The Black Hole Oil Drain Plug | Honda CB175 / CB200 / CB350 / CB450
The stock oil drain plug across the Honda twins is soft, and after decades of seized removals it rounds off and chews up — until one day it won't come out at all. "The Black Hole" is Common Motor's billet replacement: one upgraded drain plug that fits the whole CB175 / CB200 / CB350 / CB450 family, built to outlast the bike.
Why You Need This
If your drain plug head is rounded, burred, or fights you at every oil change, you're one stuck plug away from a much bigger job — and the soft factory plugs chew up fast, especially when someone reaches for a 12-point socket. The Black Hole was the first part Common Motor ever designed from scratch, built to fix everything wrong with the original. It's machined from 4130 Cro-Moly steel billet, case-hardened with a QPQ finish for corrosion resistance, and carries a built-in magnet that pulls metal particles out of your oil before they circulate. It keeps the original's O-ring seal (included) instead of a crush washer, and adds a drilled safety-wire hole.
Features
- Machined from 4130 Cro-Moly steel billet — far stronger than the soft factory plug
- QPQ (quench-polish-quench) case-hardened finish for corrosion resistance — not anodized or black oxide
- Built-in magnet that collects metal particles from the oil
- Larger 22mm hex head for a solid wrench grip that won't round off
- Safety-wire hole drilled through the head
- O-ring seal (included) — no crush washer needed
- Made in Houston, Texas, USA — backed by a lifetime warranty
Specifications
| Spec | Detail |
|---|
| Replaces OEM Parts | 90013-312-000, 91304-HB3-003, 91302-943-003, 91302-200-000 |
| Fits Models | CB175 / CL175 / SL175 (1968–1973), CB200 / CB200T / CL200 (1973–1976), CB350 / CL350 / SL350 (1968–1973), CB450 / CL450 (1965–1974), CB500T (1975–1976) |
| Material | 4130 Cro-Moly steel billet |
| Finish | QPQ case-hardened, corrosion resistant |
| Hex Size | 22mm |
| Thread | M33.7 x 1.5mm |
| Seal | O-ring (included) |
| Sold As | Sold Individually |
Installation
Difficulty: Beginner
Tools needed: 22mm socket or wrench (a 6-point socket and a breaker bar help free a stuck original plug)
- Run the engine for a few minutes so the oil drains warm, then position a drain pan underneath.
- Break the old plug loose — a 6-point socket and a breaker bar help if it's seized — remove it, and let the oil drain completely.
- Check that the new plug's O-ring sits level in its groove; a little grease helps hold it in place. Replace the O-ring at every oil change.
- Thread the Black Hole in by hand, then snug it with a 22mm wrench. Do not over-tighten — an overtightened plug makes your next oil change a nightmare.
- Refill with fresh oil and run the engine to check for leaks.
Oil: We run a 15W-40 100% mineral oil with a zinc additive, and recommend changing your oil every 1,500 miles. These engines use a centrifugal oil filter rather than a paper element — clean it every other oil change, about every 3,000 miles.
Our CB175 / CB200 family oil filter clean video shows this drain plug as part of the full oil change.
Frequently Asked Questions
What's the difference between the Black Hole and the standard drain plug?
The standard plug is an OEM-style replacement. The Black Hole is the upgrade: 4130 Cro-Moly billet, a QPQ case-hardened finish, a built-in particle magnet, a larger 22mm hex head, and a safety-wire hole — backed by a lifetime warranty. Both fit the same drain threads.
What's the thread size?
The engine-case drain thread is M33.7 x 1.5mm. Note that the 22mm figure is the hex (wrench) size, not the thread — the two get mixed up a lot. The Black Hole matches the factory M33.7 x 1.5mm thread.
Will the Black Hole fix stripped or cross-threaded drain threads?
No. It's a direct factory-thread replacement, not an oversize or thread-repair plug. If the threads in your crankcase are already stripped or cross-threaded, that's a thread-repair job — the plug itself can't restore damaged threads.
Do I need a crush washer with it?
No. The Black Hole seals with the included O-ring, so there's no crush washer to replace. Make sure the O-ring sits level (a dab of grease helps), thread it in, and snug it — don't over-tighten. Replace the O-ring at every oil change.
Does it fit a CB360?
No — the CB360 / CL360 / CJ360 use a different drain plug. If you have a 360, grab our CB360 Black Hole instead.
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Last updated: June 2026
