Exhaust tuning

[Outlander]

I have a 1980 GS550E. I have the bike running fine, thanks to the help of you guys. So today, I went out to the bike and looked at the exhaust. I have a large hole in the center of the pipe, and 2 smaller ones at the 12 o'clock and 6 o'clock position. Remembering what my father had told me, I took a 3/8's drill bit, and drilled out the 2 smaller holes, and then added 2 more, at the 9 and 3 o'clock positions on both pipes to help reduce back pressure.

What I got was a deeper sounding bike, with a touch less of back pressure, I am assuming. Will this adversely affect the bikes performance? I have taken her out for a few rides, plugs look normal, and she still runs okay. I haven't really noticed anything bad, but could something bad happen?

Any ideas?

[Calvin Blackmore]

well
um my bike rusted out its baffles and blew out the wadding

made a hellish loud noise till i found an OEM replacment set on ebay

it was freakign painfully loud
i was a bad bad man for driving it like that
it wasnt a nice rumble it was like a crappy old lawnmower

I got no increase or apparent decrase in performance
i dont think 4 strokes are benefitted as much as 2 strokes are by exhaust back pressure

[NetBSD]

i used to do this on old street and trail bikes (1982 yamaha XT250) all i noticed was a better sound, it ran for years liek that till i broke the sidecase when i layd it over

[Zook]

Where on the pipes did you drill the holes?
You want ZERO leaks between the head and exhaust tip. Any holes leans the a/f ratio.
Granted, some pipes have small holes at their lowest points to drain condensation but it doesn'r improve performance.
In fact, a hole in the exhaust may cause backfiring under trailing throttle because it sucks in air.

If you want more power get a better flowing exhaust sytem and jet the carbs to match.

[catbed]

also, not enough back pressure kills your exhaust valves.