Valve Adjustment Wrench | Honda CT90 / CB175 / CB200
The valve adjusters on Honda CT90, CB175, CL175, SL175, CB200, and CL200 motorcycles use a small square-head tappet screw that standard wrenches cannot reach. This 3mm/4mm double box end wrench fits those square adjusters and makes valve clearance adjustments fast and accurate — no more fumbling with pliers or adjustable wrenches in tight spaces.
Why You Need This
Valve adjustment is part of the standard tune-up on every CT90 and CB175/CB200-family engine. The sequence is cam chain, valves, then ignition timing — in that order, because each step affects the next. Honda specifies this service every 1,500 miles (2,400 km). Without the correct wrench for the square-head adjusters, getting a precise clearance setting is nearly impossible. This wrench gives you clean, interference-free access to the adjuster screw while you hold the jam nut with a standard box wrench.
Also works with many Yamaha, Suzuki, and Kawasaki models that use 3mm or 4mm square-head valve adjusters.
Specifications
| Spec | Detail |
|---|
| Size | 3mm / 4mm Double Box End |
| Fits Models | CT90 (1966–1979), CB175 (1968–1973), CL175 (1968–1973), SL175 (1970–1972), CB200 (1973–1976), CL200 (1974) |
| Sold As | Sold Individually |
| Cross-Compatibility | Also fits Yamaha, Suzuki, and Kawasaki models with 3mm/4mm square-head valve adjusters |
Note: A set of feeler gauges is also required for setting valve clearance. Remove individual blades from the holder when measuring — the weight of the full gauge set changes how it feels and makes it harder to get an accurate reading.
How to Use This Wrench
Difficulty: Beginner
Tools needed: This valve adjustment wrench, feeler gauge set, 8mm box wrench (CB175/CB200) or 9mm box wrench (CT90)
- Remove spark plug(s) and tappet hole caps. Remove the stator/dynamo cover to access the rotor.
- Rotate the crankshaft counterclockwise to find top dead center on the compression stroke — put your finger over the spark plug hole and feel for pressure as the "T" mark aligns with the index mark.
- Loosen the jam nut with your box wrench, then back off the square-head adjuster screw using this wrench.
- Slide your feeler gauge between the rocker arm tip and the top of the valve stem.
- Turn the adjuster screw down until you feel consistent, light drag on the feeler gauge.
- Hold the adjuster screw in place with this wrench while tightening the jam nut — do not let the adjuster screw turn.
- Re-check the clearance after tightening. If you cannot pull the gauge out, it is too tight. If it slides freely with no drag, it is too loose.
Pro tip — the overshoot method: Use the next size up feeler gauge (0.003" instead of 0.002") and set it slightly tight. A tight 0.003" and a loose 0.002" are close enough — and erring on the loose side is always better. Tight valves can cause cam and rocker arm damage. Loose valves just make a little noise.
CB175/CB200 note: These engines use a 360-degree crankshaft — both pistons move up and down together. After adjusting the left cylinder's valves at TDC compression, rotate the engine 360 degrees to adjust the right cylinder.
Factory Valve Clearance Specs
| Model | Intake | Exhaust |
|---|
| CT90 (all years) | 0.05 ± 0.02 mm (0.002 ± 0.0008 in.) | 0.05 ± 0.02 mm (0.002 ± 0.0008 in.) |
| CB175 / CL175 / SL175 | 0.05 mm (0.002 in.) | 0.05 mm (0.002 in.) |
| CB200 / CL200 | 0.05 mm (0.002 in.) | 0.05 mm (0.002 in.) |
Our full cam chain and valve adjustment walkthrough for the Honda CB175/CB200 family — demonstrates this wrench in use on both intake and exhaust valves. We also have a dedicated CT90 valve adjustment video on our YouTube channel.
Frequently Asked Questions
Does this wrench fit Honda CB350, CB360, or CB450 models?
No. The CB350, CB360, and CB450 use a different style of valve adjuster — they have eccentric rocker arm shafts (CB350) or conventional screw-and-locknut adjusters that take standard metric wrenches. This wrench is specifically for the square-head tappet adjusters found on CT90, CB175/CL175/SL175, and CB200/CL200 engines.
Can I adjust valves without this wrench?
Technically you can try with small pliers or an adjustable wrench, but getting a precise clearance setting is extremely difficult. The square-head adjuster requires a close-fitting box wrench to hold position while you tighten the jam nut. Without it, the adjuster tends to turn as you tighten, throwing off your clearance.
How often should I adjust my valves?
Honda specifies every 1,500 miles (2,400 km) for the CB175/CB200 family and every 3,000 miles for the CT90. Valve adjustment is part of the standard tune-up along with cam chain adjustment and ignition timing — always in that order. Some owners prefer to check valves at every oil change interval for peace of mind.
What feeler gauge size do I need?
Factory spec for all supported models is 0.002" (0.05 mm) for both intake and exhaust valves. We recommend using a 0.003" gauge and setting it slightly tight — this "overshoot method" ensures you end up on the loose side, which is safer for the engine.
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Last updated: March 2026
