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cbr900racer77
May 26th, 2009, 04:22 PM
Okay, this is something this site has needed for a long time. A couple of guys besides me were gonna do it, but I guess they got caught up with life (like me) and never got around to doing it. I'd bet gummed up carbs is by far the most popular problem bikes can have. They sit in the garage with old fuel in them for months and the gas gums them up. Cleaning carbs is super easy. I'm not the best at doing how-to's, so bear with me. When I'm done, feel free to point out something I've missed or something you'd like to add. Okay, here goes...
I'm not mentioning removing the airbox or carbs. My bike is track only and stripped to the bone so pics of mine wouldn't do you any good. Grab a good manual and use it as a guide. First things first...use a quality carb. cleaner. In my opinion, B12 by Chemtool is BY FAR the best cleaner on the planet!! Start with a clean, dry place to work. A clean soft cloth is ideal for a work surface in case something falls (it won't bounce far on the cloth).

cbr900racer77
May 26th, 2009, 04:28 PM
The order I'm doing this is just how I do it. I'm just doing 1 carb here. You can disassemble all 4 carbs at once if you'd like (it's easier and faster). Just be sure and keep 1 carb's parts with that carb. The fuel mixture screws are the only exception, do them ONE AT A TIME! (I'll explain later). Start by removing the 3 screws holding the top cover on. Then remove cover, spring, and slide (be gentle with the slide)

cbr900racer77
May 26th, 2009, 04:31 PM
This next step normally isn't necessary, but I'm including it anyways. If you have OCD or something, you may want to do it. Remove 4 screws that hold stack to back of carb. Remove cover and stack, then remove O-ring type gasket. I'll explain why you may want to do this step in a few minutes.

cbr900racer77
May 26th, 2009, 04:37 PM
To remove fuel screws, you need a special tool. If you don't want to pay a rediculous price for it or can't borrow one...here is how to get around it. Turn carbs over. Take a dremel tool with thin cutoff wheel and lightly cut a small channel across the head of the screw. Cut it just enough to be able to get a small flathead screwdriver in there and get screw out. Screw them in and count the turns and write it down. This way when you are installing them, you can get them back to where they were. After you get screw out, use a small pick with a hook on the end and dig out the spring. After the spring, there is a small metal washer. Then last there is a small rubber washer. Take your time here so you don't drop any of them, it's VERY easy to do. Do each screw one at a time. If you try all four the likelihood of dropping something is multiplied.

cbr900racer77
May 26th, 2009, 04:41 PM
Remove the 3 screws holding the bowl on and remove the bowl. Sometimes they are stuck and you need to lightly tap them with wooden screwdriver handle or something else that is fairly soft.

cbr900racer77
May 26th, 2009, 04:50 PM
Next, remove the pilot jet, main jet, emulsion tube (7mm wrench), and float/needle assembly (careful you don't drop the needle when lifting the float)

cbr900racer77
May 26th, 2009, 04:54 PM
Now it's time to do some cleaning. Cleaner is under alot of pressure and B12 will eat some eyeballs up so be careful using it. It will also get in open sores/cuts and burn like hell! Use an old toothbrush to clean inside bowl and a clean shoprag soaked in B12 to get in the corners. Anything that is a dull orange color needs to be cleaned. Using the red tube that came with cleaner, squirt some down hole in rear of carb. This is the air supply for pilot jet.

cbr900racer77
May 26th, 2009, 04:58 PM
Next squirt generous amounts of cleaner in holes for pilot jets and fuel screws. If you look at front of carb, there is a small port in front of butterflies. Cleaner should come out this port when spraying down pilot jet and fuel screw holes. If it doesn't, keep spraying it (alternating with compressed air) until it does. When a good stream is coming out the port, you know it's clean.

cbr900racer77
May 26th, 2009, 05:04 PM
Using the toothbrush and shoprag, clean rest of carb...throat, bowl, anything that has varnish on it. Clean emulsion tube with rag soaked in cleaner (make sure you can see through all the little holes on the sides) then install it (just snug tight). Next clean main jet and install. Then do pilot jet and install. Using rag, wipe off float (be gentle) and needle. Install needle in float and install. Then install bowl and tighten 3 screws.

cbr900racer77
May 26th, 2009, 05:05 PM
Supper time! will continue in a few....

cbr900racer77
May 26th, 2009, 06:16 PM
Next, install O-ring gasket at rear of carb. With it still in cover, install stack. It has 3 cutouts in it that go into slots in back of carb. While making sure Oring is in it's groove, install cover and tighten 4 screws. Take a rag and wipe off tip of needle.

