Monday, September 16, 2019

BMW airhead Power Flow silencers revisited

 

These Power Flow silencers I scored a while back on eBay. When they arrived I fitted them straight off. The seller had reported that they were a bit too raucous so he had tack welded in some db killers. As I discovered not only were they db killers they were also very effective performance killers and the bike ran dreadfully at anything above 3000 revs.

Next step was to set about removing the tack welds. Not an easy job given the recess in the outlet of the silencers and the fact that the term tack weld was rather under playing the large blobs of weld that held the db killers in place. A good hour with a die grinder had the offending noise restrictors out and then back on to the bike the Power Flows went.
 

So, how loud would they be? Quite loud is the answer, rorty but not too offensive. Did they make any difference out on the road? Really, I'm not sure - louder always seems faster. In theory they should give a performance edge but it will have to be in conjunction with some carb tuning. In many ways though the R100RS is already more than fast enough for its brakes and handling. Fuel consumption is already on the low end of the scale so just how much of an upgrade adding more performance to the bike as it is is rather a moot point...

The Power Flows seemed like a fun idea to have a play around with but I'm not sure if they will remain a permanent feature. They look great but the original Beemer silencers are great things, models of German efficiency, whispering quiet but with no stiffling of performance. And in a way that is part of the charm of a BMW, to be whisked along at high speed without disturbing the peace.

Lower fairing removed due to imminent top end strip for oil leak.

 And a short movie to get the aural experience.
The popping was traced down to a leak on the headers.
Steam on r/h head is from a recent wash.


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