SPEC II Chambers ?

[Tommo]

Also bumping the thread.  I'm hoping to make the last round this season with the Rd350 and will be needing a set of chambers.  Years ago I had a really nice set of pipes on a 350 and should have just kept the pipes.
NOticed the Jemco site doesn't work.  anyone know what's up with that

[2steve]

On the K2tec pipe description (https://www.moto-works.jp/k2tec/rd400.html) this caught my eye:
  Carburetor jetting is not needed for street use.
  For use in racetrack, where prolonged high rev situation is necessary, increasing main jet setting is recommended.
Seems a little odd that a "performance pipe" would not require a jetting change.

I remember my RD friends telling me to jet up for the Kawi H1 triple expansion chambers and that just made it run rich. I probably should have jetted back down and might have gotten a little more of a top end hit, but never did.
RD's are very sensitive with intake changes always requiring some jetting adjustment - more so, it seems, than exhaust changes. Weight loss over stock is worth it.

[m in sc]

h1s usually need up 1 on the main but leaner on the needle. piston port motors are super easy to tune compared to a reed valve motor