350 vs 400 transmission

[Czakky]

I'm about to get started on my RD350/R5 project and am torn on what to do for my transmission. RD350 or RD400...
I've been recommended both.

What's your guys' experience?

[SUPERTUNE]

No question...400 gear set.
Yamaha learned, Use their example.
No reason to look for performance and go backwards.
No one I know that has a slight idea of the gear ratio spreads would recommend the 350 ratios.
Chuck

[Czakky]

How will a 17/40 sprocket combo work with a 400 trans?

[Jspooner]

17 countershaft is too big for a 350 no matter which trans you use. You're going to want a 14 or 15 most likely depending on what you do to your motor. But like Chuck says, use the 400. It's the only way to go especially with a hot rod motor.

[Czakky]

Yup, the 400 trans is in. So looking at gearingcommander.com it shows the RD400 with 14/40 sprockets running 76mph at 7500rpm.

What is an okay cruising RPM?
I'm not trying run to Cali or anything but I'm trying to keep a decent balance.

This is on a stg2 Supertune with Spec 2 classics.

[Organicjedi]

RPMs are high for my taste at that speed for a 400.

My stg 1 supertuned 400 with Spec II classics and 15/39 gearing is at about 75mph at about 6500 in 6th. It's plenty rowdy off the line but still has room at the top to "comfortably" cruise and pass at freeway speeds. Cause we all know how comfortable 80mph feels on a naked 350lbs bike. (We're not riding goldwings) but I don't have to wring it out to get and stay there.

You'd probably want more revs from a 350 motor though

[bhh1989]

Don't forget you have to also get the 400 clutch hub if you are buying just a transmission. The splines on the shaft are different between 350 and 400.

[Czakky]

Got it. Installed and ready for the power side!

[SUPERTUNE]

When using the 400 clutch hub, you will need to grind down some ribbing under the clutch cover to clear the 400 clutch.
I have some pics somewhere. I think I have them on my phone I can download later.
Chuck