some observations on my kz1000e

I finally got the bike (new to me) on the road yesterday. I had rebuilt the carbs (110 mains, 15 secondaries), set float height and done a bench synch, but not a full synchronization. Also removed the vacuum lines and switch, and plugged all the holes for the emissions device. The bike was running great over 3K rpm, but sounded like it was running on three cylinders at idle. Also very rich, apparently, with a few puffs of flame on deceleration. Anyway, I figured I wouldn't be idling much anyway and took off up to Mammoth Lakes (CA) on highway 395. At some point fate intervened and I noticed that the bike was running pretty good at all speeds. No more rough idle, no more backfiring. I had been thinking that one possible problem was the idle air screw setting (all currently 1-1/4 turns out) needed adjustment, but I'm still not too comfortable that I know how to do that. Now I wonder if I should just leave well enough alone. Would I just follow the instructions on that KZ650 carb tuning page that I've seen floating around here?

I had the accelerator pump disconnected at the rod because the diaphragm looked a bit dodgy. I didn't really notice any hesitation, though I never really grabbed a whole lot of throttle at once. My conclusion is that it is unecessary. Am I wrong? Anyone know where I can buy just the rectangular diaphragm? I don't need the triangular one, which I think is necessary if you have the vacuum switch-enabled accelerator pump.

I averaged about 38 mpg. Is that about right?

Thanks.

Not sure if anyone replied. But the bike probably ran better after warming up so you didn't notice the rich conditon anymore or it could have been one of the slides sticking or a jet bunged up that cleared. See if it still runs bad when cold at idle and then come back. The specs for the idle air are probably diffeent for your bike. You should be able to search for the spec. If its stock. 38mpg gal is not bad at all. The acc pump only needed when stock for the lean condition from factory. It smmoths out the throttle response rather than giving a "turbo" boost

The accelerator pump puts one spray of gas into the combustion chamber when the throttle is turned. It compensates for a lean, off-idle spot when using the #15 pilot jets and factory air screw settings. The air screws should be set when the bike is warm; start at about 1.5 turns out from lightly seated and find the highest idle for each cylinder. Then sync the carbs; 38 mpg not bad.

Does sound like a piece of dirt was still in there. Even if the diaphragm was somewhat hard or badly discolored (common issues) it is Ok as long as it doesn't leak. They run the replacement kit all the time on eBay. I think I got mine from GeorgeFix's or Z1Enterprise, somewhere around $25-30 I believe. Did yours still have the spring inside? If not the kits come with new ones.