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30 Posts
Discussion Starter #1
I have a 1990 750 and I need to clean the carbs. they have a bunch of gunk in them and causing alot of problems. How do I get those puppies out. I removed the air boots and rubber lines. I loosened the boots on the inside and it wouldn't move much. I am scared to break something since I have never dont it before. Helppppppppppppppppp!!!!!!!!!!!!!!!!!!!!!1:beerchug:

Premium Member
3,505 Posts
This may scare you more, but two more things need to go: first, you should pull the right side (sitting on the bike) coolant pipe that comes up off the cylinder head and also move the upper coolant hose outta the way. You'll want to drain some radiator fluid to do that, but a "clean catch" as the nurses say is good - you can put it right back in when you're done if all looks ok.
Second - deep breath - pull all the connections for the upper (headlight, ignition, etc.) wiriing harness and get that out of the way (i.e., pull the harness out from between the frame and the airbox). Then you can hit the airbox with some lube, pull it out, and free up a whole lot of space for yourself. It can be done without pulling the airbox, but that sure makes it easier. And if it's any consolation, all the wires are either color-coded or are in x-pin connectors - you can't go wrong.

If you're just having trouble getting the carbs to come up outta the boots, try hitting the boots themselves with a hair dryer, and then see if you can pry them up gently with a flat screwdriver or similar tool. The boots that connect the carbs to the engine block are pretty sturdy - they can handle a little prying. Also, the manual tells you to "keep the front boot on the engine block, take the rear one with you when you pull the carbs." My experience has been - take whatever comes with you, even if you have to reinstall the front boot. Just a whole lot easier.

If it's any consolation, these carbs are an absolute pain in the behonkus, so you're not alone! Good luck, young Jedi!

Undercover Sportbiker
1,097 Posts
Since you're gonna have em off, go ahead and do the shave! Seriously, life is SO much better with no air box. But I'm biased. The carbs are still smoething of a pain to remove, but nowhere near as bad as when the airbox was still on. Your baby can take a fair amount of pulling / prodding. Don't be afraid to muscle it when you have to. Just make sure everything's disconnected before you yank. Nothing like pulling the choke cable apart casue you left it connected..... Um, I have a friend who did that, and um.........

1,750 Posts
Now someone needs to design a manifold so we can mount one Mikuni on our beasts.


30 Posts
Discussion Starter #5
Shave? What is this(obviously has to do with the air box) and how does it help?

Search Goddess
2,002 Posts
Some info from the yahoo group regarding ear shaves

Here's some valuable information that I have collected regarding the Ear Shave.
This should get you started, but may require some more research.
Please note that I am not a mechanic. This is information only. If you're
unsure, have a pro do it. Feel free to email me or post any q's.

Thanks to Jason Spivy for posting the parts list.

Ron Ayers:
1 x 14-20900 EMGO crank case filters* = $10.63
(this one mounts on the left side and connects to the crankcase
or you can order one more for the right side, connects to the
breather on the carb float bowl assebly)
Shipping = about $8.00 from California
*There has been problems with the adhesive on these filters,
most of us who have them used a stronger silicone or epoxy.

Auto Zone
1 x Spectre 3995 Breather Filter $9.00
(this one is used for the breather on the carb float bowl and
can be placed underneath & behind the seat)

2 x 019-812 40-Idle jet = $8.90
1 x 019-194 140-Main jet = $4.45 (2-140's seems to work for most)
1 x 019-195 142-Main jet = $4.45 (optional)
1 x 009-396 0.126" Shim 12 pack = $4.00
Shipping = about $8.75

Auto Zone (may have to special order)
2 x K&N RC-2340 = $71.82 (not including local tax)
AJ USA (www.ajusa.com) 1-800-877-1911
2 x K&N RC-2340 = $58.70 (includes "FREE" shipping!!)

1 x 1/4" rubber vacuum cap $1.59 (Autozone comes in pkg of 4)
(Used on right side of carb vacuum fitting)

Small cable tie (for the vacuum cap)

True Value: (optional)
2 x 20mm chrome bolts = $6.38
2 x chrome washers = $1.78
(non-chrome bolts and washers about $ .75)

Total = about $135.00

In case I made a typo, verify parts numbers before ordering.

The chrome bolts and washers were used to mount the crank case filters
(stock bolts were too short). One filter was used for the crank case
and the other for the carb breather hose. There are cheaper filters
than K&N but that is a personal preference.

You'll also need a new breather hose which can be bought at any auto
store. I used some hoses laying around here but it looks like you need
the hose, 45 elbow, and 90 elbow.

To answer several questions in one post:

Q: Why do you add shims?
A: After the ear shave, the needles need to be shorter.
As far as I can tell, no one makes a shorter needle for these carbs.
You may have read some other members posts about Sherm's rebuild
kit that includes replacement needles. I used the stock needles.
The only way to shorten the stock needles are to add shims
(obviously doesn't shorten it but raises it up a little).

Q: How many shims did you use on each needle?
A: I put two under each needle and that seems to work fine.
Two shims seems to be the standard that works for most people.

