The PE400 was not
based on the RM400N. The RM400 had no primary kick, long stroke, and bugger-all bottom-end. Instead, it was based upon the RM250/PE250, used its own hefty rod & piston, own barrel, etc.
The USA guys in Team Suzuki (John Morgan) at the time kept hankering for a bigger 250, so they asked for and got the PE400, which is a 5 speed, primary kick, with the same stroke as the RM250. Even the carby was kept as the VM36SS, as per the PE250, just with a different (2.0 vs 2.5) slide cutaway and a 6DH20 jet needle. (use the 6DH3 if you cannot find the 6DH20)
NO, the PE400 did NOT use the VM38. EVER. Only the RM465 and RM500 used the VM38.
Note also it has the hefty rotor/magneto (1192 gram) that the RM does not. In all, a pretty good engine with grunt and plonking power, and depending on who was measuring, near or more the same top-end power as the RM engine, despite being strangled.
The PE250/PE400 frame etc. are effectively identical, except for dampers, shocks, etc.
PE400T 85mm x 70mm (s) = 397.22
RM400C 80mm x 80mm (s) = 402.1
RM400N 80mm x 83mm (s) = 417.2
Ron Anchack has pistons and also has the SkiDoo 650 rod that is the only readily available alternative to the now rare -409 rod. Note that our own OldFart (Stewart) did all the sleuthing behind that rod and Honda shims, and a number of people on the PE list have successfully raced their PE400's with this rod. see: http://www.anchakandsons.com/pe400rodkit.html
Bucket loads of info on my skydrive
PE skydrive: http://cid-407d7ef0965d3991.skydrive.live.com/browse.aspx/Pure%20Enduro
RM skydrive: http://cid-407d7ef0965d3991.skydrive.live.com/browse.aspx/Racing%20Model
and the word direct to me from John Morgan was:
'From the “Suzuki News - Fall 78” quote: “Gary Edmond completed the Trial “on gold”, riding a PE 250 in the specialty machine-oriented 350class". This was our first effort in developing an engine for the PE 400. We had modified a PE 250 engine as a step towards the PE 400. Glad to get that straight--finally. We weren't talking about it so most of the publications had him listed as riding a PE 250.