Honda CB175 / CL175 / SL175 Gasket Kit (Service)
The middle tier of three CB175 family gasket kits. The Service kit goes beyond the routine oil change scope (Letters A–H) and adds every paper gasket and O-ring you'll touch during a full tune-up — points cover, intake manifold (paper gaskets and O-rings together), left crankcase cover, and top cam cover — 13 gasket types in one box.
Why You Need This
A real Trail 175 tune-up — cam chain, valves, ignition timing, intake reseal — means opening half the engine's covers. Even gaskets that look fine should be replaced, because once a paper gasket has been compressed and heat-cycled it will not seat the same way twice. This kit bundles every gasket and O-ring you'll cross during that work: the routine oil-change parts plus the points cover, intake manifold paper-and-O-ring stack, left crankcase cover, and the cylinder head cover gasket that sits above the camshaft.
Honda's published service procedures call for replacing these gaskets and O-rings with new parts on reassembly. A 50-plus-year-old paper gasket is the fast path to an oil weep from a cover that was sealed yesterday.
Specifications
| Spec | Detail |
|---|
| Fits Models | CB175 K3 (1969), K4 (1970), K5 (1971), K6 (1972), K7 (1973); CL175 K3 (1969), K4 (1970), K5 (1971), K6 (1972), K7 (1973); SL175 K0 (1970), K1 (1971–1972); also fits Honda CD175 and CA175 (same engine architecture) |
| Replaces OEM Parts | 30391-216-306, 30391-216-000, 16229-235-306, 16229-235-000, 11395-302-307, 11395-302-010, 12391-354-306, 12391-216-000, 12391-354-000, 91301-216-000, 91305-426-003, 91305-216-000, 91310-MG7-003, 91305-634-961, 91309-700-000, 91309-302-000, 91304-HB3-003, 91302-200-000, 91302-943-003, 15219-302-000, 11691-354-306, 11691-216-000, 11691-354-000, 11394-302-306, 11394-302-010 |
| Sold As | Kit (13 gasket types, 17 individual pieces — Letters A through M) |
Note — this kit does NOT fit the 1968 CL175 K1 "sloper" engine. The 1968 CL175 K1 used a different engine based on the CB160 platform. Its gaskets are not compatible with the K3+ CB175/CL175/SL175 family this kit is built for.
Note — intake manifold rubber boots are not sold separately. Letters J and K seal the carb-to-manifold and manifold-to-engine joints (with both O-rings and paper gaskets, unlike the CB200 family which uses paper only). But the rubber boot itself between the carburetor and intake flange isn't in CMC's catalog — if your boot is cracked, you'll need to source it used or new-old-stock.
Note — valve stem seals are NOT in this kit. If you're pulling valves for guide work or replacement, you'll need the Overhaul Kit (#4175) — only the Overhaul tier carries the valve stem seals (Letters X + Y).
Note — this kit covers gaskets and O-rings only. It does not include the cam chain, cam chain tensioner, valves, valve springs, piston, rings, or any wear part. We sell those separately: CB175 cam chain, CB175 carburetor rebuild kit.
Model-Specific Notes
- CD175 and CA175 share the same engine architecture and gasket set as the CB175/CL175/SL175. Caleb confirmed cross-fit on real customer questions.
- 1968 CL175 K1 "sloper" — does NOT fit. CB160 platform engine, different gaskets.
- Single set of points — the CB175/CL175/SL175 (like the CB200) is a 360° crankshaft engine where both pistons move together. That means ONE set of ignition points serves both cylinders. If you've worked on a CB350/CB360 (180° crankshaft) before and are looking for a "right side points cover," there isn't one on the 175 — Letter I is the single points cover gasket.
- Two points manufacturers — Nippon Denso and Hitachi were both used on the 175 family. Different visual designs (larger rocker vs smaller eccentric-adjustment design). Either is correct for the gasket fitment in this kit.
What's in the Kit
This Service kit includes everything from the Oil Change kit (Letters A–H) plus 5 additional gaskets and O-rings (I, J, K, L, M) for the points cover, intake manifold (both O-rings and paper gaskets), left crankcase cover, and top cam cover.