<This is assuming that you are using the original stock needles.>

The following is part of a discussion regarding the stock
needles -vs- the needles that are supplied with The Factory Pro
Jet Kit from Sherm's:

Just to clarify -- I used 4 shims ON "TOP OF" each
needle, not under. -Pick

The shims go "UNDER" the head of the needle (like the head of a nail).

If someone said that they put a washer under a nail, it would most
likely be understood that the nail went "through" the washer, not that
the point of the nail was on top of the washer.

The needle is tapered, and with more air flow from the ear shave, more
fuel is needed to maintain the correct fuel to air mixture, so raising
the needle opens more area around the needle to flow more fuel.
I removed each needle, slid two spacers on, then put the needles back
in. This puts the spacers on the top end on the needle but not on top
of the needle. ??? I'm confused. What does putting spacers on top of
the needle do?-doowriter123

OK, I don't claim to know the whys and wherefores, but I got the ear shave
kit from Sherm's before they went out of business. I got a selection of
jets, shims, and new needles with the kit. I used 40 pilots and 140 mains,
with the clip in the 3rd position on the new needles. IIRC, that was in the
middle slot. I did not use any shims. The bike ran fine while
accelerating, but when I let off the throttle, it would stumble badly --
sort of like it was running out of gas or something (maybe it was
flooding?). I popped the tops off of the carbs and put 4 shims on top of
each needle, and the stumbling disappeared. The bike ran great all the
time, throughout the rpm range, accelerating or decelerating. I don't know
why this worked for me. It didn't make any sense to me either. I thought
the shims would have to go under the needles. I can only guess that putting
the shims on top causes more pressure to be applied downward, keeping the
needles from "floating" as much, or something like that. -Pick

Sooooo.... You didn't use the original needles. You had needles that
used clips that came with Sherms kit. The clip position limits the maximum
down limit of the needle. This explains the 3rd clip position.

If the clip on the needle is enough smaller than the vacuum slide
spring seat, the needle could possibly be able to wiggle around and
up and down, so putting shims on top could hold the needles down
where they should be.

The needles and clips are a more expensive way to get the result,
but they may have been chosen because of their profile. -doowriter123

That sounds plausible to me. The new needles came with the Factory Pro jet
kit, so I thought I may as well use them. If I had stayed with the stock
needles, I would most likely have used a different configuration to get it
to run right. -Pick

After the ear shave, the needles need to be shorter.
As far as I can tell, no one makes a shorter needle for these carbs.
The only way to shorten the needle is to add shims
(obviously doesn't shorten it but raises it up a little).

Use the stock needle, and two shims "UNDER" each needle. -Frank Braun

Q: My new jets seem shorter than the stock jets, is that okay?
A: The jets that come with the PRO Jet Kit are the same length
as the stock jets. The jets from Sudco seem to be shorter but
have the same effect. So length does not seem to be an issue.

Q: you mention bolts to mount the crank case & breather filters. Where
did you mount these?
A: I mounted them at the top bolt hole from the ears. (Some have
mounted to the bottom bolt hole) The old bolts
were too short so they had to be replaced.

Q: Whats the vacuum cap for?
A: The carbs have two vacuum connectors. One goes to the gas tank
petcock and the other one used to go to the surge tank. I decided to
plug the vacuum on the right side of the bike and secure it with the cable
tie. The engine seemed to idle better. Some people buy a small filter
and connect it under the seat. It's optional.

Q: did you take carbs out or do the needle & jet work with them in place?
A: I installed the shims with the carbs in place. I did everything I
could to install the jets without removing the carbs but couldn't do
it. Removing the carbs was easier than I expected. Plus it gave me a
chance to inspect the diaphrams and the connections.

Q: what is wrong with the ears ? why remove them ?
A: There's nothing wrong with them*. Some want to increase air flow in
order to increase power (and decrease fuel economy*). Others want a
cleaner, less cluttered appearance. I had one ear busted and needed to
replace it. Also, it seems that every time I did work on the bike, I
was hitting the ears with my elbow, head, etc. I don't mind the look of
the ears, but I do enjoy having less stuff in my way.

*Keep in mind that the ear shave may be illegal in some states due to the emmissions.
Save all the old parts just in case the laws change.

A great set of instructions from Trent Mills (as well as other info) can be found in the VROC archives
(search on 750 ear shave)


85 VN 700
1,033 Posts
I shaved and I'm glad I did. Do keep in mind though that if you live in an emissions state (I.E. need to get an inspection sticker) that you'll have issues on inspection day (unless you pull the airbox out the way cindy said, a shave is pretty much permanent.

Premium Member
2,850 Posts
I have a 1990 750 and I need to clean the carbs. they have a bunch of gunk in them and causing alot of problems. How do I get those puppies out. I removed the air boots and rubber lines. I loosened the boots on the inside and it wouldn't move much. I am scared to break something since I have never dont it before. Helppppppppppppppppp!!!!!!!!!!!!!!!!!!!!!1:beerchug:
Do you have a rebuild or repair kit for them for when you put them back together?

If so, where the heck did you get it from?

I need to do this to my bike too, but was trying to get most of the parts lined up first.

Are you just going to reassemble them with the same gaskets and seals they have in them now?

30 Posts
Discussion Starter #11
I don't have anything for it. I am just simply trying to clean it to get it running.
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