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. We set the valves every 1,500 miles (2,400 km) as part of the standard tune-up. 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 (19661979), CB175 (19681973), CL175 (19681973), SL175 (19701972), CB200 (19731976), 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
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?
We do it every 1,500 miles (2,400 km) on the CB175/CB200 family as part of the standard tune-up. Honda's own figure for the CT90 is every 3,000 miles. 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
