“520” identifies chain pitch and roller width; it does not tell you strength, seal type, or whether the chain is suitable for your motorcycle. A premium sealed 520 chain and a lightweight non-sealed 520 race chain are different tools.
Sealed versus non-sealed
| Sealed 520 | Non-sealed 520 | |
|---|---|---|
| Internal lubrication | Retained by O/X-type seals | Relies heavily on external maintenance |
| Drag | Slightly higher | Potentially lower when clean and lubricated |
| Service life | Generally longer | Usually shorter in comparable real-world use |
| Maintenance | Regular cleaning, inspection, and seal-safe lubrication | Frequent cleaning and lubrication |
| Best use | Street/track and endurance-oriented builds | Specific lightweight race applications within published limits |
Why a sealed chain is our default
For a motorcycle that sees road miles, weather, multiple track weekends, or imperfect maintenance windows, a quality sealed chain offers the better ownership equation. The small theoretical drag advantage of a non-sealed chain is rarely more important than consistent condition and longer service life.
When a non-sealed race chain makes sense
DID describes the 520 ERT3 as a non-sealed chain aimed heavily at motocross and 250-class racing, with a published maximum of 450cc. That limit is the important part. Its low mass does not make it a universal supersport or superbike chain. Use it only where the chain maker approves the displacement, output, and discipline.
The ERVT alternative
A narrow sealed 520 such as the ERVT is attractive for lightweight and middleweight performance applications because it combines internal lubrication with a compact package. Fitment and power limits still matter, as do the chosen sprockets and master-link method.
Do not convert based on pitch alone
A 520 conversion changes the chain and both sprockets. The set must be engineered for the motorcycle's output and use. On a high-torque machine, a 525 or 530 system may offer the durability and safety margin the manufacturer intended. Reduced weight is not useful if adjustment moves constantly or components wear early.
Rivet master link versus clip
For high-performance road and track motorcycles, a correctly installed rivet link is the common choice. Use the exact link specified for the chain model, a suitable tool, and the manufacturer's flare and side-plate dimensions. Too little flare can allow separation; too much can bind or damage the pin.
Track inspection
- Check slack at the service-manual measurement point and with the motorcycle in the specified condition.
- Rotate the wheel and inspect the tightest section.
- Look for tight links, damaged seals, rust, hooked sprocket teeth, unusual noise, and uneven adjustment.
- Confirm axle torque and adjuster alignment.
- Keep lubricant away from the tire and brake.
- Replace chain and worn sprockets as a system.
Verdict: choose a premium sealed 520 for most street/track and middleweight builds. Reserve a non-sealed race chain for a documented application where its output limit, maintenance burden, and shorter life are acceptable.
Related product
DID 520 ERVT Chain
A performance-oriented sealed 520 option. Confirm the chain maker's current application limits, length, and master link.
Related product
DID 520 ERT3 Chain
A lightweight non-sealed race chain with a published 450cc maximum—not a generic choice for every track bike.
Related product
MOTUL Factory Line Chain Lube — 400ml
Use a chain-compatible lubricant sparingly after cleaning; follow the chain maker's seal and solvent guidance.
Sources and further reading
Specifications, prices, approvals, and track rules can change. Checked July 2026.