cbr900racer77
May 26th, 2009, 06:23 PM
I've known several people that have trouble installing slides. Sometimes it's hard to get diaphram to seal, here's a trick. Push diaphram down over slide. Gently lower slide into carb body just enough to guide needle into it's hole. Next install spring into slide. Now lower top cover over the spring. Run your finger around the diaphram to make sure it's in it's groove in carb body. Run your other hand through back side of carb and using index finger, hold slide. Push down on the cover with one hand while slightly pushing up against slide with other finger. What you're trying to do is prevent slide from free-falling into carb. When cover is down on carb, hold it down with thumb of hand holding slide. Install the screws and tighten, then let slide fall. You've got it right if you can lift slide and it immediately free falls back down.

cbr900racer77
May 26th, 2009, 06:26 PM
Wipe tip of fuel screws with rag soaked in cleaner. Install spring onto screw, followed by metal washer, then rubber washer. Install screw into carb. Screw in until it lightly seats then back it off # of turns you wrote down when removing. That's pretty much it. They are ready to install. Make sure carbs are seated in boots and airbox is seated onto carbs. Bike will run like shit if either aren't seated properly. If you have any specific questions or need more pics, pm me on here or email me at hondaracer4u@yahoo.com.

cbr900racer77
May 26th, 2009, 06:29 PM
One thing I forgot...while you have float removed, get a Qtip soaked in cleaner and clean seat for the needle. A few good rotations should do it. Blow through fuel line with compressed air to make sure no cotton fibers are left in seat.

CBRR93
May 26th, 2009, 07:45 PM
thanks CBR900Racer
Very good write up. I think you are right about this being a common problem.
I wish I had this info when I did mine.

cbr900racer77
May 26th, 2009, 07:48 PM
yeah, it's easy to get in a slump and not ride your bike, especially if you've owned it for quite a while. Pilot jets are super tiny and clog easily. Carbs can be intimidating, but are quite easy once you get em tore down and get an understanding of how they work. You can use this for just about any carb, they are pretty much the same.

jawhn
May 26th, 2009, 10:32 PM
Just made this a sticky.

Has anyone told you how awesome you are, yet? Let me be the first! ;) Well done!!!

gothy
May 27th, 2009, 02:47 AM
Good write-up there m8.

Im gonna be cleaning my carbs, when its dry one day this week. bloody uk weather;DOH

a_morti
May 27th, 2009, 04:44 AM
Brilliant writ up. Exactly how I did mine. For the needles, there are so many tiny channels, where my bike had been stood with fuel in it for two years, they were quite bad. I took all the removable needles and screws out, soaked them in a vodka bottle lid (metal, unlike coke bottles) of cleaner, blew them through with a spray duster can, and repeat as needed. Amazing how much green and white crap you can remove from such a small component.

Be VERY careful with removable parts, they are brass and soft. Do not try to remove anything with an ill-fitting screwdriver (ask how I know).

My fuel screws came out easy - are they different in the Dynojet stage 1 kit? As my bike has that fitted.

Worth noting that it's a good idea to think about why your carbs are messy. Maybe it's obviously just time and build-up, or a long lay-up, but maybe your fuel filter gauze is ripped in the tank. I am not so impressed with the design of that. Cleaned the carbs three times before I thought to check it, so I'll mention it and maybe save someone heartache and irritation. You can fit an aux filter in the fuel line (just, it's tight) on later bikes with no pump, no idea on earlier bikes though.

cbr900racer77
May 27th, 2009, 05:57 AM
EXCELLENT point a_morti! Forgot to mention taking it easy on the jets. They are soft and can easily be deformed with wrong size screwdriver. Don't try to clean them with a staple or paper clip, you'll scratch the hell outta them and could possibly change opening size. When you're tightening them, just a snug fit is enough. As for the fuel screws, the ones you get with jet kits already have slots for flathead screwdriver. It's just the stockers that are wierd. Do ya'll call em flathead screwdrivers in the UK? I have no idea what proper name is...slotted tip maybe?:CONF

CBRryda210
May 27th, 2009, 10:08 AM
Great Post!!

900RR Puzzle
May 27th, 2009, 06:53 PM
Awesome job cbr900racer77. :applause:

Makes me want to go buy a set of carbs to tear into...

gothy
May 28th, 2009, 06:18 AM
EXCELLENT point a_morti! Forgot to mention taking it easy on the jets. They are soft and can easily be deformed with wrong size screwdriver. Don't try to clean them with a staple or paper clip, you'll scratch the hell outta them and could possibly change opening size. When you're tightening them, just a snug fit is enough. As for the fuel screws, the ones you get with jet kits already have slots for flathead screwdriver. It's just the stockers that are wierd. Do ya'll call em flathead screwdrivers in the UK? I have no idea what proper name is...slotted tip maybe?:CONF

yeah flat head screw drivers.

