DROWsports LS Honda Grom 4 Valve 181cc Performance Cylinder Kit Gen 2

DROWsports LS 4v 181cc Performance Cylinder Kit for the Honda Grom/MSX125 and Honda Monkey was designed specifically for the KOSO Grom 4v Head. We wanted to offer an affordable upgrade for the KOSO 4 Valve Head. Taking features from the 170cc piston like; lightweight piston, strutted design piston, radius edge dome etc and applied it to our kit.  We love everything about the 61mm (170cc) KOSO but we wanted a little more displacement. 

Piston Features

• Forged Piston
• The 4 valve piston comes forged, which is one of the best options for performance and reliability. Forged pistons compared to cast pistons are much stronger and more reliable due to their manufacturing process. The forging process gives it stronger structural integrity over cast pistons. Forged has a smooth and consistent grain structure due to the heat and pressing process. 
• Lightweight
• (Not all forged piston are the same) Compared to KOSO 61mm 4 valve pistons, our 63mm piston only weights 10g more and the complete piston with rings and wrist pin only weights 8.5g more.  Having a lightweight and durable piston will help achieve more power and less strain.
• CNC Machined
• Once these are finished being forged, they are precision CNC machined. Machining it versus pouring metal into a cast allows the piston to have higher tolerances. This is a more expensive process but provides the highest performance option available. For this reason alone, it allows the best seal with the piston rings inside the cylinder.
• Strutted Piston Skirt
• The piston skirt utilizes a strutted design over a full round design. Having a strutted design not only reduces the weight but provides key points that can be machined to increase overall piston strength where the rods connect. This characteristic shaves off undesired weight and can be designed to help keep piston structure sturdy. This also helps with less friction due to reduced amounts of material against the sidewall of the cylinder.
• Machined Radius Edge
• Each edge on the crown has been machined with a radius edge to eliminate possible hot spots which yield better flame travel. This will prevent damage to the piston in one particular area.
• Wrist Pin Broaches & Double Pin Oiler
• Every performance piston requires proper lubrication which is commonly forgotten about once it comes down to the actual piston. Our design includes specialized oiler grooves inside the wrist pin location. The oil enters the grooves through the broached machined ports. The broaches are machined precisely to allow the proper amount of oil in for lubrication. It helps with preventing piston pin wear and seizing by keeping the entire pin oiled.
• Frictionless Coating
• Each piston comes with a specialized coating on the skirt edges that reduces piston slap and is made to be frictionless. This allows the piston to move even more freely in the cylinder. This coating reduces scuffing and provides back-up lubrication and works well with engines with longer rods and Nickasil cylinders.
• V-Shaped Accumulator Groove
• The V-Shaped groove that sits between the first and second ring was machined with an intentional purpose of relieving the top ring by adding volume between them. What it does is accumulates residual gasses from the combustion chamber. This will help prevent premature wear on the rings and provides an overall improved ring seal.

Cylinder Features

• Cylinder Performance
• DROWsports 63mm Big Bore Cylinders are all machined and specially designed for performance and reliability. Since these cylinders are paired with such a high-performance cylinder and cylinder head, we had to make sure it lasts!  This cylinder is similar to the KOSO 170cc cylinder except we've expanded on it to create an even more durable product.
• Ceramic Coated Cylinder
• The ceramic cylinder was a clear choice for heat dissipation and reliability. This type of cylinder creates a stronger exterior surface while efficiently alleviating the heat. 
• Electroplated Nikasil Walls
• We've combined this with another unique coating for the ultimate cylinder performance. The inside wall is electroplated with Nikasil. Silicone Carbide is an extremely hard ceramic compound that is dissolved and electroplated onto the cylinder walls using Nickel. This process makes the cylinder walls even more durable and allows the engine tolerances to be much tighter. Tighter tolerances mean better performance capabilities.

Includes:

• 4 Valve 63mm Forged Piston
• 181cc Ceramic Cylinder
• Piston Rings
• Piston Pin
• Piston Clips
• Head Gasket
• Base Gasket