1973/1974 Hercules 125 with Sachs 6 speed Question

[Rob Thatcher]

I'm helping a local vintage rider.  I helped him split the cases and it is a 6A engine but has a 6D cylinder.  I was not expecting to see a 6D cylinder on a 6A bottom.  The front of the frame looks similar to a Penton, but the exhaust is more like a steel tanker.  His exhaust is pretty rough, and I would expect Hercules specific parts are harder to find.

Was this a common situation with a 6A/6D? 

Thanks

[Stuttgartautoman]

Motoraider.com has a connection in Italy that reproduces several complete exhaust systems and parts for vintage bikes. I'm not certain on your engine questions.

[slvrbrdfxr]

Rob,
I'm not an expert on the Hercules bikes but have looked at quite a few pictures of these early 70's Herc/DKW bikes over the last couple years. I bought a 75 model Herc GS175 at Mid Ohio in 2021 and its been difficult to find parts to make the bike whole again. I ended up making a trip to Kitchener, Ontario this past October to buy a second 75 model GS175 parts bike that had the needed items I was searching for. My 175 has a 6A bottom end too but the alloy cylinder is factory fitted with a 60mm iron sleeve which is probably somewhat rare like the Sachs 125D cylinders. In the pics I've viewed of 73-75 Herc/DKW 125 bikes I've found online, none of them looked like they had a factory installed Sachs D cylinder. Like I said, I'm not an expert on these bikes, so anything is possible. I would think a D cylinder would fit the 6A bottom end without any modifications. My guess however would be that the D cylinder was probably not installed on your friend's bike from the factory. Once again, not an expert but my opinion on the subject. Would it be possible for you to post a few pics of your friends Herc so we can see what it looks like. Also please post a pic of the exhaust your looking for. I believe the exhaust is different from 73 to 74 models and also from the 74-75 models. That way we can see exactly which exhaust pipe you are needing. I've added pics of a 73, 74 and 75 below which shows the three different types of exhaust pipes they used. Look forward to seeing some pics of the bike and exhaust.
Dave McCullough

[Rob Thatcher]

Since he got it free and will probably flip it, I'm going to trade him a 6B alloy cylinder with a new piston, rings, bearing, pin and bore for the 6D.  Next time I'm there I'll take some pictures. The tank is red, but the pipe looks like the picture with no seat on it and has a Preston Petty rear fender

[Doug Knight]

In '74 I had a '74.5 Six-days with a D motor. At the time I weighed #20 more the youngsters and the Penton weighed +#10 more that the Elsinores that favoered in the class. The Penton had a D motor and very seldom did I loose a holeshot. The torque out of the D was awesome. I think mine was equipped 32mm Bing. On the D, it was all about the porting. I even had an internal rotor ignition that I would swap out depending on altitude, and on the race location. I was racing in Colorado then.

[slvrbrdfxr]

Rob,
Yes, if you think he will flip the bike then probably well worth trading him a B cylinder to get the D in return. The blue bike without the seat is my 75 175GS. If his exhaust looks exactly like the one on my bike and he has a red tank then I'd say it's more likely to be a 75 model 125GS rather than a 73 or 74 model. My bike had the original rear fender on it when I bought it which was a Preston Petty ISDT type with a taillight. It's possible I might be able to help with a pipe and will have to look through my stash of Herc parts. What is the issue with his pipe ? Does his pipe still have the big cannister silencer on it ? What part of the country are you guys from ?
Dave McCullough

[Rob Thatcher]

We're in Columbus Ohio area. The stock pipe is pretty much Swiss cheese from rust but does have the cannister style muffler. I'll check with Eliot

[Rdway60]

Maybe try Jake Fischer? I believe he may have some Hercules parts and knowledge about. North of Pittsburg.(412)999-1143 is what I have. Seems to me Sundays are the best to get ahold of him. Good luck!

[slvrbrdfxr]

Rob,
The pipe I mentioned has holes rusted in the head pipe. The rest of the main body of the pipe however is solid. If your friend's pipe has a good header, then I'd think the two pipes could be combined to make one good pipe. If not, I can check with another guy I met during my Herc parts searches to see if he has a good pipe or header.
Dave McCullough

[Rob Thatcher]

Thanks Dave, I'll let him know.  Still trying to keep him from using a hammer on it

[Rob Thatcher]

I worked out a deal to rescue the entire bike.  I'll be getting it home and evaluating everything later this week

[slvrbrdfxr]

Rob,
Sounds good. Look forward to seeing some pictures of what you have to work with.
Dave McC