On the earlier models, they have an inline filter just before the fuel pump.

If you want to go poking around in a jet to remove dirt, get a bit of thin electrical cable, cut 1 copper strand and use that, as its plyable, small and wont damage the jets. (im talking normal wiring harness thinkness, say indicator wire thickness but 1 strand)

cbr900racer77
May 28th, 2009, 01:30 PM
Here in the south...if someone mentions "flathead", they're either talking screwdrivers or catfish:Laughs

Tulok
May 28th, 2009, 06:35 PM
haha, I'm pretty sure it's "flat head", though i am going to start calling them slotted tips just to annoy my friends now :P

this is a good write up!
I can't stress the importance of smooth, clean slides enough!
be sure to clean them intensely with carb cleaner (do not oil them!) and make sure that the diaphragm has a good seal. The slide lets the fuel into the engine, if it is binding, or not functioning properly you aren't getting any fuel into the combustion chamber!

jawhn
May 28th, 2009, 08:27 PM
haha, I'm pretty sure it's "flat head", though i am going to start calling them slotted tips just to annoy my friends now :P

this is a good write up!
I can't stress the importance of smooth, clean slides enough!
be sure to clean them intensely with carb cleaner (do not oil them!) and make sure that the diaphragm has a good seal. The slide lets the fuel into the engine, if it is binding, or not functioning properly you aren't getting any fuel into the combustion chamber!

HOLY CRAP, he finally made it on!!! :D

Welcome aboard, Tulok!

robertseber
June 23rd, 2009, 09:54 AM
thanks for the write up good job appreciate it much

rrdude
June 23rd, 2009, 10:33 PM
:)Awsome write up! I was gonna take mine somewhere and have em cleaned but now i think i might tackle them.

itzstreetlethal
June 24th, 2009, 11:49 AM
I did this a day or two ago and now bike CBR is sending raw fuel out the right side vent tube as I start... UGH!!! The write up has been a HUGE help though and thanks for taking the time to explain for us newbs.

cbr900racer77
June 24th, 2009, 02:15 PM
I did this a day or two ago and now bike CBR is sending raw fuel out the right side vent tube as I start... UGH!!! The write up has been a HUGE help though and thanks for taking the time to explain for us newbs.

You my friend have a float stuck. Did you clean needle and seat? I can't remember if that was covered, but I clean the seat with a Qtip soaked in B12 cleaner then blow it out to get cotton fibers out of there. If thorough cleaning doesn't help, you may need new needles. Btw...if someone suggests adjusting the float, forget it. They are non-adjustable.

cbr900racer77
June 24th, 2009, 02:17 PM
:)Awsome write up! I was gonna take mine somewhere and have em cleaned but now i think i might tackle them.

If you have any mechanical experience at all, you can do it yourself (and save some dough). It's not hard at all. Worst case scenario, if you get in a jam you can just snap a pic of problem and post it on here. Several people on here with carb experience. Where is Granite Falls? I've lived in Wilmington, NC for a few years. NC is a very cool state!

legal disclaimer...If you get to a point that is outside your "comfort" zone, STOP and put it back together. I can just see someone coming on here and jumping down my throat cause they botched the job.

rrdude
June 24th, 2009, 07:50 PM
Im about 30 mins south of boone off hwy 321. Yeah i lived in wilmington for a little while myself. Too much traffic lol.

n3cr0
August 15th, 2009, 06:59 AM
BTW, you need to be a contortionist octopus to get those long springs back in after cleaning everything :Laughs

A little patience and a lot of logic also helps.

sempul
December 28th, 2009, 12:08 PM
good post! i just wish i had the confidence for this! i think ill just spend the $300 and have a pro do it. if any of you guys live in louisiana i would be willing to let you guys tackle it lol.

cbr900racer77
December 28th, 2009, 12:15 PM
300 bucks!! sheesh. I normally charge 25 a carb. It's not nearly as complicated as you might think. Have you ever worked on any type of carburetor? Hell, ship em to me and I'll clean em for you. 300 is a rip-off. PM me if interested. I can give references (from members on here).

sempul
December 28th, 2009, 03:08 PM
is that to clean and rebuild? i ask because he is supposed to do a rebuild on it. my problem is i have no lowend power and they also need to be resynched.

