The New And Improved Unofficial R65 Forum V2

General Category => Totally Off-Topic Discussions, Rants, Tire & Oil Threads, Etc. => Topic started by: wa1udg on September 15, 2011, 11:14:30 AM

Title: Exhaust diameter
Post by: wa1udg on September 15, 2011, 11:14:30 AM

   Looked at the bike on my way to the car today and it sure seems that the exhaust exit on the left side is bigger than the that  on the right.  I think I will measure it tonight.  OEM pipes.  The left side is the slightly longer one.  H. S.

Title: Re: Exhaust diameter
Post by: Rob Valdez 79 R65 on September 15, 2011, 02:37:52 PM

Diameter or length?

The left cylinder is slightly forward of the right cylinder.  This is due to the fact that the connecting rods are offset on the crankshaft.

Some bikes, like Harley-Davidson have one con-rod "forked" with the other in the center of the fork, so there is no offset.

Stand up on your footpegs and look down and you will see what I mean.
Right carb is further back than the left.
Even the right footpeg is further back than the left.

(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F138090618.jpg&hash=a083a9ad447110595729f9c8cee62a2b1bb61249)

Title: Re: Exhaust diameter
Post by: wa1udg on September 16, 2011, 03:31:44 PM

The hole in the end is bigger.  Probably to compensate for the longer pipe length.  My rough measurement indicated at least an eighth of an inch larger on the right side.  

Title: Re: Exhaust diameter
Post by: wa1udg on September 16, 2011, 03:40:06 PM

BTW if you want to see crazy con rod setups, look at a multibank radial aircraft engine, the ones that got the nickname "corncob".

Title: Re: Exhaust diameter
Post by: nhmaf on September 17, 2011, 10:31:13 PM

The exhaust nuts are the same on either side..

Title: Re: Exhaust diameter
Post by: wa1udg on September 18, 2011, 10:44:45 AM

OK, I've got a ZEUNA 212 oem  muffler on the left, and a ZEUNA 213  oem muffler on the right, and the LEFT muffler exhaust outlet is at least an eighth of an inch larger in diameter.  Hopes this  reduces the confusion I caused.  May mean nothing at all.  A little coating of exhaust residue hides the difference, but in this case I had just polished the mufflers to a nice shine.  H. S.