Part: "Pulsar" Series Oversize Piston Kit for Honda CB175 K3-K7 / CL175 K3-K7 Scrambler/ SL175 Motorcycles - TWO PISTONS ARE IN THE KIT
Why You Need This: After countless miles spent on the road, it may be time for an overhaul on the engine of your vintage Honda CB175 / SL175 / CL175 Scrambler. When the time comes, cylinders will need to be measured to determine if they are within the service limits of a hone and re-ring or measuring outside the factory limits, which means boring oversize. This, in turn, will require a new set of oversized pistons that match the oversize cylinder bore. In addition oversized piston rings, as well as a new wrist pin and retaining clips will need to be installed.
Finding original (obsolete) Honda oversized pistons and their matching rings for the Honda CB175 / CL175 / SL175 family of motorcycles is nearly impossible, but there is no need to worry. We here at Common Motor have manufactured our own oversized piston kits for our favorite little Honda twins and they are finally here. We are happy to introduce the "Pulsar" series oversize pistons. The "Pulsar" series pistons are based on the original ART cast aluminum pistons that came new from Honda. However, with the advances in modern manufacturing processes, we have added a number of performance improvements to the original designs.
- Each "Pulsar" piston is made from pressure cast aluminum and CNC finished machined.
- Piston skirts feature a MoS2 (molybdenum disulfide) dry film lubricant anti-friction coating to applied to the aluminum surface to reduce wear and scuffing.
- Piston crown and the top ring groove have a high temperature hard anodizaton applied to the surfaces to increase overall piston durability and thermal transfer (important in an air cooled engine) as well as preventing the top ring from micro welding (aka getting "stuck") into the ring groove.
Speaking of rings, the "Pulsar" series pistons include modern piston rings to improve sealing, ease of install and ensure long service life. Each ring set includes:
- A gas nitride coated forged steel top ring (silver). This is a hard coating on all surfaces of the ring and gives increased wear resistance and lower coefficient of friction on the cylinder walls.
- Steel phosphate coated 2nd ring (black).
- Modern gas nitirde three piece oil ring, which makes installation on to the piston and cylinder assembly as LOT easier that old style cast iron one piece oil rings.
Additionally the "Pulsar" series pistons kits also include new writs pins (gudgeon pin) and the proper "C" style retaining clips, for correct fit with minimal pin slop.
"Pulsar" series Pistons are available in the the following oversize options:
- 0.5 mm Oversize - #4308
- 1.0 mm Oversize - #4309
This "Pulsar" Series piston kit contain TWO PISTONS, one kit will rebuild one engine
Complete the rebuild with our gasket kit, cam chain, clutch rebuild kit and some three bond gasket sealer.
Installation Tip: Install piston rings with the marked side facing up toward the crown. On the 3 piece oil rings, the wavy ring goes on first and then is sandwiched by the thin rails on the top and bottom. The "C" style wrist pin clip is installed with the open end opposite from the notch in the side of the piston. Ensure that the clip seats fully in the circumference of the groove as sometimes the end of the clip can catch and not fully engage. Put the clips on the inner side of each piston (side closest to the cam chain) before placing the pistons on the connecting rods. Thus install the wrist pin from the side of each piston facing away from the cam chain. Put some rags in the engine case and cam chain hole so you do not drop the wrist pin clip in the bottom of the engine case! Check small end of the connecting rod inner diameter for wear beyond service limit. Install the pistons with the arrow facing toward the front of the engine. Make sure to lubricate the pistons and cylinders with motor oil before installation.
Cylinders must be bored oversize by an engine machine shop, and it is best to have the new pistons available to the machinist when dropping the cylinders off for work. We recommend a 0.0015" to 0.002" piston to cylinder wall clearance when over boring cylinders. Wash newly machined cylinders with hot water and dish detergent. Wipe the cylinders clean with a white cloth, when the cloth shows no dark residue the cylinders are ready for reassembly.
