KTM 100.....or Sachs top-end conversion.

[rob w]

I remember Mike Lenz had this project in the works, of putting a Sachs top-end on a KTM engine. I just wanted to share something I found in a mag.

In the 1977 U.S. Reliability Trials Series, Glenn Allison from Wyoming won the 100cc class in the series riding a Penton. There's a 2" sq. photograph of him and the bike in the Nov. '77 issue of Dirt Bike.
I can't make-out everything I would like from the photo, but it appears he's riding a '77 MC5 125 that's been converted into a 100. The head appears to look more like a Sachs head than a KTM head. (I can't be certain) But since it would seem easier to mount the Sachs top-end on the KTM lower-end than to have a custom sleeve made and find the proper piston, I can believe that's just what he did.

There may be two people that can help answer this question. Dane for one, because he knows more of what went on than anyone else. Or else, I think I remember John Durrill talking about a friend by the name of Rick Grant from Florida, well Rick Grant was Glenn Allisons' nearest competitor in that class riding a 100 Hercules. And alot of times a guy knows what his competition is riding.

Anyway, just thought it was a interesting subject, and find.

Bob

[firstturn]

Rob,
  Remember that Rocket had a 1977 100 Penton that he sold.  I had seen a similar bike built for 6 day  teams back in the day.  Rick is a good Friend of Dougs so maybe he will come on and expain what he knows.
RC

Ron Carbaugh

[john durrill]

Rob,
 Is this a project you are thinking of? If its is. I can go over what we found when we did our conversion.
 Monarch used KTM top ends on the Swed. Team ISDT bikes in the early 70,s.
They used the 175 ( tall piston)  and a stroked A engine with a 175 top end to compete in the 200/250 class. 63.5 bore x61mm stroke
John D.

[Gary Roach]

Rob,
  L.A.Sleeve made a sleeve for the 125 KTM cylinder, and it used a 48mm Sachs piston. One of my good friends, James Giddings, had one of these with a GEM reed kit on it, and he rode the 100cc class at the Blackwater 100 in the late 70's. He usually finished in the top 3 in the class. I have this complete top end in my garage.

[firstturn]

Gary,
  L.A. Sleeve made many such mods for a lot of different brands.  I have a 100cc set up made by them then sent to either FMF or J&R Racing back in '75.  Neat stuff that people still have around.  [^]

Ron Carbaugh

[john durrill]

Ron , Jerry can you shoot some pictures of the cylinder? It would be interesting to see what the ports look like on the 100 sleeve.
John D.

[rob w]

Gary,

Thank you, that explains my bewilderment of the KTM 100. I don't recall ever hearing anyone speak of that engine before. The oddity and rareness of that confiquration ranks as high as anything I've heard of. The group of you (Kent, James, and yourself) certainly reeled-in some wonderful, unique machinery over the years.

H. Hopkins of New Jersey may have also ridden one of these in '77, he's mentioned in the same article as a Penton rider in the 100 class.

Tell Toni for me, I think the picture of her that's shown on this site under "04 Mid-Ohio racers", is a great photo and the best of the bunch.

Thanks again for jumping in here and clearing that up, I know we don't hear from you often enough.

Bob

[Okie]

I did that on my 76 Penton ie. KTM.  It was a stright bolt on instalation.  I didn't use gaskets on the base or on the head.  Lowered the port timing for more torque and higher compression.  I never had any failures with the 100 KTM but when I got bumped to the A class I killed several pistons in the stock 125cc cylinder and head. Never did figure what was going on with the 125 stuff.
See Ya
Okie;)

Have fun and the day will take care of it's self.

[john durrill]

OKie,
 Which cylinder and head did you use? can you remember any more details of what was in involved?
Thanks,
John D.

[Gary Roach]

John,
   It looks like the only modification done to the cylinder was some clean up work on the intake port for the GEM reed kit. The stock 125 cylinder head was used. Other than matching up the ports, it looks like the only thing done to the sleeve was some notches cut at the very bottom, front and back,(where it goes down in the cases.....maybe to clear the rod?), and also the "V" shaped boost port looks like it cut by hand. The Sachs piston was stock except for an oblong hole cut in it just below the lower ring for the reed kit. Email me at [email protected] and I'll send you some photos.  

Gary