Feeler Gauge Set | 0.002 in. to 0.025 in.
It looks like a pocket knife and it is the first precision measuring tool most vintage Honda owners should buy. Every blade in the stack is a strip of metal held to an exact thickness, and setting a gap on these bikes comes down to fitting the right one into it.
Why You Need This
Valve clearance, contact point gap and piston ring end gap are all set by feel against a known thickness. There is no way to do any of them properly by eye, and a valve set too tight is the one that breaks parts.
Blades run from 0.002 in. to 0.025 in. in 0.001 in. steps, and each one is marked in both inches and millimetres. That matters more than it sounds: American tools are graduated in thousandths while the factory manuals publish both, so a blade carrying both numbers saves you converting in your head over a warm engine.
Specifications
| Spec | Detail |
|---|
| Range | 0.002 in. (0.05 mm) to 0.025 in. (0.63 mm) |
| Increment | 0.001 in., starting at 0.002 in. |
| Markings | Inches and millimetres, on every blade |
| Fits Models | CT90 / Trail 90, CB100, CL100, CB125, CL125, CB175, CL175, SL175, CB200, CL200, CB350, CL350, SL350, CB350F, CB360, CL360, CJ360, CB400F, CB450, CL450, CB500K, CB500T, CB550K, CB550F, CB750K, CB750F, CB750A |
| Sold As | Sold Individually |
Which Blade for Which Job
Most of the standard tune-up measurements land inside this set's range. Valve clearance varies by engine family, so check yours before you reach for a blade.
Point gap is not plug gap. Contact points run 0.012–0.016 in. Spark plugs run 0.024–0.028 in., so only the very bottom of the plug range falls inside this set. Contact point gap is the ignition measurement this set covers.
Piston ring end gap is the other job in range: 0.006–0.016 in. on the CB175 family, 0.006–0.014 in. on the CB200, 0.008–0.016 in. on the CB350, 0.012–0.020 in. on the CB450, and 0.006–0.014 in. on the CB500K and CB550 top ring.
There is a fourth job the tool is good for — lay a straight edge across the cylinder head and try to slide a blade underneath it to check the deck for flatness.
How to Use It
Difficulty: Beginner
- Find the blade for your spec. Work with that one blade where you can — swinging the whole set around changes what you feel.
- Slide it into the gap. Correct is a slight drag as you pull it back out, not a slip fit and not a fight.
- Check yourself with the next size up. If that one also goes in, the gap is too wide.
The trick we use: rather than chasing a perfect slip fit on the exact spec, take the next blade up and set it snug. A tight 0.003 in. is close enough to a loose 0.002 in., and it errs in the safe direction — a valve that ends up slightly loose just makes noise, while one that ends up tight can damage the camshaft or rocker arms.
Frequently Asked Questions
How much drag should I feel?
Enough to notice, not enough to bend the blade. It should slide in without forcing and come back out with light resistance. If you are unsure, try the next size up — when that one stops fitting, the one below it is your number.
Which blade do I need for a valve adjustment?
Depends on the engine. Most of the family runs 0.002 in. intake, with exhaust anywhere from 0.002 in. to 0.004 in. — see the table above. The CB350 exhaust at 0.004 in. is the one people get wrong, because its closest siblings, the CB360 and CB550, are tighter by only a thousandth.
Can I use this for spark plug gap?
Only at the very bottom of the range. Plug gaps run 0.024–0.028 in. and climb higher on some models, so most of that range sits past this set's top blade. Contact point gap is the ignition job this set does cover.
Why are there two numbers on each blade?
Inches and millimetres. The factory manuals publish specs in both, so whichever unit your manual page happens to use, the blade already says it.
Do I need anything else to adjust valves?
A wrench for the lock nut and something to turn the adjuster, and the adjuster differs by model. The CT90, CB175 and CB200 use a square-head adjuster that takes a dedicated wrench. The CB360 and CB550 use a slotted screw you hold with a flathead screwdriver.
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Last updated: August 2026
