How to strip and clean your carbs

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banner001
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How to strip and clean your carbs

Post by banner001 » Thu Aug 09, 2012 7:08 pm

Stripping ZXR 400 L-model 32mm carbs a quick guide.

Time depends on how clean the carbs are, mine took me in total about 8 hours to do all 4, although this included all the sonication steps to clean everything. If you are just changing jets and needles expect ~15 minutes per carb to strip and the same to assemble.

Ok tools you will need:-
phillips screwdriver
thin screwdriver
pliers with a covering over the tips
3mm (i think) allen key
8mm (i think) socket/spanner

Dissassembly
First thing, check your carb internal diameter, they come in 30mm and 32mm versions, according to RedexRobB 30mm gives better midrange, 32mm gives better top end. These are 32mm:-
Image

Ok mine came with the velocity stacks already removed, you will need to remove these and the plate on top to give:-
Image

Now remove the (i think) vacuum cover, 4-screws:-
Image

Take off the cover and remove the spring and the orange plastic bit:-
Image

You can then take out the rubber slide holder/seal along with the jet needle, check the rubber boot for tearing/warping etc and replace if needed:-
Image

Carefully remove the jet needle, you will have a small clip on one of the grooves and possible some small shims on top. I have 6 grooves, my clip is on #4 (from the top) and i have 3 shims on the needle. These were taken from a ram-air dynojetted race bike so DO NOT USE ANY OF THESE SETTINGS AS STOCK SETTINGS! Yes i know my nails need clipping and my cuticles are a mess girlfriend :smt008 :-
Image

Clean!:-
Image

Next, flip the carb over and remove the 4 screws holding in the back of the fuel cover:-
Image

Clean it! Also remove the fuel drain screw (allen key) and clean around there as well:-
Image

Remove the screw in the top-right corner to free the orange fuel float:-
Image

Then you can remove the assembly:-
Image

Check the black plastic bit for damage, its what regulates fuel flow into the carb, if damaged replace:-
Image

Remove the screw in the top-middle by the brass bit to gain access to another smaller fuel filter:-
Image

Use your covered pliers to remove it:-
Image

Onto the jets! This is the pilot jet, remove and clean:-
Image

This comes in 2 parts, use a screw driver to remove the main jet, then use a socket/spanner to remove the brass bit that the main jet screws into. This brass tube is the needle jet holder...clean everything!:-
Image

This is the pilot air screw, remove and clean. Once removed there should be 4 parts in this order, Screw - Spring - Metal ring - O-ring, make a note of how much this has been "screwed out" from fully screwed in. Manual states anything from 1.5 turns out to 2.5 turns out, turning it out richens the mixture:-
Image

Put it all back together and it should be spanking clean like this:-
Image

Put back on bike and give it a test with your new clean carbs!

I am not going to cover carb-tuning here, that will be for another guide.

One final point, i mentioned sonication, i used a sonication bath at work to clean everything. Brass/pure metal things can be cleaned in 100% acetone/carb cleaner, if you can get some heat in there do so, and sonicate for 15-30 mins changing the solution when it starts to go manky, repeat until the acetone remains clear. The main carb body i sonicated in water as i wasnt sure what acetone would do to some of the plastic parts...it tends to dissolve things fairly well. Then i washed the main body in 100% ethanol, making sure that i got it into all the brass bits to clean out any remaining traces of crud. I then used dry 100% nitrogen to remove all traces of the ethanol.
Last edited by banner001 on Fri Apr 28, 2017 3:41 pm, edited 3 times in total.
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Re: How to strip and clean your carbs

Post by BigB » Thu Aug 09, 2012 7:42 pm

quality mate, nice little walk through that!

think maybe some settings need to be added - pilot jet turns etc...

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Re: How to strip and clean your carbs

Post by banner001 » Thu Aug 09, 2012 8:01 pm

i think that all the zxr 400 carbs are the same, manual lists all as CVK-D32...but they all have slightly different settings for things like pilot air jets...im only interested in cleaning, your best bet is to record what the base settings were for your carbs, then re-do these settings after cleaning :D
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Re: How to strip and clean your carbs

Post by BigB » Thu Aug 09, 2012 8:16 pm

may have to add to this then if you dont mind?

where did you take your carbs to clean them mate?