Honda CB175 / CL175 / SL175 Gasket Kit Comparison
| Kit | Letter | Gasket | Qty |
|---|
#4176
Oil Change Gasket Kit
(Includes Gaskets A–H) | A | Stator Rotor Cover Bolt O-Rings | 3 |
|---|
| B | Oil Rotor Cover O-Ring | 1 |
| C | Oil Filter Cover O-Ring (Small) | 1 |
| D | Oil Filter Cover O-Ring (Large) | 1 |
| E | Oil Drain Plug O-Ring | 1 |
| F | Oil Pump Gasket | 1 |
| G | Stator Rotor Cover Gasket | 1 |
| H | Right Crankcase Cover Gasket | 1 |
#4177
Service Gasket Kit
(Includes Gaskets A–M) | I | Points Cover Gasket | 1 |
|---|
| J | Intake Manifold O-Rings | 2 |
| K | Intake Manifold Gaskets | 2 |
| L | Left Crankcase Cover Gasket | 1 |
| M | Top Cam Cover Gasket | 1 |
#4175
Overhaul Gasket Kit
(Includes Gaskets A–Y) | N | Cylinder Base Gasket | 1 |
|---|
| O | Head Gasket | 1 |
| P | Exhaust Gaskets (copper) | 2 |
| Q | Camshaft End Cover | 2 |
| R | Dipstick O-Ring | 1 |
| S | Clutch Lifter Adjuster O-Ring | 1 |
| T | Valve Cover O-Ring | 4 |
| U | Exhaust Guide to Head O-Rings | 2 |
| V | Tensioner Bolt O-Ring | 1 |
| W | Cylinder Head Dowel Oil Passage O-Ring | 2 |
| X | Exhaust Valve Stem Seal Upper | 2 |
| Y | Exhaust Valve Stem Seal Lower | 2 |
Installation
Difficulty: Intermediate
Tools needed: Standard hand tools, 9mm wrench for the valve adjuster jam nut, feeler gauge set (0.002–0.016 in range), single-edge razor blade, acetone, anti-seize lubricant. A timing/test light helps for the ignition timing step.
The 175/200 family tune-up sequence is cam chain → valves → ignition timing. Do them in that order, because adjusting one shifts the next.
- Drain the oil and clean the centrifugal oil filter rotor on the right side (Letters A–H scope). Refill at the end with 1.5 L / 1.6 US qt SAE 10W-40 100% mineral oil plus 2 oz zinc additive per quart.
- Cam chain tension. Pull the top cam cover off (Letter M sits between the cover and the cylinder head). Adjust the cam chain following the procedure in our walk-through video below. On reassembly, fit the new Letter M gasket; torque the cylinder head cover cap nuts to 160–210 kg-cm (11.6–15.2 ft-lbs) in a diagonal pattern,.
- Valve adjustment. Find TDC on compression by feeling air at the spark plug hole as you rotate the crank — the rotor's T mark should align with the index mark. Adjust both valves on the left cylinder first (the reference side), then rotate 360° for the right cylinder. Spec is 0.05 mm (0.002 in) on both intake and exhaust. Overshoot to 0.003 in (0.08 mm) and loosen back — thermal expansion is more forgiving when slightly loose. Use a 9mm wrench on the jam nut (or our Valve Adjustment Wrench).
- Ignition timing (Letter I). Remove the points cover (two flat-head screws — consider swapping these for an Allen-head set during reassembly). Set the point gap to 0.012–0.016 in (0.3–0.4 mm) using a feeler gauge. Then set static timing so the points just begin to open as the rotor's F mark aligns with the index mark. After timing is set, apply a small dab of grease on the points cam where the rubbing block contacts. Reassemble with the new Letter I Points Cover Gasket. Walk-through video for points work: Setting the Ignition Timing on the Honda CB175 / CB200 Family.
- Intake manifold and carburetor (Letters J + K). Pull the carburetor and intake manifold for inspection. The CB175 family uses BOTH a paper gasket AND an O-ring at the carb-to-manifold and manifold-to-engine interfaces — the kit gives you two of each. Clean both flanges with a razor and acetone before fitting the new gaskets. A light film of grease on the paper gaskets keeps them in place during reassembly. Tighten the manifold mounting hardware to manual spec.
