I asked what's the gearing on a RD400. Read it all for a laugh. BTW those ratios for 1-6 are also wrong.
Copilot Search Branding
Gear Setup for a Yamaha RD400
The Yamaha RD400 is a 400cc air‑cooled two‑stroke with a close‑ratio 6‑speed transmission designed for sport riding. Its gear ratios are optimized for throttle response and acceleration, with a slightly lower 6th gear than many other 400s for better cruising efficiency.
Stock gear ratios (RD400C, 1976 model)
1st gear: ~2.55:1
2nd gear: ~1.85:1
3rd gear: ~1.50:1
4th gear: ~1.25:1
5th gear: ~1.05:1
6th gear: ~0.90:1
These ratios give the RD400 a quick 1st‑5th shift and a slightly overdriven 6th for cruising, which is typical for Yamaha's sporty setup.
Adjusting the gear setup
For more throttle response: Use slightly smaller rear sprocket (e.g., 13T instead of 14T) or larger front sprocket (e.g., 17T instead of 16T) to increase the 1st‑5th ratio. This can make the bike feel more aggressive in acceleration but may reduce top speed.
For smoother cruising: Use a larger rear sprocket (e.g., 14T) or smaller front sprocket (e.g., 15T) to lower the 1st‑5th ratio, improving highway feel but slightly reducing acceleration.
Close‑ratio modifications: Some riders swap in 400‑specific gears from a close‑ratio RD400 transmission to fine‑tune the 4th‑6th ratios for track or long‑distance use
.
Maintenance & inspection
According to the RD400 service manual, periodic inspection of the transmission includes checking for wear on gears, shafts, and bearings, as well as ensuring proper lubrication intervals
. The RD400 uses a shaft drive with a 14T rear sprocket and 16T front sprocket in stock configuration.
Tip: Always match sprocket changes to your riding style and road conditions. For track days, a close‑ratio setup with smaller rear/larger front sprockets is common; for commuting, a slightly wider ratio improves comfort at higher speeds.
If you want the exact OEM sprocket sizes and their effect on ratios, consult the RD400 service manual or a Yamaha parts catalog, as sprocket sizes directly affect the gear ratios and riding characteristics.
The 14 tooth rear sprocket must be rare. I won't be referring to Skynet for technical specifications anytime soon.
i was looking for a t500 bit of info a few mos ago. ai referenced my post, here, and had it ultimately wrong.
ai's database of info is just massive crowd sourcing. some things are ok but man, for stuff like this, open a fucking book i say.