are idle and carb problems caused by exhaust?

good afternoon gentlemen,

here is my problem and i am sure i will get some fine opinions on it:

i have a '77 kz1000 (1075 wiseco, .410 cams, 28mm mikunis off a z1r, dyna). i swapped the rusty aftermarket 4 into 2 exhaust a couple of years ago to some very cool drag pipes. these are four individual pipes with no baffel or muffler that end roughly about the front footpeg area. they look great and are surprisingly quiet, no louder than an unbaffled kerker. the bike was not running well at the time so couldn't tell if the pipes changed the performance. since then i have improved many things (see above list) and found that the bike would not idle smoothly and would often almost stall and then when i bumped the throttle the idle would continue to climb to about 1500-2000 rpms. i believed that it may have been caused by the choke seals that wired george has often described as a problem with mikunis. i then swapped the stock 26mms with the 28s off the z1r and while the bike ran immediately better, the idle problem continued.bad seals with these too? i don't know. timing, compression, etc are all ok.

i suspect that the pipes are the culprit but am not sure. any ideas?

thanks-john

It's quite possible. Changes to exhaust are not much different than changes to intake. A free flowing exhaust will affect jetting. Maybe not as much as removing airbox and going with pods. I suspect you will have to rejet. As a "rough/uneducated/amateurish" guess I would say 1 jet up for intake mods and 1 jet up for exhaust mods. Don't even think to ask me about air and pilot jets. A proper plug chop is needed to check main jet size. Put in fresh plug, ride for 1/4 mile WFO throttle, hit kill switch, coast to stop, pull plug. White too hot, brown just right, black too rich. I am sure a carb guru will be along shortly to put you on correct path.