KZ650 carbs

I have a '77 KZ650 that I thought about cleaning the carbs on.
However, I'm confused as to just what I have.
I can only find one adjustment needle, that would be on the
bottom, which should be the idle. I have seen diagrams showing
several needles, but my carbs don't seem to have those.
I have also seen that in the 80's they capped them off, but I
don't think mine are capped that I can tell.

I have pictures of my carbs at:

http://users.dls.net/~reed/carb_left.jpg
http://users.dls.net/~reed/carb_right.jpg

Several years ago, I took them apart and soaked them. No difference.
They work fine when opened up some (say over 2000 rpm) but aren't very
good at idle. I usually have to play with the choke, and even after
warmed up it wants to stumble. I've had it since 1978, and it's always
been cold natured, but it seems a little worse now, and is a pain
as I'm driving it more now Sometimes in the morning, I can get down
to the end of the road, but there just isn't any power to take off.
Once I take off, I'm on the interstate and it runs fine at higher RPM.

Is it worth taking apart and cleaning? Would it be O-rings need replaced,
the needles cleaned and adjusted? I also want to sync them, but don't know
if that would take care of this problem.

So I'm not sure just what adjustments or needles I have, as I see conflicting
info between diagrams I see and my carbs. I'd just like to figure out what
adjustments there are and try and get them running better.

I don't mind taking them apart, although it isn't the easiest to do, but
don't want to do work not necessary. Also, is there a good place to get
a kit? I would assume I should change all the O-rings and gaskets
while I am in there.

 

Your carbs will have the idle mixture adjustment screws coming up from
the bottom or the ones on the sides of the carbs, not both. I suppose
the ones coming up from underneath adjust fuel and air that are
already mixed, so turning the screws counterclockwise will richen the
mixture.

If you can see the slotted head of the screw, they aren't capped off.

That generally indicates lean idle mixture. You may have to take the
carbs off and spray an aerosol cleaner like Berryman B-12, STP, or
GumOut through all the orifices.

Those carburetors don't have chokes. They have starting enricheners.
When you move the starter plunger, it acts like a tiny carburetor
built into the side of each real carburetor. If the throttle slides
are open too far, the starting enrichener doesn't work right.

Turn the idle mixture screws all the way clockwise, counting the
number of turns. Write the number of turns down for each carburetor.
Then remove the screws and spray carburetor cleaner down the holes
they came out of.

When you reinstall each screw, turn it all the way clockwise, then
back it off the same number of turns that you wrote down before you
removed the screw. You will be within 1/4 of a turn of the factory
adjustment.

Newbies have an awful time getting idle mixture screws set right. They
expect the idle speed to keep increasing as they turn the idle screws
further and further counter clockwise.

When they turn the screws too far, the mixture gets too rich and the
idle speed slows down to the ragged edge of stalling.

So they turn up the master idle knob. Later on, when the engine is up
to operating temperature it idles far too fast, so the owner turns the
master idle speed down and the engine stalls again.

This confuses the heck out of the owner who doesn't know about the
transition ports just downstream of the throttle slides. The
transition ports supply extra fuel at small throttle openings when
you're trying to smoothly accelerate away from a stop.

If the engine idles too slow when you start it up, don't yield to the
temptation to increase the idle speed, turn each idle mixture screw
clockwise about 1/8th of a turn to see if the idle speed picks up
again.

It's a pain in the butt synchronizing that type of carb, and
motorcycle shops make a lot of money synchronizing carburetors when
the real problem is gum and varnish buildup inside the orifices and
passages.

After the dealer synchronizes the carbs, the owner goes for a long
ride and the alcohol additives in the fresh gasoline clean the carbs
out while the owner rides. Then the carbs are out of synch again
because more gasoline is flowing through the idle jets. �

Like I said, you have one type of idle mixture screw or the other or
the other, not both. �

Try www.oldbikebarn.com. You can get four kits for about $100.

Why replace stuff that isn't worn out?

 

Your carbs will have the idle mixture adjustment screws coming up from
the bottom or the ones on the sides of the carbs, not both. I suppose
the ones coming up from underneath adjust fuel and air that are
already mixed, so turning the screws counterclockwise will richen the
mixture.

If you can see the slotted head of the screw, they aren't capped off.

