78 KZ1000 Popping exhaust

Can someone help me on this? I just bought this bike a month ago and it had an aftermarket header with no baffle. I put a 4 into 1 vance and hines w/a competition baffle and 120 mains. It had 115's. I have 28mm smooth bores. It runs pretty good but I am getting some popping throught the exhaust maintaining 45 mph, and a little at idle. When I put the header on I noticed i got blueing of the pipes on all except one. The plug was carbon fouled and shiny. I checjed the carb and the air/fuel micture was set almost all the way out. It looks like the previous owner tried to lean that carb out but not sure. I changed the plug and set it helped temporarily but again got some carbon fouling but the performance is still pretty good on this thing. It doesnt break up at all when I get on it or opening it up. The popping though is driving me ape @!#$$. Can someone please help on this.

Thanks

jbrewer73 wrote:

...just bought this bike a month ago and it had an aftermarket header with no baffle. I put a 4 into 1 vance and hines w/a competition baffle and 120 mains. It had 115's. I have 28mm smooth bores. It runs pretty good but I am getting some popping throught the exhaust maintaining 45 mph, and a little at idle. When I put the header on I noticed i got blueing of the pipes on all except one. The plug was carbon fouled and shiny. I checked the carb and the air/fuel mixture was set almost all the way out. It looks like the previous owner tried to lean that carb out but not sure. I changed the plug and set it helped temporarily but again got some carbon fouling but the performance is still pretty good on this thing. It doesnt break up at all when I get on it or opening it up. The popping though is driving me ape @!#$$. Can someone please help on this. Thanks

Initial thoughts regarding problem cylinder--

If using pods, clogged air filter;
Float bowl fuel level too low or too high;
Air intrusion at carb holder (crack), or loose clamp; or old hard vacuum plug;
Correct air screw setting.
All these are quick easy checks without removing carbs.

Before delving into carbs, would check compression figures and verify valve clearances.

Good Luck!

Post edited by: Patton, at: 2007/06/05 05:32

Mr. Brewer! Did you buy this bike, jump on it and just want to ride? You bought a "vintage" bike which requires some care and feeding. Buy a Clymers manual and perform a FULL tune up and replace some rubber bits and gaskets. I suggest you replace the exhaust gaskets, the carb holders, the vacuum caps on the carbs if any are fitted. Since there is no 28 smoothbore, I would figure out what type carburetors are on the bike and read previous threads on jetting that particular model. Most all popping is air leaking into the combustion chamber or the reed valve emissions stuff. Since we don't really know what bike year/model you are talking about, more specific tips can't be made. Please take the time to edit your profile and put your bike year/model and possibly your location in the event local help might be available.

Thank you, appreciate the input.