16102-ZW2-F01 Honda CARBURETOR ASSY. (#2) (Honda Code 7552250).

Remarks
Output and torque represent performance of run-in engine operating under the standard ambient conditions and accessories specified below. Structure And Operation
Exploded View
Cylinder Head and Cylinder Head Gasket
Cylinder head
* The cylinder head has swirl chambers each with a combustion jet that directs the flow of combustion gas from the swirl chamber to the main combustion chamber.* The combustion jet is held against rotation by a tablet.* The cylinder head is cooled by coolant flowing through the water jackets formed in it. Water directors are installed at the bottom of the cylinder head to direct coolant flow.* The intake ports and the exhaust ports are arranged alternately on the right side of the cylinder head (counter-flow type)* The cylinder head bolts must be tightened according to the specified procedure.Cylinder head gasket
* Select and use a cylinder head gasket of a thickness that can accommodate the piston projection.* The size (thickness) class of the gasket can be identified by the shape of the notches cut on the edge of each gasket.Valve Mechanism and Timing Chain
Valve Mechanism
* The camshaft is driven by the timing chain. Camshaft journals are rotatably held against the cylinder head by camshaft caps.* A lifter shim is installed between the camshaft and each valve lifter. Valve clearance is adjusted by changing the thickness of the shim.* The valve springs are unequally pitched springs, each having a paint mark on one end to indicate the top when it is installed.Timing Chain
* The timing chain is an endless chain with 98 links that connects the cam sprocket and the idler sprocket.* The timing chain has mark link plates at two locations that indicate the position at which the crankshaft and the camshaft should take when the chain is installed. There are two plates at the first location and one plate at the second location. The first location (two-mark-link location) must be aligned with the mating mark " O " on the cam sprocket and the second location (one-mark-link location) must be aligned with the mating mark " O " on the idler sprocket.* The guide plate has an oil jet that sprays engine oil on the timing chain through the injection hole.* The tensioner gives tension to the timing chain. The tensioner has a plunger with a built-in spring.* When the tensioner is installed in position, the plunger pushes the tension lever and the tension lever, in turn; pushes the chain. The timing chain is tensioned automatically by a force determined by the tension of the plunger spring.* After the timing chain is adequately tensioned, the plunger is locked in place by a cam provided in the tensioner, which prevents accidental deflection of the timing chain while the engine is running. Do not crank the engine in the reverse direction after installing the tensioner, as this will apply undue forces to the plunger and may cause such undesirable consequences as cam being over ridden by the plunger.Timing Gears
* Each timing gear has mating mark(s) "1" or "5" on the side of its tooth (teeth) to ensure that it is engaged correctly with another gear during installation. The injection pump gear, however, has a mating mark on the tip of one of its teeth so that alignment of the mark with the mating marks on the flange plate and front plate can be checked from the side of the injection pump.Idler Gear
* The idler gear is pressed fitted into the idler sprocket, which drives the timing chain, and rotates on the idler shaft.* The idler shaft is anchored to the crankcase using the idler washer and bolt. The idler sprocket is fitted with the idler bushing, which is lubricated by engine oil supplied through the oil holes drilled in the idler shaft.Connecting Rods
* The "O" mark is a front mark, which should face in the same direction as the front mark on the piston when the connecting rod and piston are assembled.* The color mark indicates the diameter class of the big end.Piston and Piston Rings
* The head of the piston is provided with a front mark that indicates the direction in which the piston is inserted into the crankcase.* The piston rings are fitted onto the piston with each other's gaps staggered.Flywheel
* Tooth edges on one side of the ring gear are chamfered for easier engagement with the starter pinion.Crankcase, Crankshaft and Main Bearings
Crankcase
* The crankcase is a bi-block type consisting of an upper crankcase and a lower crankcase that are assembled to grip the crankshaft in between.* The upper crankcase has cylinder whose surfaces are machined or direct contact with sliding pistons. The walls of the cylinders have water jackets for cooling the cylinders.* The main cap bolts that hold the upper crankcase and the lower crankcase together must be tightened according to the specified procedure.* The upper crankcase is provided with piston size marks based on which position installed must be selected.Crankshaft
* The crankshaft has two sets of color marks. Color marks A indicate the outside diameter of the journals (at five places), and color marks B indicate the outside diameter of the pins (at four places).Main Bearing
* Each upper main bearing has an oil hole, which provides a passage for engine oil to the corresponding crankshaft journal.* Main bearings of different thickness are available so that most appropriate ones can be selected to ensure proper clearance between them and journals. Bearing thickness classes are identified by color marks (black, blue and yellow) painted on the sides of the bearings.* All the upper and lower bearings are identical except for the No. 3 upper bearing and the No. 3 lower bearing. The No. 3 upper bearing can be distinguished from the No. 3 lower bearing as it has an oil hole.Thrust Plates
* Two upper and lower thrust plate pairs are installed on both sides of the upper and lower main bearings at the rear most journal of the crankshaft.* The thrust plates must be of a thickness that corresponds to the end play of the crankshaft. Each thrust