- Left crankcase cover (Letter L). If you're servicing the gearshift mechanism, the AC generator stator, or chasing a left-side oil weep, drop the cover., disconnect the neutral lead wire harness and remove the dynamo cord clamp from the stator before pulling the cover. Replace the Letter L gasket and reseal carefully — the cover houses the stator, so don't over-tighten.
- Idle and air screw. After the engine is back together and warm, set idle to 1,200 RPM.
Installation Tip: Clean all surfaces with a razor blade and acetone. Lightly grease new paper gaskets when installing — it prevents sticking and lets the joint come apart cleanly next time without ripping the gasket. Use anti-seize on cover bolt threads.
Brenden walks through the cam chain and valve adjustment procedure for the CB175 / CB200 family end to end — the T-mark alignment, the 9mm wrench overshoot technique, the cam chain adjuster between the exhaust pipes, and the 360° rotate for the second cylinder. The same procedure that calls for Letters M (top cam cover gasket) on reassembly.
Frequently Asked Questions
I have a left-side oil weep on my CB175 / CL175 — will this kit fix it?
Probably yes. The Service Kit's Letter L is the Left Crankcase Cover Gasket — the most common source of a left-side oil leak on these bikes (the cover houses the AC generator stator and gearshift mechanism). Drop the cover per the procedure in the CB175 Service Manual, scrape the old gasket cleanly, install the fresh Letter L, and reseal. If the leak is at a different location (right side, cam cover, intake), other letters in this kit will likely fix it.
What's the difference between #4176 Oil Change, #4177 Service, and #4175 Overhaul?
Three tiers, cumulative letter scope:
- #4176 Oil Change (A–H): Eight gaskets and O-rings for a routine oil and filter change.
- #4177 Service (A–M): A–H plus five more (I, J, K, L, M) for a full tune-up: points cover, intake manifold (paper gaskets AND O-rings), left crankcase cover, and top cam cover.
- #4175 Overhaul (A–Y): Everything in Service plus 12 more (N–Y): head gasket, cylinder base, exhaust gaskets, camshaft end covers, valve stem seals (upper and lower), and the gaskets you only touch with the head off.
Are valve stem seals in this kit?
No. The Service kit covers the valve cover/inspection cover O-rings on the top of the head, but the exhaust valve stem seals themselves (the seals between valve guide and valve stem) live in the Overhaul Kit (#4175), Letters X and Y. If you're pulling valves for guide work or replacement, step up to Overhaul.
How is this different from the CB200 Service kit?
The intake manifold scope. The CB175 family uses BOTH paper gaskets AND O-rings at the carb-to-manifold interface (Letters J + K in this kit, two of each). The CB200 family uses paper gaskets only at the same joint — no O-rings — because Honda redesigned the intake flange between the two engines. If you have a CB175 you're getting the more complete seal package. The two kits are NOT interchangeable.
Does this kit fit my Honda CD175 or CA175?
Yes. The CD175 and CA175 share the same engine architecture as the CB175 / CL175 / SL175. The same gaskets fit. We've shipped this kit to multiple CD175 and CA175 customers on Caleb's recommendation.
Does this kit fit my 1968 CL175 K1?
No. The 1968 CL175 K1 used the "sloper" engine based on the CB160 platform, with different gaskets. This kit covers 1969 K3 and later only. If you have a 1968 K1 sloper, you'll need to source CB160-platform gaskets separately.
I'm coming from a CB350 — why is there only one set of points in this kit?
The CB175 / CB200 family is a 360° crankshaft engine (both pistons move together) which uses a single set of ignition points serving both cylinders. The CB350 / CB360 family is a 180° crankshaft (pistons opposed) and needs separate left and right point sets. If you're looking for a "right side points cover" on a 175, there isn't one — Letter I is the single points cover gasket.
How often should I do a full Service?
CMC's recommendation is every 1,500 miles for a full tune-up (oil change + cam chain + valves + ignition timing). Honda's factory schedule is longer, but these little air-cooled twins drift on the points and valves faster than the factory cadence suggests. Pair every service with an oil change using SAE 10W-40 100% mineral and 2 oz of zinc additive per quart. Avoid the semi-synthetic diesel oils (Shell Rotella T4, Chevron Delo 400, Mobil Delvac 1300 — reformulated to semi-synthetic in late 2023) — the friction modifiers cause the wet clutch to slip.
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Last updated: May 2026