cbr900racer77
December 28th, 2009, 03:14 PM
no way to sync them off the bike. You might be better off getting that done locally then. Sorry, wish I was closer or I'd hook you up.

sempul
December 28th, 2009, 03:26 PM
i know i wish you were closer also. so does my wallet lol. well thanks for the offer and i will keep you in mind for when i need just a cleaning lol.

asphaltsurfer
December 28th, 2009, 03:32 PM
great post... if i had this when i first started messin w/carbs would have saved myself many re rebuilds and less than perfect days out on the road:V very well done

cbr900racer77
December 28th, 2009, 04:30 PM
Actually, if you were to hurry, I could stick them on mine and sync them. I haven't torn it down yet. No sense in taking them somewhere and getting screwed up the ass when you get the bill. I'll treat you right.

jawhn
December 28th, 2009, 08:14 PM
sempul, cbr900racer77 is seriously good people, if you need a reference. ;)

Hell, someday I might take you up on that carb cleaning deal... :D

cbr900racer77
December 28th, 2009, 08:42 PM
Always wanted to visit AZ. Spring for the airline ticket and we are in business:Laughs

jawhn
December 28th, 2009, 10:52 PM
Always wanted to visit AZ. Spring for the airline ticket and we are in business:Laughs

Holy shit... I will give that some serious consideration! ;) And you're welcome to couch-trip any time.

xiztence
April 14th, 2010, 05:16 PM
Great write up! I have a 98 cbr 900rr and I started a few hours ago... got the gas tank and intake box off.. disconnected the choke and throttle cables.. and sensor... i loosened the clamps holding the carbs to the engine. but for some reason, i cant get them off?? i dont see anything holding them do0wn... and the clamps are sooo lose that i can turn them (so they're actually not holding anything right now)

any ideas? I have a manual and i followed all the steps... i dont want to force them off..

thanks :V:CONF

Tulok
April 14th, 2010, 05:26 PM
get a long extension or pry bar, wedge it in there. And force them off!
Now get of the computer and get your butt back out there and do it!

cbr900racer77
April 14th, 2010, 06:50 PM
yup, do the ole "wiggle and pull"...be easy prying, make sure you aren't against something that is fragile.

66droptop
April 14th, 2010, 07:59 PM
Do ya'll call em flathead screwdrivers in the UK? I have no idea what proper name is...
Like the Brits would know the proper name for it. What with their weird words like dog's bollocks, bodged, knackered, fish & chips, and getting pissed. Just because your country's name is in the title of the language doesn't give you a free pass to start making up words all willy nilly to see if the rest of us can follow along.



Here in the south...if someone mentions "flathead", they're either talking screwdrivers or catfish:Laughs
The engine is the first thing that comes to mind. It must be too long because I didn't even think of the catfish.

cbr900racer77
April 14th, 2010, 08:28 PM
Them flatheads is good eatin:Laughs

bikerdave
April 14th, 2010, 11:50 PM
I too am in the middle of rebuilding a set of '98 900 carbs.

Mine has 20+ k on it and boy are those boots(if you call service honda

they indicate them as insulators WTF) and boy are they expensive.

It took three or four of us wiggling and tugging and just plain pulling

to finally get them off.

The instructor said there ain't no easy way.

Just think of that rubber(not that thought!!!) having been thru how many

gazzilion heat cycles.

Some one mentioned on here for future reference when they go

back on use some Grease(Oil lubricant!!!!) to help for the next time.

bad dog
April 15th, 2010, 10:11 AM
Some one mentioned on here for future reference when they go

back on use some Grease(Oil lubricant!!!!) to help for the next time.

I use silicone spray, that way it won't damage the rubber or cause them to get damaged. Some lubes will either cause the boots to deterioate or swell, :(

jawhn
April 15th, 2010, 11:54 AM
I remember it was a nightmare getting them off of my CBR600F2... What I ended up doing is taking a longish 2x4 and drilling holes into it that lined up with the holes on the top of the carbs, buying longer screws that threaded into the top of the carbs, then basically mounting the 2x4 to the carbs, then a 3-person deal: Me and Suzanne laying on our backs on the floor, timing our kicks upward, and Jaime holding the bike upright. Came off after a few kicks, but damn if we didn't curse a blue flame trying to get those damn things off first.

bad dog
April 15th, 2010, 12:14 PM
Another option is to get the bike warm first, or use a heat gun/hair dryer to soften up the rubber, helps tons.

xiztence
April 24th, 2010, 12:18 PM
thanks for the advice! i got the carbs off.. i used a hair dryer and warmed the rubber.. then sat on the bike (like I was going to ride) and pulled them off that way.. it helped me get a better grip on them and hold the bike down at the same time.. i cleaned out everything as this how-to specified.. i didn't use a dremel for the fuel screws.. i didn't have a dremel head that small.. so i took the back end of an electrical connector (the plastic ones) and used that to turn the fuel screws... only problem is im not sure if i put them back exactly how they were.. what will happen??

