Are we too loud?

[Bob Bean]

Lew,
dont have any pictures of it.
Dont know if I can explain it well enough for you to visulize it, but will try.

Think in terms of a regular muffler with a large opening at the exit.
there were 3 metal bars across the opening with a small hole in the center where the metal bars met in the center.

There was a round metal circle of metal with a round rubber flap rivited to this 3 bars in the metal.  With just a slight tension against the back side of the muffler.  The exhaust would push the flap away from the back of the muffler.

What we did was drill out the rivet in the center of the metal/rubber flap.  Then we welded a 8mm nut in the center of the 3 bars.   Then we took a 8mm bolt about hmmm oh, 60mm long ran it thru the nut that we had welded to the tri-bars.  From the inside out. Then we welded the round metal/rubber flap to the end of the threaded part of the bolt sticking out of the back of the muffler.

By turning the round metal/rubber flap in to the muffler, it tightened the rubber flap up against the back of the muffler restricting the exhaust flow and making it very quiet.

Then you could reach back, turn the metal/rubber flap counter clockwise out and it would have a big gap away from the end of the muffler, letting the exhaust flow freely...  It could not fall out of the muffler because the end of the bolt would only let it come out so far....

Hope this helps you visulize it...  
Otherwise I will have to get out the crayons and try drawing pictures.  

Bob

[Bob Bean]

Lew,
If memory serves me right, I think it was old Huskys that had this rubber flap on the end of the muffler....Dont remember what year/model

Bob

[Lew Mayer]

Thanks, Bob. I think I got it. I failed crayons in school anyway.[)]

Lew Mayer

[Dale Fisher]

While reviewing a French magazine from 1975 I noticed this Sachs powered BPS.  Obviously there was great emphasis on eliminating any vibration noise from the cylinder.

[David Laite]

There you go, used heater hose, 1001 uses! Noise was a concern even back in 1975 in many parts of the World. Nicely made bike, notice the continuous weld on the frame gusset beneath the fuel tank.

1973 Penton Six Day
1973 Penton Jackpiner
1982 Yamaha XT200
1982 Yamaha XJ650J Maxim
1984 Husqvarna 400WR
1987 Yamaha YZ490
2005 Honda CRF450R

[brian kirby]

Oh my, look at those horrid foot pegs!

Brian

'72 Berkshire

[Dale Fisher]

Here are a couple of overall pictures.  Note this is advertised in two models 125/175 both in these pictures (same lower end).  Look at the ultra-quiet exhaust must have been the ultimate for river crossings