bore job for headers?

[barberad]

The kid I got this bike from must have heard from his friends about drilling holes in the end of stock pipes. Are the holes going to lessen the performance on a set of jardine aftermarket headers?
It is obviosly louder, and somewhere in the bikes past, someone must of had a little knowlage of what was going on. Headers, k & N filters and probably carb jetting. Is the backyard soup-up job going to give me real ugly spark plugs?

TopCatGr58, thanks for the help wih the photos, I suffer from a N.A.V.Y. (NEVER AGAIN VOLUNTEER YOURSELF) defficiancy!
We will have to redirect over to the lounge sometime and swap lies. CFAO-AIMD, Okinawa 1989-1993

[TopCatGr58]

Hey Barberad,

Well, I was a "dry water" sailor, and got out after 6 years myself!

I've got a 4-1 set of pipes on mine, with Indy filters, and I drilled 4 holes in my baffle to give it a little more "throat". I've had no problems with the extra holes vs the no holes version. I have gone up just 3 jet sizes from stock on my mains, and have decent tan plug color and performance! The XJ is a little different in tuning the carbs mostly for the idle/pilot circuit in needing to temporarily seal off the YICS channels in the head during vacuum synching, but aside from that, you shouldn't necessarily have ugly plugs...providing they picked a right set of jets!
T.C.

[skids]

I have an 81H with 4-1 Jardines, a K&N single drop-in replacement filter. My Jardind started running the bike poorly when the cone at the end of the exhaust came loose. From 2800 to like 3800 rpms there was not enough vacuum to open the automatic petcocks. I had to switch the petcocks to prime just to keep fuel flowing. Everything was fine again when I rivoted and sealed the cone in place.