Sun Coast Cycle Sports offers inspected used parts for Honda's vintage CM series, the company's late-1970s and early-1980s line of entry-level cruiser and custom-styled motorcycles. The CM family includes the CM400 (1979-1981), CM450 (1982-1986), CM250 (1982-1983), and the CMX450 Rebel (1986-1987). These parallel-twin-powered bikes served as precursors to the Honda Rebel line and are recognized for their approachable size, low seat height, and classic custom styling. Every CM-series component in our inventory is reviewed by Sun Coast technicians, individually photographed, and ships from Odessa, Florida.
Vintage CM platform overview
The CM series used air-cooled SOHC parallel-twin engines with three valves per cylinder across most variants. The CM400 came in four sub-models: A (Hondamatic semi-automatic two-speed), C (Custom, 1981 only), E (Economy), and T (Touring). In 1982, the engine was bored to 447cc and renamed the CM450, available in A (automatic), C (Custom), and E (standard) trims. The CM250 (1982-1983) used a smaller 234cc parallel twin. The CMX450 Rebel (1986-1987) shared the 447cc engine in a new cruiser-oriented chassis and is the direct ancestor of the long-running Honda Rebel line.
Engine internals are broadly shared between the CM400 and the CB400T of the same era, as both use the same parallel-twin engine. Similarly, the CM450 shares its engine with the CB450SC Nighthawk. The CM400 to CM450 transition involved a bore increase, so pistons and cylinders do not interchange between the two. Transmission components differ between the manual five-speed models and the two-speed Hondamatic automatic models. The CMX450 Rebel uses the CM450 engine in a different frame with different bodywork. Frames and cosmetic components are model-specific across the CM series.
Common vintage CM failure points and replacement parts
Carburetor fouling: These 40+ year old bikes almost universally need carburetor work. The dual Keihin carburetors clog from fuel degradation, and diaphragms crack with age. Complete rebuild kits are available in the aftermarket.
Charging system: The stator and points-based ignition system (on earlier models) are common failure points. Many owners upgrade to electronic ignition for improved reliability and easier starting.
Cam chain tensioner: The SOHC parallel twin uses a cam chain and tensioner that wear with mileage, causing chain rattle and timing imprecision. Tensioner replacement is a routine service item.
Hondamatic torque converter (A models): The semi-automatic CM400A and CM450A models use a torque converter that shares its oil with the engine. Short oil change intervals (every 1,875 miles) are critical. Neglected oil changes lead to torque converter contamination and slipping.
Exhaust rust: The chrome exhaust pipes on CM models are prone to corrosion, particularly at the collector and balance tube area. Finding rust-free original exhausts is difficult; aftermarket and used replacements are the primary options.
Commonly replaced vintage CM parts
- Carburetor rebuild kits
- Stator, ignition points, and condensers
- Cam chain tensioner
- Exhaust pipes and mufflers
- Brake pads, shoes, and cables
- Fuel petcock and fuel lines
- Seats and side covers
- Chain and sprocket sets
Frequently asked questions
Q: Do CM400 and CB400T share engine parts
Yes. The CM400 and CB400T use the same 395cc SOHC parallel-twin engine. Pistons, valves, cam chain, and most internal components interchange between the two. The primary differences are in cosmetics, ergonomics, and exhaust routing. The Hondamatic CM400A uses a different transmission (two-speed automatic with torque converter) that does not interchange with the five-speed manual models.
Q: Will CM450 parts fit a CM400
The CM450 is a bored-out version of the CM400 engine (447cc vs 395cc). Pistons and cylinders are different between the two. Valve train, cam chain, transmission gears (on manual models), and many other internal components are shared. Frames are similar but not identical between the CM400 and CM450 due to minor geometry changes across model years.
Inspected by Powersports Technicians • Only One in Stock • Ships Fast from Florida
