Running chambers on different models?

[Twidget]

I think this was asked on the old forum, but I'd like to resurrect the topic.

Is it acceptable to swap expansion chambers designed for one model onto a different bike? I have DGs for an RD400 (that were represented as RD350 pipes by the seller) and Factory Pipe 's for an RZ350. Would there be any issues with running either of these on an RD350 after relocating the mounts as necessary?

[Dvsrd]

I think this was asked on the old forum, but I'd like to resurrect the topic.

Is it acceptable to swap expansion chambers designed for one model onto a different bike? I have DGs for an RD400 (that were represented as RD350 pipes by the seller) and Factory Pipe 's for an RZ350. Would there be any issues with running either of these on an RD350 after relocating the mounts as necessary?

I have no experience with either of those pipe models, but I would not hesitate to try either of them. From the theory I have read on 2 stroke exhausts, the length is normally determined by exhaust port duration and target rpm for peak power. The RZ has more duration, while the 400 has less thanthe RD350, and there are differences between the various 400s as well. Most likely, you will have to elongate the stud holes in the flanges, remove center stand (and possibly bend the tabs) And relocate mounts, as you say. I have used RD400 Allspeeds on my RD 350, and they worked ok. So just go for it!

This nice, custom RD is using RZ pipes, so it can definitely be done: http://www.bikeexif.com/yamaha-rd400-custom

[Jspooner]

You can make RZ pipes work on an RD but it's a bit of work, more than swapping RD350 and RD400 pipes. The main problem with using RZ pipes on an RD is that RZs have power valves so the power curve on an RZ is way different than an RD which means a different pipe design. Like I said, it does work but they do not work nearly as good as a pipe designed for an RD.

[2steve]

I'm running Factory Pipe Products (FPP) DS7/RD250 pipes on the RD400.  It takes some adjustable swinging bracket adaptation at the fastening points near the back, but they are fantastic: