The Honda, Piaggio, Vespa and Yamaha Scooters repair manual by Haynes, covers 50cc to 250cc scooters with automatic transmissions, including:

HONDA
CHF50 Metropolitan 2002-2005 | NB50 Aero 1985-1987 | NPS50 Ruckus 2003-2005 | NQ50 Spree 1984-1987 | SA50 Elite 1988-2001 | SB50 Elite 1988-2001 | SE50 Elite 1987 | NH80 Aero 1985 | CH80 Elite 1985-1987 | CH150 Elite 1985-1987 | CH250 Elite 1985-1988 | CH250 Elite 1989-1990 | CN250 Helix 1986-2001 | CN250 Helix 2004-on | NS250 Reflex 2001-on PIAGGIO
FLY150 2005 | BV200 2002-on VESPA
LX50 2005 | LX150 2005 | GT200 2004-on YAMAHA
CA50 Riva 1985-1986 | CE50, CG50 Jog 1986-1987 | CW50 Zuma, Zuma II 1997-2000 | CW50 Zuma 1989-1990 | CY50 Riva, Riva Jog 1992-on | YJ50 Vino 2001-2004 | YW50 Zuma 2002-2004 | CV80 Zuma 1984-1987 | XC125 Riva 1985-2001 | YJ125 Vino 2004 | XC200 Riva 1987-1991

Book Excerpt: Scooters: Automatic Transmission 50cc to 250cc - Honda, Piaggio, Vespa, Yamaha TWO-STROKE ENGINES

PISTON RINGS-INSPECTION AND INSTALLATION

1. New piston rings should be fitted whenever an engine is being overhauled. It is important that you get new rings of the correct size for your piston so ensure that any information related to piston size, including rebore size, and size coding is available when purchasing new parts.
2. Before fitting the new rings onto the piston, the ring gaps must be checked. Insert the top ring into the bottom of the cylinder bore and square it up by pushing it in with the top of the piston. The ring should be about 15 to 20 mm from the bottom edge of the cylinder. To measure the end gap, slip a feeler gauge between the ends of the ring and compare the measurement to the specification in the Data section at the end of this manual (see illustration).
3. If the gap is larger or smaller than specified, check that you have the correct rings before proceeding. If the gap is larger than specified it is likely the cylinder bore is worn. If the gap is too small the ring ends may come in contact with each other during engine operation, causing serious damage.
4. Repeat the procedure for the other ring.
5. Once the ring end gaps have been checked, the rings can be installed on the piston. First, identify the ring locating pin in each piston ring groove - the ring must be positioned so that the pin is in between the ends of the ring (see illustration 7.12).
6. If the piston has an expander fitted behind the lower ring, fit that first, ensuring that the ends of the expander do not overlap the ring locating pin (see illustration 8.8)
7. The upper surface of each ring should be marked at one end; make sure you fit the rings the right way up. Install the lower ring first. Do not expand the ring any more than is necessary to slide it into place and check that the locating pin is between the ends of the ring (see illustration).
8. Install the top ring. Always ensure the ring end gaps are positioned each side of the locating pins before fitting the piston into the cylinder.

FUEL AND EXHAUST SYSTEMS

SLIDE CARBURETOR | OVERHAUL WARNING: refer to the precautions given in Section 1 before starting work. NOTE: The carburetor design differs for two-stroke and four-stroke engines. Two-stroke engines use a slide carburetor, whereas four-stroke engines generally use a constant vacuum (CV) type - refer to the specifications in the Data section at the end of this manual to ensure that you follow the correct procedure either in this Section or Section 9. DISASSEMBLY

1. Remove the carburetor (see Section 7). Take care when removing components to note their exact locations and any springs or O-rings that may e fitted (see illustration).
2. Where fitted, remove the cover of the automatic choke unit , then remove the clamp securing the unit in the carburetor (see illustrations). Withdraw the choke unit, noting how it fits (see illustration).
3. To remove the throttle side assembly from the cable if the top cover and slide assembly have already been removed from the carburetor, first compress the slide spring. Either slot the cable end up through the side of the slide and detach the slide, or slot the cable end out of it's recess and through the hole in the bottom of the slide (see illustration).
4. On some carburetors, the needle is retained by a spring clip - remove the clip, noting how it fits (see illustration). Lift the needle out of the slide.
5. Remove the spring and, when fitted, the spring seat from the cable, then pull the carburetor top cover off the cable (see illustration).

The Haynes 10452 repair manual provides the right level of technical DIY background and instruction to help you do the service and repair work on your Honda, Piaggio, Vespa and Yamaha scooter.

Subject: Automatic Transmission 50 to 250cc Honda, Piaggio, Vespa, Yamaha scooter service, maintenance, and repair procedures. ISBN-10: 1563926024 | ISBN-13: 9781563926020 | Haynes 10452