Carb tuning issue

I am helping a friend with a kz740-4 he picked up recently not running. First thing I did was completely disassemble the carbs (not sure what kind they are, they look like these [img]http://http://kzrider.com/archive/images/public/img-1095907948.jpg[/img]

Soaked the bodies and all metal parts in carb dip, re assembled, blew carb clean through all passages, blew out with compressed air, etc. Reassembled and installed, and now it runs. The bike has pods and 2 2-1 exhausts. Installing the factory airbox isn't possible.

The problem is, at idle with the choke on, the LH pipe consistently pops out fireballs, the RH does not. Can ride pretty decent with choke on. Take choke off, its totally different. Wont idle without dying, flat spots and popping while riding, etc.

I have rebuilt both sets of carbs on both my kz's (twins) and never had a problem. Those carbs are also a completely different style. I wasn't aware I was doing it at the time, but when I disassembled them I messed with the needle adjustments, at least that's the best I can figure out what those screws do. Where should those be at? Its (I think) #24 in this picture

Any help with this would be appreciated!

This might be a really dumb question but have you done the float heights etc yet? I've only worked with a single, but I think I had similar issues to you.

I'm assuming the fireballs you're describing is the result of that carb backfiring, which could mean you're mixture in that one is too lean, your ignition timing is off, spark plug could have issues or valve clearances.

The choke on choke off issues were solved in my instance through getting the jetting ok, and seeing as that's all about the fuel/air ratio it sounds like what you've done with the needle adjustments may be responsible for that. In my case, all my idling issues were in the end related to my pilot jet and its system (I hadn't screwed it on properly).

The manual should state what setting the needle should be at?

Your carbs look way more complicated than mine. Good luck with it.

You are surely running lean. With pods, you'll have to go up to the next pilot jet size. With the stock pipes, I think it will run OK with the stock jets. If not try one up from stock. Bob

couple of corrections to my above post. its actually a kz650-4, not a 750. Also, I went in the manual and found out how to set the needle height and did that. Backfiring issue is solved, but the choke issue is still there. Runs fine with choke on, and I can get it to about half off before it wont idle, I am now leaning towards a vacuum leak.

Your friend will no doubt need to become more than a little familiar with re-jetting if the bike currently has pods and stock jetting. Ed

I had same issue, first thing make double and triple sure that the pilot circut is completley free of build up, they make wire cleaners to poke through jets and fully clean them. You getting the fuel you need with choke on and starvin with it off, so at idle when pilot circut is in control your getting less fuel than needed. Most rebuild kits supply new pilot jets because they are hard to clean. Also bench syncing is very helpful it's in manual. Happy ridding

nitrochristian wrote: they make wire cleaners to poke through jets and fully clean them.

Where might I find these wire cleaners?

jsanch08 wrote:

nitrochristian wrote: they make wire cleaners to poke through jets and fully clean them.

Where might I find these wire cleaners?

Click here > www.z1enterprises.com/ItemDetails.aspx?item=KL35-3498

Good Fortune!

As a rule the clip on the needle should be on third grove (middle grove) if your needle has groves. Some only have one, then its a shiming issue for fine tuning.

Carbs are still dirty, clean them making sure all the little passages in the badies are clear.