970rr
April 24th, 2010, 08:04 PM
.. i didn't have a dremel head that small.. so i took the back end of an electrical connector (the plastic ones) and used that to turn the fuel screws... only problem is im not sure if i put them back exactly how they were.. what will happen??

grave danger of explosion! don't screw those too tight!!

bad dog
April 25th, 2010, 12:41 AM
thanks for the advice! i got the carbs off.. i used a hair dryer and warmed the rubber.. then sat on the bike (like I was going to ride) and pulled them off that way.. it helped me get a better grip on them and hold the bike down at the same time.. i cleaned out everything as this how-to specified.. i didn't use a dremel for the fuel screws.. i didn't have a dremel head that small.. so i took the back end of an electrical connector (the plastic ones) and used that to turn the fuel screws... only problem is im not sure if i put them back exactly how they were.. what will happen??

If your talking about the mixture screws, then you'll have a crappy idle.

cbr900racer77
April 25th, 2010, 08:21 AM
yup, those need to be right. You need to have a good grip on them so you know you don't seat them too tight and get them turned out right amount. The cutting wheel I use is normal size so it does cut into carb body slightly, but has no ill effects. I need to break down and buy that tool one of these days:rolleyes:

xiztence
April 25th, 2010, 11:29 AM
thanks.. i got everthing back together and my bike still won't start.. i will create a new post in the 900rr section.. :CONF

Mobley
April 26th, 2010, 07:44 PM
Thanks for the write up. I was confident i could figure it out but it was nice to have a guide if I screwed up. Got them cleaned but didn't find much crud so I am thinking that wasn't my problem. Oh well it still needed to be done I will know for sure tomorrow. Oh yeah and no joke about B-12 eating eyeballs.

cbr900racer77
April 26th, 2010, 08:20 PM
I've tried them all and B-12 kicked everybody's ass in cleaning dept. That shit is wicked. Other day my next door neighbor was over while I was working on his 3wheeler. Noticed he was spraying something trying to kill bumble bees flying around. Looked and seen it was a can of my beloved B-12. Had to jump all over his shit, that stuff ain't cheap:Laughs Btw, killed the bees on contact.

novadose427
May 18th, 2010, 08:13 PM
Now it's time to do some cleaning. Cleaner is under alot of pressure and B12 will eat some eyeballs up so be careful using it. It will also get in open sores/cuts and burn like hell! Use an old toothbrush to clean inside bowl and a clean shoprag soaked in B12 to get in the corners. Anything that is a dull orange color needs to be cleaned. Using the red tube that came with cleaner, squirt some down hole in rear of carb. This is the air supply for pilot jet.

Hi i am new to the forum. My name is Brian. In process of cleaning my carbs now..the one you have the red tube pointed at, air goes thru all of mine.
The one to the left and 2 up, doesnt seem like any air is getting thru on all four carbs. Do you know where it should be coming out from? Thanks for your time.

cbr900racer77
May 18th, 2010, 08:46 PM
cleaner will come out hole where pilot jet goes, hole where fuel screw goes and out tiny hole in front of the butterflies.

Elbee
July 24th, 2010, 12:12 PM
Fantastic. Thank you for all the work in putting the pictures together with the right words! :V

salty311
July 25th, 2010, 04:21 PM
A bit off subject dude, but I have a 98 rrw blade, I was wondering (although mine has not) if they ever had and in line fuel filter or fuel pump?

Nath.

cbr900racer77
July 25th, 2010, 04:28 PM
Yes, early (893) models had fuel pumps. Don't think they have ever had inline filters.

salty311
July 25th, 2010, 04:49 PM
Have you got any pictures to show me please? Believe it or not, my bike has only a single tube from the tank strait into the back of the carbs.

cbr900racer77
July 25th, 2010, 07:46 PM
Pictures of what? You should only have one 3/8" feed line from tank to carbs and one small tube for vacuum petcock.

salty311
July 25th, 2010, 11:23 PM
Cheers, I was after a fuel pump pic but if thats all Im ment to have then no worries.

jawhn
July 28th, 2010, 03:34 PM
And fyi, all our 900s have 'inline' filters... They're just inside the tube to the tank that the petcock screws onto. It's that orangey mesh inside there... :z