this 160cc cylinder kit and the big valve head.
※ This cylinder head need to be installed with the large diameter cylinder gasket (LINK), and recommend to install a exhaust header with 28mm inner diameter.
※ Recommend to install a 32mm throttle body & manifold set.
Torque Spec for the cylinder head nuts are: Torque 27 N m (2.8 kgf m, 20 lbf ft)
● PISTON DETAILS:
● The piston you get in the 160cc YUMINASHI GT220 high compression kit is not only a higher then the stock 160 piston with larger valve pockets for the GT220 cylinder head, but also a lighter piston compared to stock, where the valve pockets are prepared to run a high lift performance camshaft.
● The hard chromium plating layered (Cr) piston rings which come with the set are produced by very strict Japanese standards and has excellent characteristics which combine the original properties of chromium metal with the advantages of erector-deposits!
The main benefits from the chrominum plating layered piston rings are extremely high hardness of HmV (Micro Vickers), 800 to 1100 (cf. gray cast iron 220 to 270), high melting point of approx. 1800°C (cf. cast iron 1200°C), good thermal conductivity and corrosion resistance, a low friction factor and excellent wear resistance, such features are very effective in preventing piston ring wear.
● The enlightened piston is made from A-grade materials and the piston skirts come with a molybdenum coating. The Anti-detonation grooves on the top ringland provide several advantages, which include further atomization of the combustion charge to prevent damage to the piston and ring caused by pre-ignition. These grooves also prevent carbon build up on the ring land which can cause the compression ring to stick in the ring groove.
The pressure seal groove will prevent gas build up below the top compression ring; these gases can cause the ring to lift from the ring groove. Unseating of the ring will result in compression losses and lower performance.
● THIS 168CC CYLINDER KIT IS THE CORRECT KIT TO BE INSTALLED ON THESE eSP+ ENGINES:
● 125CC 4V eSP+ (STD BORE X STROKE= 53.5MM x 55.5MM):
● 150/160CC 4V eSP+ (STD BORE X STROKE= 60MM x 55.5MM):
● 60MM FLAT HIGH COMPRESSION PISTON SPECIFICATIONS: (CHECK BEFORE YOU ORDER!)
SMART SHOPPER TIP:
※ BUYING MORE THAN 1 PIECE CUT THE TRANSPORT PRICE, AND YOU RECEIVE A 10% DISCOUNT ON TOP OF IT!
※ B2B:
All prices are in THB