carb rebuild and 1075 kit

I have been trying to get the bugs out of the B4 i bought and built. I installed the 28mm pumpers with the pump removed and 26mm bowls installed. Running 20 /120 jets. These are the carbs i was running on the 1075 until i upped them to 34mm.

I ride the bike 24 miles the other day and the thing didn't want to run over 3400 rpm.

I suspected a bad coil so i ordered a set of Dyna from Jeff. Installed them today and rode the bike. Had a fouled plug. Checked the plugs and the blasted thing looks lean.
Running open header so i can hear it run. I'll install the silincer and go for another ride and read the plugs again.

Probably end up installing 34mm carbs.

Not trying to hi-jack your thread just reading and keeping up with your progress.

I also use a long clear fuel line so it makes a big "U" and the trash stays at the bottom. It is a good way to check and see if trash is still in the tank. Roy

A bike I bought from California someone had tinkered with the fuel lid. When I would open it there was a big sucking noise and my carb would flood out. Took it apart and put it back together the right way and have had no problems since.
A really good fuel filter the kind that screw open for cleaning is the kind I would use and making sure there are no particles in the tank should be a no brainer. No matter how many times you think you clean the carbs out all it takes is a crap fuel filter and debris in the tank to mess up all the hard work you took when you cleaned your carbs out.
DoubleDub wrote:

Thanks for the guidance everyone! The problem does appear to have been fuel starvation due to a malfunctioning gas tank vent (that's what I call it when I break it) and the rust accumulating by the petcock. I was actually able to get it up to 9000rpms this weekend without the hesitation there used to be. I definitely think I'm running rich now, but I'll let the plugs tell me the truth.

Agreed. I don't have the really nice filters yet, but the screens on the petcock and the filters have been doing a good job of keeping debris out of the float bowls.

Everything is apart right now as I apparently completely missed the fact that cylinder #2 has never fired since I put the engine back together (making the hesitation at high rpm make even more sense). Found a sticking float needle. Cleaning the float seats didn't seem to make a difference as the #2 carb float was still dry. Ordered a new set of float needles from Z1E that should be here tomorrow. It had been mentioned before that my needles might not be correct as they have a rubber tip and the Kz900/Kz1000 with 26mm carbs should have all metal needles. I'm going to put the stock 115 main jets back in before reassembling. If that seems too lean (using choke method to test) I'll put the 120 main jets back in, but I don't expect to need to.

Go to a performance auto store like JEGS they sell inline filters that work great for motorcycles. If you need I can get the name. Also if my gas cap is not closed properly it will not run correct. Plus it is very dangerous...Russ

So...

After finding and correcting that I was actually only running on one cylinder (float needle was staying closed on one carb), that my timing was advanced quite a bit, and my advancer wasn't working, this thing goes like stink.

However, I'm still having issues at 5000-6000rpms. It's almost like a misfire where only some cylinders are firing. Sometimes it will pull through it and sometimes it won't, but it isn't as strong as it should be.

I ordered a colortune and I'm going to be sync'ing my carbs next, but I don't think carbs being out of sync would cause issues at WOT. I have gone through the carbs several times and I'm positive these things are spick and span now. Pulling up on the choke doesn't make things better or worse.

I'm going to verify my float heights next as I think fuel starvation causing a lean condition is still the most likely culprit at this point.

I have also moved the main needle up one slot (second from the bottom so it sits one notch higher) which has helped some, but not with my 5000-6000 rpm flat line.

Any other suggestions, I'm all ears! Thanks everyone for your input and assistance!

dd,
i tried 26vm with a 1075 kit...no go
tried 28vm..better, not right
this was all with proper jetting and needle clip as per the pro's
at this point you are looking at mucho bucks for 29 smoothies or a cheaper bs34 upgrade
yeah, you ll need boots and filters, but in the long run you will have way more responsive carbs...i noticed a big difference even with crappy emgo pods and jetting that was off..i ve since put on k and n and re-jetted...talk to otaker about what you need....mine are good enough for what i need....i can finesse 7k+ as i need to as i want to do other things like put flowmasters on the 'rauder......good luck......keith

I have a hard time believing I need to go to different carbs with stock cams and no porting on my head. The amount of air the head flows shouldn't have changed much just by increasing the displacement. Definitely in the future when I do choose different cams, I'll most likely be having the head ported and putting different carbs like the Keihin CSR 29's on, but for now this things should run fine with the 26vm's if I can work out all the issues.

I'm just going to go over everything one more time. I just don't have the experience troubleshooting this kind of thing so I'm not positive what to make of the information I'm finding.

One thing I did notice was when I raised the main jet needle, the hesitation started earlier. It went from being at about 6000-7000 rpms to 5000-6000 rpms. However, until I hit that range, the bike runs like crazy now that the needle has been raised.

I'm going to try a WOT plug chop tomorrow if I get a chance, but I'm betting it just tells me that I'm not getting enough fuel at WOT (and not necessarily because of main size).

DoubleDub wrote:

...Any other suggestions....

If not already done, would assure valve clearances being to specs.

And double check ignition timing by dynamic method with strobe light, also assuring proper function of the advancer by watching it instantly move back and forth as rpm's are varied by blipping the throttle.

Would also remove the sparkplugs and look for fat blue sparks.

Am not so sure the jet needle clip position should be different than middle position.

Probably could use a good plug reading immediately after throttle chop with simultaneous ignition kill and clutch disengagement (squeeze the lever and keep it squeezed) while coasting to a stop. Good to carry a short length of tubing that fits snugly around spark plug to remove the plug without burning fingers.

Good Luck!

larrycavan wrote:

Make sure you check the design fuel level in the carbs. If it's off, you'll play hell trying to jet the bike properly.

I don't recall any 1015cc with 26mm carb and 115 Main Jets from the factory??? :huh: [maybe 76 900 LTD was that rich]I'd have to dig for my old Kawasaki spec manual to see.

US Spec 1000's generally had much smaller main jets. From 107.5 down to 102.5

The factory continually leand out the Z motors over the lifetime of it's use with 28 & 26mm VM type carbs.

Your setup with the replacement filter and airbox silencer removed is a good setup.

If you do have a fuel stavation problem, after correcting that, your bike may well like a smaller main jet. Only 1 way to tell....

Larry - just wanted to follow up. I just wanted to say thanks for your jetting recommendations. I left them at stock for now which is slightly richer than what you were recommending and it's running great!

Thanks again!