Part:"Pulsar" Series Oversize Piston Kit for Honda CB550K / CB550F Motorcycles - FOUR PISTONS ARE IN THE KIT
Why You Need This: Even though the Honda CB550K / CB550F engines are quite tough machines and will deliver up miles of reliable service, wear will still take a toll on them, and sooner or later a top end engine overhaul is in order. When this time comes, the cylinders need to be measured to determine if they are within the wear service limits. If so, a de-glaze hone with re-ring is in order and back in with the stock pistons you go. However, if your engine's cylinders measure out to be outside the factory limits they will have to be bored oversize. This requires a new set of pistons that match the oversize bore, a fresh set of oversized piston rings, as well as a new wrist pin and retaining clips to be installed.
For the Honda CB550K / CB550 family of motorcycles, finding original Honda oversized pistons and their matching rings is has been tough as they are an obsolete part, but you have no reason to worry. The Common Motor Crew has stepped in to make new and better pistons that we all need to keep your vintage Honda CB550K / CB550F on the road. We are thrilled to introduce the "Pulsar" series oversize pistons. The "Pulsar" series pistons are derived from the original ART cast aluminum pistons used 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 di-sulfide) 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 installation and ensure long service life. Each ring set includes:
- The top ring (silver) is forged steel with a gas nitride coating. This is a hard coating process that permeates all surfaces of the ring, increasing wear resistance and reducing the coefficient of friction on the cylinder walls
- Steel phosphate coated 2nd ring (black).
- A three piece oil ring, which makes easy installation on the piston and into the cylinder assembly (A LOT easier than cast iron one piece oil rings). Top and bottom rails of the oil ring are also gas nitirde coated.
In addition, the "Pulsar" series pistons kits also include correct length 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 - #4310
- 1.0 mm Oversize - #4311
This "Pulsar" Series piston kit contain FOUR PISTONS, one kit will rebuild one engine
Complete the rebuild with our gasket kit, cam chain, clutch rebuild kit and some Honda 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.
The cylinders must be bored to the correct size by an engine machine shop. Pistons and cylinders should be dropped off together to the machine shop so that they can be matched when boring. Newly machined cylinders should be washed with hot water and dish detergent, using a white cloth to wipe the cylinders clean. When the cloth shows no residue the cylinders are clean and ready for reassembly.
