"R xxx" engine serial numbers?

[jj]

I have a 76 250 MC5 with a engine serial number of "R 257" (stamped in the usual place on both sides) and a 81 125 RV with a engine serial number of "R 499". Does anybody know what the R means?

John J Slivka

[Larry Perkins]

I know when the first 73 250's came into the country there were some with R numbers.  I had several motors that came from J.R. Horne's collection from out of Penton Central in Amarillo.  I have asked several people about them including the late Rod Bush and Doug Wilford.  Doug thought when I asked him that they were for dealers to learn the mechanics of them since they were new.  Rod said he believed they were part of the first 50 that were finger ported and sent as race bikes.  All I am referring to is what I have tried to find out about those 73 250's and don't know who is right.  I still have one of those R 73 motors but need a real good Mag welding guy to fix it for restore as the crank let loose once upon a time and did some fairly major damage.  I sold the rest of them over the years.  Anyone up for fixing this one?

Anyway, don't know if that helps answer any of your question or just muddles it up but that is what I know about it.

Larry P

[454MRW]

I have a 9-76 clock dated 400 with a R98 stamped up by the right hand front motor mount bolt boss, and BHR and some overstamped numbers starting with 3 and ending in 003 where the engine number would normally be. I have always though that it was an engine built from over the counter bare unstamped cases and stamped by the engine builder or something to that effect. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S

[Paul Danik]

I have several NOS frames that have no serial numbers on them.  I have been told that these are frames that Penton Imports would have had in stock in their parts department for use as replacements, supposedly the serial number of the frame it replaced would be stamped in by the dealer.   Could those "R" cases be replacement cases with the last three digits of the engine serial number stamped in?  Sort of following the concept that Mike mentioned.

It would be interesting to see if anyone has a Manufactures Statement of Origin ( MSO) with an "R" engine number listed on it?  

Paul