last chance before I blow it! Rejet '78 kz1000

I can't afford to buy a new bank of carbs as someone suggested, so I'll rejet the stock '78 kz1000 carbs, which are "VM 26mm" Mikunis.

The stock jets are:
1) pilot jet: 15
2) main jet: 105
3) needle clip position: 3

The prior owner did engine and exhaust mods:
- Kerker 4-into-1 with a street (not race) baffle
- removed rearmost part of stock air intake, but the stock air filter and boots are still there
- bored out to 1137cc
- put in 'hotter' cams
- electronic ignition

I'm changing the jets to this:
1) pilot jet: 20
2) main jet: 120
3) needle clip position: 4 (this raises the needle upward)

So before I do the jet change -- any advice?
I have to make this work with stock carbs.

After all, the prior owner put 12,000 miles on the
bike *after* all the exhaust/1137cc/cams/ignition modifications above with *no* changes in jetting! What ever I do will be an improvement.

What I'm looking for is advice on the jet #'s above.
Are those the best choices?

117.5 + 17.5 are just a *smidgen* lean for me. 3rd clip.

Jardin 4:1 & pods BTW. Exhaust ports polished, fresh valve job, new rings.

1978 KZ1000 LTD

depending on your elevation is how you should jet your carbs with a 1075 and stock 26 carbs i use 117.5 mains and 17 pilots i put the clip in the 4th position and it wrks fine by the way i'm at around 2500 feet above sea level.

Thanks BeatPoet, and thanks timebomb33, forgot to mention that I'm at sea level.

I guess my intuition was correct about switching from 15 pilots and 105 mains (stock) to the #20 pilots, #120 main jets and 4th position for the needle's clip -- I will need to be slighty richer than what both of you recommended (17 pilots and 117.5 mains) because I'm flat at sea level here in Silicon Valley.

Okay, I'm going for it, 30 seconds ago FedEx delivered my 4 new sets of gaskets/O-rings/needles for the carbs!

I'll post soon with the results!

at sea level that combo should work pretty good for you.good luck and have a lot of fun with it.

You did not tell us what size or kind, the cams are?

I would like to help you! I don't know if I can, without sounding like a grumpy old fart. Sorry if I do!

How much air can my lungs hold? How much air do your lungs hold? How much air does my body need? How much air does your body need?

Are we the same?

Does that sound silly to you? I bet you couldn't guess if your life, was dependent on it!

It's the same thing with a motor, each one is different. We can all take a guess, but that's it. We might not be able to put you in the ball park, perhaps we can get you close to the ball park.

Most people can ride a bike and most can build one. Motor tuning is a real skill and a lot of people just can't do it. Give yourself time to learn, ask alot of questions and most of all, be a good listener. (with one or two answers, you are ready to go for it)

I am sorry, but you don't have a complete question yet! Cams are a big deal, what kind of head work, do you have? Are those smog carbs?

I live at 272' above sea level. This is the combo that our local kawasaki shop installs. They have done this since the kz1000, came to the show room floor: Stock motor, stock air box, stock carbs, stock baffle with packing.

#17.5 pilot jet
#117.5 main jet
needles raised one notch.

They have used this for many many years. Each bike is check on the exhaust machine and then ridden.

For me, myself, and I, this is to lean, for a stock bike that is ridden very hard, for long periods of time. I add a touch to it.

Now you have a 1137 w/cams and want to run almost, the same jets???????

I will suggest a starting point, for you. (just a starting point!)

#17.5 pilot jet
#122.5 - #125 main jet
needles raised one notch.

Be gentle, until you get a handle, on it! The old jetting may have worked for someone else, doesn't mean it will work for you.........take care!

I don't know what cams the elderly prior owner put in it, and his recollection is not there either. He just said "I put hotter cams in it."

I'm not a cam guy. I may pop the valve cover to check for markings on the cams, but the idea of then having to sleuth around and ask things like "the cams look like this, the cams have these numbers/letters engraved on them, what cams are they", etc. is not something I want to do. I'm not at all sure I even need to, since he drove it for 10 years in this condition.

I'm going by the following facts:

1) bike has stock jets (15 pilot, 105 mains, stock needle setting)

2) and it ran fine for this guy for more than 10 years after he put on the 4-into-1, the 1137cc kit, the cams, and the electronic ignition.

3) was he getting max horsepower? I *doubt* it, what with being at sea level here and all stock jetting with all the engine mods.

So to start with, I'm simply going to rejet and dial in the tuning that way.

Let me say this a different way: if the old guy had said "You know, I just put in hotter cams, bored it out to 1137cc, put on the Kerker pipe and the electronic ignition then rode it around the block, here the bike's yours now" -- I would tend to be a bit more cautious.

But he put 12,000 highway miles on it driving it a short distance (he said 4-5 miles round trip on the 101 freeway) back and forth to his workplace each day for 10 years with all those mods and the stock jetting.
Was he running it lean? I think so. But I'm going to switch to bigger jets, and I suspect I'll be messing around with the carb jetting to get it so
the plugs look right etc.

You may well be right about the 125 mains etc. --
I'll let you guys know what I find.