Exhaust diameter

[wa1udg]

   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.

[Rob Valdez 79 R65]

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.

[wa1udg]

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.  

[wa1udg]

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

[nhmaf]

The exhaust nuts are the same on either side..

[wa1udg]

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.