That generally indicates lean idle mixture. You may have to take the
carbs off and spray an aerosol cleaner like Berryman B-12, STP, or
GumOut through all the orifices.

Those carburetors don't have chokes. They have starting enricheners.
When you move the starter plunger, it acts like a tiny carburetor
built into the side of each real carburetor. If the throttle slides
are open too far, the starting enrichener doesn't work right.

Turn the idle mixture screws all the way clockwise, counting the
number of turns. Write the number of turns down for each carburetor.
Then remove the screws and spray carburetor cleaner down the holes
they came out of.

When you reinstall each screw, turn it all the way clockwise, then
back it off the same number of turns that you wrote down before you
removed the screw. You will be within 1/4 of a turn of the factory
adjustment.

Newbies have an awful time getting idle mixture screws set right. They
expect the idle speed to keep increasing as they turn the idle screws
further and further counter clockwise.

When they turn the screws too far, the mixture gets too rich and the
idle speed slows down to the ragged edge of stalling.

So they turn up the master idle knob. Later on, when the engine is up
to operating temperature it idles far too fast, so the owner turns the
master idle speed down and the engine stalls again.

This confuses the heck out of the owner who doesn't know about the
transition ports just downstream of the throttle slides. The
transition ports supply extra fuel at small throttle openings when
you're trying to smoothly accelerate away from a stop.

If the engine idles too slow when you start it up, don't yield to the
temptation to increase the idle speed, turn each idle mixture screw
clockwise about 1/8th of a turn to see if the idle speed picks up
again.

It's a pain in the butt synchronizing that type of carb, and
motorcycle shops make a lot of money synchronizing carburetors when
the real problem is gum and varnish buildup inside the orifices and
passages.

After the dealer synchronizes the carbs, the owner goes for a long
ride and the alcohol additives in the fresh gasoline clean the carbs
out while the owner rides. Then the carbs are out of synch again
because more gasoline is flowing through the idle jets. �

Like I said, you have one type of idle mixture screw or the other or
the other, not both. �

Try www.oldbikebarn.com. You can get four kits for about $100.

Why replace stuff that isn't worn out?

 

Your carbs will have the idle mixture adjustment screws coming up from
the bottom or the ones on the sides of the carbs, not both. I suppose
the ones coming up from underneath adjust fuel and air that are
already mixed, so turning the screws counterclockwise will richen the
mixture.

If you can see the slotted head of the screw, they aren't capped off.

That generally indicates lean idle mixture. You may have to take the
carbs off and spray an aerosol cleaner like Berryman B-12, STP, or
GumOut through all the orifices.

Those carburetors don't have chokes. They have starting enricheners.
When you move the starter plunger, it acts like a tiny carburetor
built into the side of each real carburetor. If the throttle slides
are open too far, the starting enrichener doesn't work right.

Turn the idle mixture screws all the way clockwise, counting the
number of turns. Write the number of turns down for each carburetor.
Then remove the screws and spray carburetor cleaner down the holes
they came out of.

When you reinstall each screw, turn it all the way clockwise, then
back it off the same number of turns that you wrote down before you
removed the screw. You will be within 1/4 of a turn of the factory
adjustment.

Newbies have an awful time getting idle mixture screws set right. They
expect the idle speed to keep increasing as they turn the idle screws
further and further counter clockwise.

When they turn the screws too far, the mixture gets too rich and the
idle speed slows down to the ragged edge of stalling.

So they turn up the master idle knob. Later on, when the engine is up
to operating temperature it idles far too fast, so the owner turns the
master idle speed down and the engine stalls again.

This confuses the heck out of the owner who doesn't know about the
transition ports just downstream of the throttle slides. The
transition ports supply extra fuel at small throttle openings when
you're trying to smoothly accelerate away from a stop.

If the engine idles too slow when you start it up, don't yield to the
temptation to increase the idle speed, turn each idle mixture screw
clockwise about 1/8th of a turn to see if the idle speed picks up
again.

It's a pain in the butt synchronizing that type of carb, and
motorcycle shops make a lot of money synchronizing carburetors when
the real problem is gum and varnish buildup inside the orifices and
passages.

After the dealer synchronizes the carbs, the owner goes for a long
ride and the alcohol additives in the fresh gasoline clean the carbs
out while the owner rides. Then the carbs are out of synch again
because more gasoline is flowing through the idle jets. �

Like I said, you have one type of idle mixture screw or the other or
the other, not both. �

Try www.oldbikebarn.com. You can get four kits for about $100.

