125 KTM - 100 Sachs hybrid engine

[Paul Danik]

In issue No. 26, the September 1976 issue of Keeping Track, The Penton Owners newsletter put out by Penton Imports "back in the day", there is an interesting tidbit about a Sachs / KTM engine combination.

According to the short article with an accompanying photo, Carl Cranke built Robin Bennett of Mason, Iowa a 100cc machine with a 125 KTM bottom end and a Sachs 100cc topend. Robin went on to win the first two outings with his innovative machine, according to the article.

Possibly you guys already know all about this interesting engine combination, if not maybe some of you engine guys might find this an interesting winter project.

Paul

[brian kirby]

I have never heard of this, but most here know about the John Durrill Sachs with the KTM 175 top end on it. When AHRMA created the 100 class in '09, John's Sachs/KTM 175 made me think about building an engine exactly like the one mentioned in the Keeping Track article, a KTM bottom end with a Sachs 100 top end. After thinking about it for a long time, I decided not to do it. I decided that the only real advantage to an engine combo like that would be better shifting, which would not be an insignificant advantage, but the weight added by the KTM bottom end would more than counteract the improved shifting. I will probably catch some heat here for this, but I think the Jackpiner is too heavy for its power output, a 100 would be even more so.

Those are all just guesses on my part though, the KTM/Sachs 100 might be a fantastic combo, no way to really know unless you do it. It would be an interesting engineering exercise for sure.

Brian

[rob w]

It's been done by Mike Lenz.

http://pentonusa.org/forum/topic.asp?TOPIC_ID=5487&SearchTerms=100

http://pentonusa.org/forum/topic.asp?TOPIC_ID=8469&whichpage=1&SearchTerms=100

[brian kirby]

I forgotten about Mike's bike. He pretty much confirmed what I suspected, the added weight is a big detriment, especially if you can tolerate the Sachs shifting. I had thought about the total weight of the KTM bottom end, but I had not even considered the weight of the crank slowing RPM response.

Brian