Fingers crossed this exhaust works. It is from a 1930’s R12 BMW. I had a larger inlet welded to mate with the R75 headers. I hope they do not restrict power in any way or make the tuning of the engine difficult.
The headers and mufflers connect OK and luckily the brackets on the mufflers line up pretty close to the exhaust hanger area on the R75/5 frame.
To connect the muffler to the frame, I had to make some custom brackets to attach the muffler.
I made a test set out of aluminum and everything worked out OK. My holes were slightly off but I corrected for that later.
Here is the test fit.
I took my brackets and a pocket full of cash to a local welding and machine shop. He replicated my brackets with stainless steal and put the holes in the correct place as per my instructions.
Stainless steel should withstand the heat, elements and keep its shape. I worried that the aluminum brackets I made would not do any of the above.
Here is the bracket attached to the frame:
There isn’t much room to work with in there but with the right nuts and bolts, everything went to together just fine.
The garage is done! Photos of the new bike-build-work-space to come ( i still need to tidy it up).
I started tinkering with the bike again. I have been DYING to mount the exhaust. Here is a small sneak peek of what it will look like. Some more tech tips and build updates coming soon!
Sorry there hasn’t been too many developments on the bike as of lately. I have been doing some ‘behind the scenes’ work (noodling around and planning). A few months ago we purchased mufflers to an old R12 BMW with hopes of adding them to our /5 project. Of course, they are meant for an entirely different sized engine, and different sized header pipes.
They will take some adapting and experimenting with a /5 engine. Some critics say it won’t work (not enough back pressure). Some say it will. Some say it is a total experiment. Every ‘expert’ i talk to has a different opinion. So we are gonna roll the dice. If they don’t work, we can always switch over to a ‘standard’ set of exhaust. If they do, then we’ll have a very unique, and cool exhaust system.
We got them in bare steel with hopes to have them coated in a way in which they won’t discolor. As they sat in my garage, the basic moisture in the air started to oxidize them and a light surface rust began to appear. So i figured it was time to get cracking on them, and get them coated before they get any worse.
I’m on the hunt for a bare set of header pipes. I’m not sure if EPCO or anybody else will sell them in bare steel… but we need them naked so i can get the headers, and the mufflers coated at the same time. I’ve sent off some e-mails but nobody has gotten back to me. I may have to contact the exhaust companies directly.
Muffler straight out of the box. The collar needs to be widened to fit over the header pipes.
After a few months, these poor guys started to oxidize. I cut off the old inlet collar and had new collars welded on.
The /5 header pipe fits nicely into the new collar. The old collars are laying beside the pipes.
I actually want to mount these upside down. The ‘correct’ way is with the longer fin on the bottom. i want the longer fin on the top however there is a slight notch on one of the pipes that you would see if they were mounted upside down. That notch happens to fit directly under the foot peg for the rear brake… so maybe i go for it?