Why replace stuff that isn't worn out?

 

There's some nightmare involving early Z650 carbs and needles that were
fixed, but which broke off, causing rough running. Kawasaki quietly
changed the design, and changed the carbs under warranty for any riders
who complained.

Now I'm not sure of the exact type of carb affected because they're
outwardly identical to the replacements, but I've recently been
researching this for Classic Bike in the UK. It strikes me this could be
your problem, in which case replacement carbs are the only answer.

If your bike is a B1 (caliper mounted forward of the fork leg) then a
pound to a penny this is the issue.

Itr's a real odd one.

 

Because it might be near the end of its service life?

 

If it ain't worn out, don't replace it. If it ain't broke, don't fix
it.

Sometimes a mechanically unsophicated newbie can notice obviously
broken parts.

But they often have no way of knowing which parts are expected to wear
out and which parts are damaged by abnormal wear.

They really have little understanding of what they are looking at, and
shop manuals aren't much help either,
as they are often written by mechanically naive desk jockeys.

So, when a newbie sees that he can buy a carburetor kit, he hopes that
installing every item in the kit will somehow magically cure a
carburetor problem that he really doesn't understand anyway.

I was 18 years old and I was assigned the task of installing new
brushes in an electric motor driven AC generator which was called an
"inverter" in the days before solid state electronic boxes that
performed the task with no moving parts.

I drew an overhaul kit out of stores, and I thought I was
doing "a good thing" by installing every part in the kit into the
inverter.

The tech sergeant in charge of the shop came around and asked what the
hell I thought I was doing.

I told the sergeant that I felt that I should use the whole kit, since
I had it right there. The sergeant told me to just install the god
damned brushes and throw thr rest of the kit into the trash can.

I couldn't argue with his logic.

 

Oh, get fucking real. If you're pulling carbs apart, and O-rings and
gaskets are pennies (which they are), you might as well replace them.
It's a false economy not to, especially if they're thirty fucking years
old.

I mean, let's say you pull an engine down at 40-50k miles for new rings
or whatever. Are you going to put it back together again without
spending another few bucks on a camchain and a tensioner blade? Rings
good for another 40-50k, and camchain good for maybe 10k? It's just
common sense.

<Snip irrelevant bollocks>

 

There is no reason to buy a carburetor kit that contains all sorts of
unnecessary parts and put those parts into the carbs to replace parts
that don't need replacing. Carburetor kits are about $25 USD each,
plus shipping, so the OP would have to buy four kits, hoping they will
be a magical cure for what ails his motorbike. Right now, he knows so
little about his carbs, he doesn't know what he needs, he's just
hoping somebody will tell him that $100 USD worth of parts will fix
his problem.

And my answer is, if it ain't broke (or worn out), don't replace it.

(snip irrelevant bollocks)

 

Once more you've tried to steer off the point.

It's not a matter of buying the kits to cure his problem, though, is it?

It's a matter of replacing *very* old perishable components (gaskets and
O-rings) as part of a general overhaul. And you seem to be the only
person who thinks this is a bad idea.

No mention of complete kits. You've just thrown this in to distort the
point to "support" your argument.

O-rings cost pennies, and carb gaskets can be made from gasket sheet,
again for pennies.

You really do dispense some appalling "advice" from time to time. To
time.

 

For parts, a good first place to look is http://www.z1enterprises.com and
if Jeff doesn't have it and you need OEM parts, I've had good luck with
http://www.ronayers.com You can put in the Kawasaki part number in the
search box and get a price that will beat your dealer or Bike Bandit.

Another source for carb help is http://www.wgcarbs.com/ and
http://www.kzrider.com for all sorts of info.

Best of luck,

- Nate >>

 

Yes, the OP did ask about the availability of overhaul kits in his
original message. Like most naive newbies, he guesses that a
carburetor kit might be a magical solution to a carburetor problem
that he doesn't understand.

As I mentioned before, complete aftermarket kits contain many parts
which may not even been needed, but he won't know exactly what he
needs until he gets the carbs off the engine and strips them down.

Even then, it takes experience to know what is worn out and what is
perfectly OK.

