Gasket Kit (Service) | Honda CL450 / CB450 / CB500T

Description

Honda CL450 / CB450 / CB500T Gasket Kit (Service)

Valve covers are off. Points cover is off. Carbs are coming off. The CB450 family is a DOHC parallel twin — service intervals come up fast, and every cover that moves takes a gasket with it. This is the middle tier of three CB450 family gasket kits, with all 10 gasket types (16 pieces) for routine valve adjustment, ignition timing, intake reseal, and left-side service work.

Why You Need This

The Service kit is the middle tier between Oil Change (4019, A–F) and Overhaul (4035, A–V). Choose this kit for work that goes beyond an oil change but stops short of pulling the cylinders — valve adjustment (Letter I, four valve cover gaskets disturbed), ignition timing service (Letter H, points cover), carb reseal (Letter G, intake manifold gaskets), or stator/shifter work (Letter J, left crankcase cover). Letters A–F carry over from the Oil Change tier so the kit also handles routine right-side oil and filter clean work.

The CB450 valve clearance comes up at 1,500 miles — CMC’s recommended interval — and every adjustment removes the four small valve adjuster covers. Reusing the old gaskets is the fast path to a slow weep down the cooling fins after the first heat cycle. This kit replaces every paper and rubber surface disturbed during a routine Service.

Specifications

Note — the kit ships with 4 valve cover gaskets (Letter I), not 2. The CB450 family has two main valve covers (one each side), but each side also has a metal breather baffle that needs its own gasket. So a complete reseal uses 4 gaskets total. Some early K0 engines may only need 3 if a baffle is missing on one side — the spare goes in your toolbox for next time.

Note — this kit covers Service-tier work only. If you’re pulling the cylinder head, head gasket, valve stem seals, or splitting the cases, you need the 4035 Overhaul Gasket Kit (A–V). The Service kit (4064) does not include the head gasket, valve stem seals, or cylinder base gasket.

Model-Specific Notes

• CB450 K0 “Black Bomber” (1965–1967) — gaskets fit identically across all K-suffix CB450 years. The K0’s wiring is different from later models, but the gasket kit is the same.
• CL450 Scrambler = K0 (1967) through K6 (1974). CL450 K5 was produced and sold across both 1972 and 1973 model years — either year is the K5.
• CB500T (1975–1976) is the bored-out evolution of the CB450 DOHC twin (498cc vs 444cc). Same gasket footprint, same kit.
• Does not fit CB500K or CB550K/F. Those are inline-four-cylinder bikes, entirely different engine architecture. “CB500” alone is ambiguous — check whether your bike is a CB500T (twin, this kit fits) or CB500K (four, this kit does NOT fit).
• Does not fit CB350 / CB360 / CB175 / CB200 / CB550K / CB550F / CB750. Each is a different engine architecture with different gasket sizes.

What’s in the Kit

This Service kit includes everything from the Oil Change kit (Letters A–F) plus 4 more gasket types (G–J) that get touched during deeper service: intake manifolds, points cover, the four valve adjuster covers, and the left crankcase cover.

Installation

Difficulty: Intermediate

Tools needed: JIS Phillips driver (or upgrade to Upper Allen Bolt Kit for valve covers + points cover + cam end covers), 0.004″ feeler gauge (for the overshoot valve-adjustment method), anti-seize, light white grease for sealing surfaces, single-edge razor blade, acetone.

1. Valve adjustment (Letter I, four covers). CMC recommends a 0.08 mm (0.003 in) valve clearance — looser than the factory 0.03 mm / 0.0012 in spec to prevent cam-lobe wear at the tight setting. Use the overshoot method: set with a 0.004″ feeler, then back off — “tight 4 = loose 3.” Remove the four valve adjuster covers and replace each gasket on reassembly.
2. Cam chain adjustment. Cam chain comes up alongside valve adjustment at the 1,500 mile service. With the stator cover off (Letter F), bring the engine to 90° past TDC compression on the left cylinder using the custom index mark, then loosen the tensioner adjuster and re-tighten.
3. Ignition timing service (Letter H). Pull the points cover — clean and inspect the contact faces, set the gap, and time both cylinders against the “LF” mark for the left cylinder and the “F” mark for the right. Replace the points cover gasket on reassembly.
4. Intake manifold reseal (Letter G). To replace the two paper intake manifold gaskets, remove the carbs as an assembly. Reseal with new gaskets and torque the manifold bolts evenly — an air leak at the manifold causes lean idle and erratic carb behavior.
5. Left crankcase cover work (Letter J). The left cover houses the generator and starting clutch. Drain oil before removing — oil sits behind this cover. Disconnect the neutral lead and stator wiring before pulling the cover. Replace the gasket on reassembly.
6. Right crankcase / oil filter (Letters A–F). If you’re also cleaning the centrifugal oil filter, the right crankcase cover comes off — remove the kick starter, footrest, and the oil filter cap. The CB450 family has a separate oil filter access on the right cover — unlike the CB360, you don’t need the full side cover off just for routine oil filter clean (Letter D handles the filter cover O-ring on its own).
7. Clean every surface. Use a single-edge razor and acetone. Scrape every trace of old gasket material or silicone. Apply a thin coat of white grease to the sealing surface of each gasket on reassembly — this lets you pull the covers next time without ripping the gasket. Do NOT use RTV silicone — it sheds debris into the oil galleries on these wet-clutch engines.
8. Refill oil if drained. 2.8 L / 2.9 US qt of SAE 10W-40 100% mineral oil + 2 oz of Zinc ZDDP additive per quart. Avoid semi-synthetic oils — modern reformulated diesel oils (Shell Rotella T4, Chevron Delo 400, Mobil Delvac 1300, all reformulated to semi-synthetic in late 2023) cause clutch slip on CB450 wet clutches.

Installation Tip: The rubberized gasket material in this kit will hold up to three or four side-cover removals before replacement — if you store the bike well between rides and keep the cover bolts at moderate torque, you’ll get multiple service cycles from one set.