Sunday, July 20, 2008

Exhaust mod.

While I like a quiet bike, I thought the exhaust was a little restrictive on my bike. Maybe it was my imagination but I thought I could tell the header pipe was not flowing as well as it should.

With the muffler only having a 11/16" outlet, I decided to drill some holes to open it up. I selected a 7/32" bit and drilled one hole. I figured the small hole could easily be welded closed if I didn't like the effect.

After drilling one hole (I left the bike running to hear the noise difference) and listening to only a slight increase in the noise level even at higher rpm's, I drilled a second hole. Now the exhaust only has a slight noise increase and I stopped the drilling. If I were to do it again, I think I would put one larger hole instead of the two.

The engine appears to breathe a little better but it may just be wishful thinking. I can no longer hear the bottleneck in the header pipe and the bike seems to perform better above 5,000 rpm's.