No evidence has been offered that there is anything wrong with any
gasket or o-ring in the carburetors, which are still installed.

Again, go back to the original post.

If it ain't broke, don't "fix" it.

What is so "appalling" about saving a newbie $100+ USD?

 

OK, I interpreted "kit" as being something separate from the O-rings
and gaskets.

It's not fixing. It's a sensible precautionary measure as he is
contemplating stripping down something that's 30 years old. And again,
you're the only person who seems to think that re-using 30 year-old O-
rings and gaskets is a good idea. You wouldn't re-use old gaskets if
you tore down an engine. You wouldn't do a top-end rebuild without
replacing oil seals. This *no* different.

The fact that it doesn't cost that to do it, you numbskull.

 

Hey, an Englishman should know that a "kit" is a collection of parts
or tools that goes far beyond immediate needs.

"Kit" comes from the Middle English "kyt", which comes from the Middle
Dutch "kitte" which was a barrel made
of staves wrapped with hoops. Butter and fish and pickles, etc, could
be carried off to market and then sold right out of the "kyt".

Invariably "kyts" found other uses, like tinkers would
carry their tools and materials around in wooden buckets called
"kyts", and nowadays modern plumbers use old 5-gallon plastic paint
buckets to carry their tools and repair parts into your house so they
can muck about under the kitchen sink.

And there is even more of the plumber's "kyt" outside in his van, just
in case the part he needs to fix your plumbing isn't in his bucket.

You wouldn't want to pay for the cost of the plumber's entire "kit",
but he's going to try to sell you parts you don't need, claiming that
it will save you money in the future.

But your money goes into the plumber's immediate bank account and you
don't get to take that vacation you'd planned on...

So, by now you should be realizing that a carburetor "kit" will
contain far more parts than the OP may ever need.

The OP is not talking about overhauling an engine. He's
wondering if a carburetor kit will fix his mysterious problem. And I
say, "if it ain't broke, don't fix it, if it ain't worn out, don't
replace it."

And, it would be a really good idea for the OP to study
some carburetor webpages to find out just what does wear out on a
carburetor.

When I can't feel my nose and eyebrows, I go home...

 

Working on 10 to 20 year old atv's, we found that it was often much
more productive to simply spend the money on a new "needle and jet
set" for the carbs, instead of a "kit".
If we needed replacement small parts, we would often use an
aftermarket rebuild kit, but these kits often did not contain a needle
and jet set which was identical to the original that came in the carb
(which was worn out and causing the problem for the customer's atv).

Likewise with carburetor diaphragms (that work the slide). I only
used the OEM items for these.

I would always replace anything that was worn in the carbs. It is
just not always needed to replace the sealing o-ring and washers,
which is mostly what the kits contain that are the same as OEM.



Wudsracer/Jim Cook
Smackover Racing
'06 Gas Gas DE300
'82 Husqvarna XC250
Team LAGNAF

 

There are pictures of damaged jet needles and worn out needle jets on
the www.factorypro.com website.

Needle jets in semi-downdraft carburetors will be worn oval within
5000 miles. It's amazing that the designers didn't forsee the
likelihood of this happening when the jet needle lays right on the
needle jet in the downdraft carbs...

 

NRP Carburettors in the UK produces pattern items to amazing
standards, for about half the OE cost. No idea if there's an quivalent
in the US.

No, not always. But on a 30 year-old bike, with 30 year-old seals and
gaskets in the carbs, if you're pulling the carbs down, it's a
sensible precaution, given that it's easy and costs very little. Which
is precisely my point.

 

If you have an URL, then post it. Maybe they will ship across the
pond.

Yeah, well, you've never bought anything in a Kawasaki
$tealer$hip in the USA, where a tail light lens can cost $200 USD, and
the two rubber parts necessary to rebuild a leaking petcock would cost
$20 USD---*if*
the goofball behind the parts counter could figure out
the parts numbering system.

 

http://www.nrp-carbs.co.uk/

And they do.

New website, stll under construction, I see.

 

Also, in my experience Ron Ayers gives far, far better service than
parts bandit. I went round & round with parts bandit once trying to
figure out which number was the SV-650S clutch perch (no mirror mount)
and which was the naked SV (with mirror mount) and in the end they still
sent me the wrong one. I then had to got through their lovey return
system.

-gc