XJ HEADERS

Hello everyone. I own a 1982 xj650 with 17K. I was wondering if anyone has had experience with MAC headers or other header systems on an XJ. My stock exhaust has holes in both sides on bottom and I'm considering a header. I'd like to know about midrange and top end power increases and low end power loss if any. And re-jetting that may need to be done.
Thanks

Bikes I've owned:
Sears allstate when I was a teenager long ago
1971 Yamaha R-5 350 2-stroker
1974 Yamaha Tx500
1976 Honda CB750 Supersport
1979 Yamaha XS1100 Special
1982 Honda GL500 Interstate
1996 Honda V45 magna

 

I don't know if availability is better for the 650's; I have a SECA 750, and my exhaust system was damaged not too long ago when someone ran over my bike in a parking lot. I searched everywhere to try to find either reasonably priced original parts or an old stock Vance and Hines, Kerker, or Jardine header. I couldn't find anything except the MAC systems.

So, I ended up getting the MAC 4-1 full chrome header. It's better quality and better fit than some of the derogatory posts about them had led me to expect. I had seen posts saying that they leak, but mine does not. It is quite a bit louder than stock exhaust, though. At idle it sounds a bit funny. At higher RPMs you'll get more of a sport bike sound, which, depending on what you're looking for, you may actually like.

Power-wise I can't say I saw any increase... it came up almost the same. I am not convinced my dyno tuning with it was done perfectly, though. I will probably go back for another run in a couple of months. What I can say is that the MAC 4-1 moved the peak torque down quite a bit, from 7000 to about 4000 RPM.

 

my 750 seca has had a jardine 4-1 on it since i bought it i love it. The sound is really sport bike like and i enjoy the look so much more then stock dualies. as far as power goes low end isn't the greatest but after 6k it's like a whole different bike. But it does need to be jetted i've fiddled and fiddled but i cant get it right. so im giving up and taking it to my local xj guru (he's raced and built xj's forever) and he will put pods on and jet it so it will run right.

 

Jardine here as well, came on the bike when I bought it a couple years ago. I have nothing to really compare it to. But the bottom's dinged up good, third pipe looks nearly collapsed. Gonna have to do something about that..