not sure

not sure if this is the right place to post this because i dont know if it electrical or carb.

ok i have everything back pretty much stock on my 78 kz650..stock exhaust system and airbox. that solved my fowling out plugs every couole miles but i still have a little problem. when i let up on throatle and let it slow down i get some backfire through the left bank of the muffler..it idels a little rough but runs great up through all the ranges..any ideas on it would be appreciated...mustache

Sounds like you have an exhaust and/or vacuum leak.

If you removed the exhaust head pipes, did you re-use the old gaskets or install new gaskets?

With the bike at idle, spray some carb cleaner or WD-40 at each individual intake manifold and carb boot to check for vacuum leaks - an increase in idle speed will confirm a vacuum leak.

i think u hit it right on the head. i do have a intake leak on #2..i didn't have any more carb cleaner or wd 40 when i made this post but i do know..hadn't fixed the leak yet. i probably will tomorrow and will post back to let u know if that fixed it..pretty sure it will..i really appreciate your help.thanks a bunch

mustache

well looks like i'm going to need some intake boots..tightened them up all i could but still got a leak.guess it is got a crack in it..

You don't want to run the bike if there is a leak in the carb holders. I have personally holed pistons by ignoring small leaks there. Not worth the chance you take. Get the carb holders... www.z1enterprises.com has them for your bike.