Exhaust question

[gregb]

Hi. I am curious if the exhaust on my R65 is original or aftermaket. Externally it looks like every one I can see in photos but the mufflers on mine are effectively an open pipe, apart from dimples protruding into the bore. It has a great sound but I'm not sure the originals would have been this loud in 1985.They have no markings and are mild steel, not stainless.

The reason for asking is I am wondering if the difficulty I had getting the carbs set up right could be due to these being open. It's running well and sounds terrific ...but just thinking. G

[skippyc]

It must be a south Australia thing. My bike come form there and it had norton stile straight through mufflers and sounded loud and good, but they rusted out and the replacement ones are quiet.

[georgesgiralt]

Hello,
if they are oEM, they SHOULD have the mandatory markings : ZEUNA (name of the maker) and some other marking like the BMW P/N and a BMW logo and other markings I do not remember right now.
If they bear none, they are adaptable parts or pattern parts.
If you have to replace them, may I suggest you look at Keyhan ? They are wonderful, sound like the OEM and last forever. I've no affiliation to them but use a pair since 1996 and they are and look like new....And I ride  a lot in all weather from -10°C to +50°C ... Shine or rain.

[gregb]

Hi, thanks for your reply. I will look at the Keihan if these rust out, but they seem fairly new. I think my question has been answered, these are definitely not OEM. Don't know anybody with an airhead to compare, but these are far too loud for a gentlemany BMW.

I do think they could affect the tuning though so will look at making some sort of removable baffle to experiment ... without making them too quiet.
Cheers, Greg

[ged in oz]

My bike came with a hand made exhaust system with hot dog mufflers on it! I replaced that abomination with some “Megaphonies” that I had lying around and they were stupidly loud as well.  It took me a while to track down an original exhaust system and the transformation was the best ‘modification’ that I made to the bike. It really did change the character of it and the way that I rode it.

I find that you need to keep it reving at 4-5K to make it actually work - I’m out in the bush - and loud pipes at that rpm are really antisocial! The quiet original pipes really encourage you to keep it boiling and it just transforms the whole experience.

The “cafe racer” craze has been throwing out plenty of original mufflers - not so much with headers, I had to import mine out of the US - so keep your eyes peeled and some will do doubt turn up at bargain basement prices.

[Kelvin]

The reason for asking is I am wondering if the difficulty I had getting the carbs set up right could be due to these being open.

Have the carburetors been serviced? Although it might be the exhaust I'd probably start with rebuilding/cleaning the carbs if the problem was getting them balanced. I'd also check the compression.

[gregb]

Hi. Yes, carbs have been fully rebuilt, new manifold rubbers etc. Compression is good and pretty well matched L/R.

Haven't played with Bings or a BMW previously so not sure what is normal, but they just seemed to be very sensitive to minor adjustment. Ok now after much fiddling.

I'm in the process of making up some restrictors/baffles for these mufflers to see if this does anything to the behaviour at higher revs. Experience with other bikes tells me it may change things, so I will advise if anything shows up.

I do like the sound they make, but people look around expecting to see something big and nasty coming ... and it's just a little BMW. Hilarious.