TOPIC:

Recently purchased a KZ1000 B2. I'm working my way through all the obvious checks. Right now, I've got the carbs off for a thorough cleaning.

Before removing the fuel mixture screws, I checked to see how they were set. Each was set differently as follows:

Carb 1: 1 1/4 turns
Carb 2: 2 1/4 turns
Carb 3: 2 1/4 turns
Carb 4: 2 5/8 turns

Is it normal for each carb to be set differently, or should they all be set the same? Why would they be adjusted differently?

Is 2 1/4 turns the factory setting for stock carbs on this model?

If you didn't have plastic limter caps on the end of the screws, someone has changed the settings from what the factory initially set them to. The original carbs had 1/4 turn limiter caps on the screw ends and you seldom see those things on the caps since most carbs have had the mix screws reset MANY times. The 78 carbs are typically as lean as lean can be... #15 pilot jets. If you try and start a 78, you will note that they are a bit fussy to start and take a long time to warm and backfire some when decelerating.

Does the bike have the factory airbox and pipes? What is the current jetting set up? Pilot jets? Main jets? Jet needle clip position? Once you figure out how that has been changed, I might be able to take a stab at how to set the mix screw settings. I will say that there shouldn't be that much difference between settings generally such as what you noted.

Thanks George.

Yeah, I was wondering why I didn't see any limiter caps, as described in the service manual.

To answer your questions, I have stock airbox and 4-2 stock exhaust. Main jet is 102.5 and pilot is 15. I'm at my office now, so I'm not positive on those numbers, but I think that is correct. Needles are clipped at the #4 position (2nd up from the "pointy" end).

What changes would you suggest?

Thanks again.

Post edited by: Skyman, at: 2006/11/30 15:53

Sounds like stock jetting except for the jet needle clip positions... they are numbered from top to bottom where top slot is #1 and second is #2... bottom slot is #5. If yours are on the 2nd slot, then I suggest you have a look at my web site. Check the coil repowering mod and the valve clearance link. Your plugs are VERY likely to be fouling quickly; most likel due to one of these reasons. Once you check valves and coil power, and have done an ignition tune up, you might want to spring for new carb holders and a new air cleaner. Once that is done, swap pilot jets to #17.5 and turn mixture screws 1.5 turns out from VERY LIGHTLY seated (tips break off EASILY if you tighten screws). One size up on main jets is also helpful even with stock airbox and 4 into 2 exhaust... you could even go to #107.5 mains and do no harm. Also at that time, reclip jet needle to 3rd slot because once you get plug sooting issues cleared up, your mid-range will prove slightly lean with the needles clipped to the 2nd position. Once you get this stuff done, the bike should run quite a bit cleaner and have better performance. Also adjust your cam chain tension as part of the overall tune up process and remove and clean/lube your mechanical ignition advance (under points cover).

WG, Thanks for your suggestions.

Yes, the coil repower mod is definitely in the plans. I did this on my KZ440 after reading your article, and it worked well.

I will bump up my jet sizes too, per your suggestion.

One question though. I think you may have misunderstood my description of the current needle clip position. They are currently on the #4 slot from the top. Not #2 (I meant that they were on the second from the "pointy end" (bottom)).

So when you wrote that I should move them to #3, were you thinking I had them on #2 from the top now? They're on #4. Should I leave them there?

Thanks again.

I guess I did misread what you said initially. You are on 4th slot. 3rd is likely about right but if you are not having problems with midrange being a bit rich after changing the jets, just let it be. Every time you reclip the jet needles you really should resync the carbs.