The Black Hole Oil Drain Plug | Honda CB360 / CL360 / CJ360
The stock oil drain plug on the CB360, CL360, and CJ360 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: a drain plug 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. The Black Hole was the first part Common Motor ever designed from scratch, built specifically 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 seals with an O-ring instead of the original crush washer, so there's no soft aluminium washer to flatten and weep.
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
- O-ring seal (included) replaces the original aluminium crush washer
- Made in Houston, Texas, USA — backed by a lifetime warranty
Specifications
| Spec | Detail |
|---|
| Replaces OEM Parts | 90013-230-000, 90407-367-690, 90407-205-000 |
| Fits Models | CB360G (1974), CB360T (1975–1976), CL360K0 (1974), CL360K1 (1975), CJ360T (1976–1977) |
| Material | 4130 Cro-Moly steel billet |
| Finish | QPQ case-hardened, corrosion resistant |
| Hex Size | 22mm |
| Seal | O-ring (included) |
| Sold As | Sold Individually |
Installation
Difficulty: Beginner
Tools needed: 22mm socket or wrench (a breaker bar helps 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 breaker bar helps 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.
- 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. The CB360 holds 1.5 L / 1.6 US qt.
Oil: The factory oil grade is SAE 10W-40. We run a 15W-40 100% mineral oil with about two ounces of zinc additive per quart at every change, and recommend a fresh oil change every 1,500 miles. The CB360 uses a centrifugal oil filter rather than a paper element — clean it every other oil change, about every 3,000 miles.
Our CB360 / CL360 / CJ360 engine oil change video walks through draining the oil and swapping in the drain plug.
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 instead of soft steel, a QPQ case-hardened finish, a built-in particle magnet, a larger 22mm hex head, and an O-ring seal — backed by a lifetime warranty. Both fit the same CB360-family drain threads.
Will it fit my CJ360?
Yes — it fits the stock CB360G, CB360T, CL360, and CJ360T. If a previous owner installed a non-stock or oversize drain bolt, or the crankcase threads have been altered, this OEM-thread plug won't thread into the modified hole.
Will the Black Hole fix stripped or cross-threaded drain threads?
No. It's a direct OEM-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.
What size wrench does it take?
A 22mm socket or wrench. The larger hex is one of the upgrades — it gives a far better grip than the stock plug, which is part of why the originals round off so easily.
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Last updated: June 2026
