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Mac 2 into 1 race header and muffler

B

blkb1rd

New member
Good day all... Has anyone used the Mac 2 in1 racing header and muffler system...model AC6-0903... Thinking of adding it to my R75/6... (Slowly turning it into a cafe).... I know I would have to change carburetor settings if not changing the jets... So I seek the wisdom of the brotherhood of airheads... As always thank you in advance

Tom Casey
2016 R12RTw Papa smurf
1975 R75/6 Ole Yeller
 
Greetings
I don't have the Mac, but i do have the Luftmeister 2 into 1 (hanging in the rafters). This provided no increase in power and gave the bike enough "voice" that I cringed on early mornings when starting the bike up. I kept the baffle wrapped in fiberglass and it was still just too loud for my taste. I found also that on long rides the exhaust sound added to wind noise and I got fatigued sooner. I have seen pictures of the Mac and compared to the Luftmeister the style is, um, utilitarian.
See entry #134 on the post a pic of your airhead for a good shot of the Lufty
 
Similar to Bobs Luftmeister 2 into 1, mine is hanging on a hook.

It was included with the purchase of a Heinrich tank 10 years ago.

I installed it for a brief time even after being advised that it would adversely effect performance unless the flywheel was modified, a different cam installed as well as re-jetting the carbs.

It looked good and sounded great but lost bottom end torque and nothing was gained at the top end.

It was on the bike for a hundred miles or so before going back to the original exhaust system.

Of the modifications on my R90/6 it, along with mounting the biggest tires that could be fitted to stock wheels are the only ones that have caused me to revert to stock.

Bill
 
Last edited:
I'm very interested in the two hangers so to speak. I fully understood that rejetting would be needed BUT the change the flywheel THATS A NEW ONE.. If either one of you wants to make space on the wall/rafters let me know on the down low (yes selling things here is VERY BADD. Am I to take it that neither of you changed jets or settings?

Tom Casey
1975 R75/6
 
I am not a tuner, but re-jetting as far as i know saves the engine from self destructing when a change is made to the intake or exhaust side of the jugs.

The Luftmeister pipe that I have is for a bike that is tuned for racing. Putting it on a stock R90 that is dialed in for street use actually decreased its performance. (it did sound great)

Some of the changes besides the tank are, R90S handlebars, bar end mirrors, electronic ignition, rebuilt and ported heads, Siebenrock barrels and pistons, Racetech Goldvalves for the forks, and Works shocks.
The engine has a bit more torque and has less vibration since the top end rebuild.

IMG_0570-1.JPG
 
tanker4me said:
I am not a tuner, but re-jetting as far as i know saves the engine from self destructing when a change is made to the intake or exhaust side of the jugs.

The Luftmeister pipe that I have is for a bike that is tuned for racing. Putting it on a stock R90 that is dialed in for street use actually decreased its performance. (it did sound great)

Some of the changes besides the tank are, R90S handlebars, bar end mirrors, electronic ignition, rebuilt and ported heads, Siebenrock barrels and pistons, Racetech Goldvalves for the forks, and Works shocks.
The engine has a bit more torque and has less vibration since the top end rebuild.

View attachment 81328
Click to expand...

NICE...
Tom Casey
1975 R75/6
 
Once upon a time there were words at the historic racing association website to the effect that replacing the stock exhaust system with a 2->1 resulted in a performance loss.

It certainly and obviously reduces the volume of the exhaust system. Of course with the crossover in the headers, the volume available to each individual cylinder is the entire exhaust system, both left and right. With individual pipes with no crossover, it isn't and of course one muffler is essentially half the volume of two.

This is visual performance only ... and deceptive. Not so certain the weight reduction makes up the difference.
 
I would like to thank all of you for your input... It would appear that the two and one idea though looking good is not practical... I will stay with the stock exhaust system... Though at the moment that all is a moot point... I went for a ride on the bike yesterday... I cranked it up to look down and see gas pouring off the left carburetor... After shutting down and pulling it out of the garage... I started up again at this point no gas coming out .. The engine started right up but after 30 seconds it quit and will not restart now... It sounds like I have a problem with spark... So a fancy exhaust system is really not at the top of the list anymore

Tom Casey
R75/6
 
blkb1rd said:
... I went for a ride on the bike yesterday... I cranked it up to look down and see gas pouring off the left carburetor... After shutting down and pulling it out of the garage... I started up again at this point no gas coming out ...

Tom Casey
R75/6
Click to expand...
There are a number of possible reasons for that to happen.
When it doesn't repeat itself, I'd be inclined to suspect that the cause was a small particle getting stuck in the carb letting it spew out gas. I've had grit keep the float from raising as the bowl filled and spew a mini river of gas out. That can fix itself, but, even if it does it usually leaves the grit (or whatever it is) in the float bowl.

First thing to do would be to clean the tank, float bowls, and fuel lines and replace the fuel filter(s). If that doesn't solve the issue, new gaskets are relatively inexpensive and if needed rebuild kits are very reasonable.
Good luck.


Sent from my SM-G960W using Tapatalk
 
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