Will they fit? Kinda long (sorry)

I have a 78 KZ650 B2 or B2A. Either way I have a couple sets of carbs, I have one set which is the stock no frills set of Mikunis which the bike came with, I also have another set of Mikunis with the accelerator thing on the bottom. My main question is will they fit? THE BACKSTORY: I have had this bike apart about 80 times in the last 9 year for various repairs. (Inherited from a relative of my wife's, I would have sold it long ago, but it has emotional value and a lot of my blood) I took it apart most recently upon arrival to Japan to do valve shims, someone before (bike was inherited as I said) stripped out some cam cap bolts. Bought a new head and jugs from Ebay. Jugs are in the shed, head is on the bike after lapping and shims. Started it up today to put synch/tune the carbs. She ran like a champ, strong and all that. Got part way through and couldn't get the idle down under. Would shoot up to 3k and 5k and wouldn't come back down. Using the motion pro vaccuum gauge, vaccuum would go up to usable and then disappear, hoses and guage are brand new. Fiddled with the ignition (newtronic) it's all the way back. Checked plugs, they were pretty fouled. I cleaned em off, good spark, back in, now I have fuel coming out of #2 bore into the intake box and wouldn't run except with the choke on (full on it would race like WOT). Took the carbs off, everything looks pristine except the pilot screws. All 4 have the rubber o-ring gacked up. Would this cause fast idle? So I have the other set with the accelerator setup sitting in the shed and shook the dust off them. They need some TLC, but before I put forth the effort, will they work? Bike has the vaccuum operated petcock. I'm pretty much done with the current installed set as I've had the #2 problem numerous times already. Floats are set perfect using clear hose to check float level. Thanks for any inputs, tomorrow if needed, I'll post some pics. Thanks again!!

I would check the carb holders. My KZ650 had a similar problem years ago. It turned out to be very fine cracks on the surface of the carb holders where they mate with the head. There were no visible cracks anyplace else. If you can get the bike to idle low, try spraying carb cleaner where the carb holders mate with the head to see if it affects the idle. Ed

650ed wrote:

I would check the carb holders. My KZ650 had a similar problem years ago. It turned out to be very fine cracks on the surface of the carb holders where they mate with the head. There were no visible cracks anyplace else. If you can get the bike to idle low, try spraying carb cleaner where the carb holders mate with the head to see if it affects the idle. Ed

I agree with Ed, but to answer your question.... yes, the pumper carbs are a direct bolt on. They added the accelerator pump in I believe '79 to make up for leaner EPA jetting. The "standard" jetting for a 650 was 102.5's but with the pump jetting was dropped down anywhere from low to high 90's.

Thanks for the help. The carb boots are all new, within the last few years, as are the airbox boots. needed something more pliable. The old ones were all hard and cracked. Should I put the larger jets in? I'm running a Jardine 4-2 as shown in my avatar. That's the bike. Thanks again.

Stock jetting should work fine I would think. Stock was 102.5 jet, 15 pilot, and clip in 4th slot (from top). If it feels a little lean (don't know how much more those pipes flow from stock) then 105's would be next choice. Let us know.

BTW, the B2A is the California spec version of the B2. The only difference in the bikes was with carburation. Essentially minor jetting difference.

I'll check on the clip settings for the needles. I just ordered 4 o rings for the idle screws. I don't have 100 bones to drop on rebuild kits for the pumper carbs. They've been in my shed for a few years now more like 4 or 5. But thank you all for the help. I should have the o-rings in a week or so. More to follow then

Got the O-rings last week and finally got time to get to work on the carbs. I went ahead and was checking the clip settings, all were on 3, so moved to 4 as the baseline.

On another note, Trying to bench synch, I can't get the slides open to the .032 spec, #1 will, but the other 3, even if I back out the adjuster all the way, won't come open. The book says to back the Idle adjust all the way out, am I missing something?

Update #2 for the day...

I used the main Idle adjust in the center to give me enough play to adjust the slides. They are all spec'd to the .032 in initial setting. Happened to be one of the carb cleaning tools that had a smooth part. Anyway, so after that I checked the floats to make sure they were where they needed to be. All good. Installed, tightened everything up, double check, triple check. Kick her over a couple times, she fires right up. Little rough, but figure the carbs need to get fuel moving, since she died a few times. Then she died, wouldn't start back. It didn't run for more than probly 30 seconds at most. Anyway, so I put the choke on, and she kicks back, even gunshots out the back. Take the choke off, feels like she wants to go, but doesn't turn over. Any ideas??

Is the vaccume line conneted to the right port? Check to make sure the vaccume line is not cracked and that the fuel line is flowing enough gas and is not being starved.

New spark plugs NGK B7ES would also be a good idea. Cheap piece of mind.

Have you looked at and checked the timing?

Good luck ... you will get there.

the vacuum is connected to the forward most port on #2. I know the other two are the vent lines. I probly should pick up new plugs, have to find a store over here for them (Japan) shouldn't be too hard The timing worked fine last week before I found my carbs were gacked again. I played with the plate a little bit to see if that was it. I'll get it, just need a break before I grenade it.