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Re: How to strip and clean your carbs

Post by banner001 » Thu Aug 09, 2012 9:32 pm

will do, and i work as a doctor in a research institute so i have access to every chemical/solvent known in the western world and loads of equipment, plus we have a onsite workshop with 3 excellent guys in there, so i can even get stuff fabricated for a price :D

if you can get hold of a sonicator, you can probably buy acetone online, if not even something like meths/turps will be fine for brass parts, which all the jets are made of, you can also put a bit into the recesses that the jets screw into to, you have just gotta be careful with solvents and plastic/rubber.
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Re: How to strip and clean your carbs

Post by banner001 » Thu Aug 09, 2012 9:45 pm

one other note, always use distilled water, this you can definitely buy, halfords etc will sell it for use in radiators.

you can use this instead of acetone (but it wont be as good), just give everything a good blast of carb cleaner before hand and afterwards.

EDIT, failing that i might setup a sideline business, £20 for carb cleaning -p&p :D
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Re: How to strip and clean your carbs

Post by BigB » Fri Aug 10, 2012 9:28 am

banner001 wrote:one other note, always use distilled water, this you can definitely buy, halfords etc will sell it for use in radiators.

you can use this instead of acetone (but it wont be as good), just give everything a good blast of carb cleaner before hand and afterwards.

EDIT, failing that i might setup a sideline business, £20 for carb cleaning -p&p :D
do it ;) was gona ask if i could send them to you ;) lol

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Re: How to strip and clean your carbs

Post by masterofinsanity » Fri Aug 10, 2012 12:04 pm

cool writeup, cheers!!!
Don't forget people there is more to the zxr400 than this forum... check out www.zxrworld.co.uk also.

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Re: How to strip and clean your carbs

Post by banner001 » Fri Aug 10, 2012 1:18 pm

no probs baz, ill finish the others at some point...

its definitely summat that the site needs, a proper detailed (with pictures) step-by-step guide to doing most/everything on the bike :D
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Re: How to strip and clean your carbs

Post by BigB » Fri Aug 10, 2012 1:30 pm

Baz, is it worth sticking this at all??

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Re: How to strip and clean your carbs

Post by Tirpitz » Fri Aug 10, 2012 3:13 pm

Excellent :smt023 These walk-through write-ups with pictures are enormously helpful when you come to tackle a job for the first time. Definitely what an owners' website should be all about.

It might be worth mentioning that there is a difference between a Phillips head and what the Japs use, although in most cases you can get away fine with using a Phillips screwdriver on Jap fasteners. The Japs actually use JIS headed fasteners. JIS= Japanese Industry Standard. They are not the same. Where you most frequently encounter problems in using a Phillips screwdriver on JIS fasteners is where the fastener is tight, the head is small and made of soft metal. This is often the case with carbs and electrical components. You can very easily chew up a JIS head this way.

JIS screwdrivers are not easily available but you can get them through a few places mail order. They are particularly popular with the model aircraft crowd as the small size of these things, and the fact they are covered in small, soft JIS fasteners means that a set of JIS screwdrivers is a must.
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Re: How to strip and clean your carbs

Post by banner001 » Fri Aug 10, 2012 8:48 pm

Tirpitz wrote:Excellent :smt023 These walk-through write-ups with pictures are enormously helpful when you come to tackle a job for the first time. Definitely what an owners' website should be all about.

It might be worth mentioning that there is a difference between a Phillips head and what the Japs use, although in most cases you can get away fine with using a Phillips screwdriver on Jap fasteners. The Japs actually use JIS headed fasteners. JIS= Japanese Industry Standard. They are not the same. Where you most frequently encounter problems in using a Phillips screwdriver on JIS fasteners is where the fastener is tight, the head is small and made of soft metal. This is often the case with carbs and electrical components. You can very easily chew up a JIS head this way.

JIS screwdrivers are not easily available but you can get them through a few places mail order. They are particularly popular with the model aircraft crowd as the small size of these things, and the fact they are covered in small, soft JIS fasteners means that a set of JIS screwdrivers is a must.
...is something that looks to have happened a few times to both sets of carbs i have. might have to look for a JIS screwdriver then :D

and thanks :D
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JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

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Re: How to strip and clean your carbs

Post by cookiesol » Tue Aug 21, 2012 2:19 pm

doc banner u ought to stop biting your nails mate biggrin

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Re: How to strip and clean your carbs

Post by banner001 » Tue Aug 21, 2012 8:06 pm

cookiesol wrote:doc banner u ought to stop biting your nails mate biggrin
yeah and the side of my fingers as well...get bored/stressed at work easy especially with long hours etc... still, not a bad writeup :D

brake rebuild will be up soon...kinda got a bit waylaid with work.
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Re: How to strip and clean your carbs

Post by adamhearn » Tue Sep 04, 2012 10:12 pm

Good write up.

I've stripped my carbs 3-4 times and my bike is still running badly :(

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