RM125N

[crankpin]

Got them, cheers 

[mainline]

Yep, i've got a pe175x I use in mx. Really nice motor

Any closeups?

Cheers.

Sorry, what I meant was I have an actual PE175X that I use in MX, not a PE motor in an RM frame. I did plan to swap the motor into an RM125 frame that I had, but at the end of the day I couldn't see the benefit given the frame dimensions seemed so similar when I had them side by side. I ended up just stripping gear off the PE and using it as is.

[mainline]

also, the rear engine mount span on the '81 175X motor is 74.5 mm if that helps? I'd assume the 1980 model used the same cases, not sure if 79 was a follow on from the 78 RM though, and different as a result.

[crankpin]

&9/80 RM125 was the same.

I'll measure up my rear engine mounts tomorrow.

[lukeb1961]

Sorry, what I meant was I have an actual PE175X that I use in MX, not a PE motor in an RM frame. I did plan to swap the motor into an RM125 frame that I had, but at the end of the day I couldn't see the benefit given the frame dimensions seemed so similar when I had them side by side. I ended up just stripping gear off the PE and using it as is.

I have recently been discussing (via e-mail) the PE with John Morgan and Drew Smith of Team Suzuki fame from back then. Drew (or John, maybe it was John) makes it clear they took the RM125 frames and tweaked for the PE model. So yeah, the dimensions are likely to be very similar.  Here is his description of the PE175Z full-floater:

"With the PE 175, we decided to build the full floater which we revised the frame from a RM 125, built the swing arm to incorporate the quick change hub, ported the engine for performance and crated it up and shipped it to California.  We met with a group of engineers and went over the bike in minute detail.  They made one change.  We had made a rod actuated rear brake going through the swing arm bolt to eliminate any feedback due to the swing arm movement.  They were afraid of that for safety reasons and stayed with the cable actuated brake."

Luke

[mainline]

Yeah, there was very little difference between the pe175x frame and rm125n frame that I could see. Mostly brackets and ancilliary stuff.
The only major thing was the frame upright and shock bracing area on the LH side.

[vmx42]

I wonder what the weight difference is between the PE and RM frames? 

[mainline]

Probably a couple of pies and a beer or two?
One minor thing I found peculiar, the PE used 10mm shock bolts, while the RM used 8mm?
I would have thought it'd be the other way around if anything