Vintage BMW Motorcycle Owners

As I understand it, the outlet of the muffler for a 1967 R69s should be 46mm. I noticed on my bike the outlet is 40mm. The muffler diameter is correct at 100mm. I am not sure what brand muffler or header pipes is on my bike but I would like to restore it back to what it should be. Mark has verified that the part #18 12 4 090 089 from his site is 46mm at the outlet so I am seriously considering buying these. They are pretty pricey so I wanted to ask for feedback from anyone here who has a set of mufflers from Mark.

BTW if I do get these I will offer the ones on my bike to this group (mods pls delete if this is not appropriate)

If you are a paid member of this group,you can post in the "parts for sale" section. Good luck in your quest for perfection!

808Airhead wrote: ↑

Fri Sep 23, 2022 5:10 pm

If you are a paid member of this group,you can post in the "parts for sale" section. Good luck in your quest for perfection!

Thank you! Not quite after perfection otherwise I would just give my bike to Tim Stafford who is not too far down the highway from me. Thankfully for my wallet I am just after period correct parts and my bike doesnt seem to need too many of them.

I sourced from Huggett, and sold, those same mufflers (both the R50 - R60/2 versions and the R69S version) at Bench Mark Works for many, many years. They are correct, and fit as they should. What more can I say?

My question would be, do they have the correct internals? There are also mufflers out there that are too restrictive. BMW put some quite elaborate internal baffles and tubes and what not in these mufflers and some aftermarket are not nearly like that. The bike will only have full power with the right type of mufflers.

So, do these Mark Hugget mufflers have the original internals?

I have a set of Mark Huggett R69s mufflers.

While I cant vouche for the internals, I weighed one muffler at 3.5Kgs.
So obviously there is something in there.
They are dignified and quiet as I always remember a BMW to be.

Your call, or email Mark and ask him. He is a very knowledgeable fellow and I believe he has high integrity.


Regards

Mal
Australia

Don't know where else one would be likely to find parts for our bikes that would be any closer to originals than the parts Huggett makes/has made; he supplies parts for BMW AG, and independent parts dealers.
Vech's post seemed to say it all.

Getting any more period correct would be to a have a treasure hunt and source a pair of genuine nos mufflers, and then hoping they lasted as long as they did(n't) back in the day.

The question of do they have original design internals?
We can only hope not, that was the Achilles' heel of the originals; hopefully that same quiet tone was achieved with some improvement on the rust promoting original internals.
Best-
George

Our German friends from BMWeinzylinerforum.de have done quite a bit of research into the mufflers as sold for the single BMW's. They found that the usual replacement mufflers had twice the backpressure as the original ones with a serious decrease in power. As a result, Rabenbauer started to sell mufflers with the original construction for the R25 and R25/2 and suddenly bikes who ran only 80 kmph in the past now reached full potential at 100 kmph.

I am sure mr Hugget is great guy with a good reputation, but as long as we don't know how his mufflers perform, we don't know nothing. Saying that they look great and fit well doesn't say anything about how they perform. I have some aftermarket mufflers on my R69 that don't give full performance, I never reached the 100 mph limit. They look nice though....

Rust resistance is more about the materials used, not so much the construction. The aftermaket ones rust just as quick as the originals.

So I emailed Mark and asked if his mufflers had the original BMW internal baffle design. Here is the response I got:

That is an open question as BMW had various suppliers such as Leistritz, Eberspächer, Boysen and Zeuna. What is original?

The R69S silencers that we sell are according to the BMW/Boysen drawing, last altered in 1967. The R69S reaches the maximum HP as specified with these silencers. If that was not the case, we wouldn’t sell them.

Thanks for asking! That's good news. Now we know.