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How to clean a carb

126K views 100 replies 39 participants last post by  Laceycamille212 
#1 · (Edited)
Ok, i've seen this problem come up alot lately....sooo..i thought i'd post a thread on how to clean a carb. now..first off..let me say..not everyone will have the same carb !..sooo..with that being said..let's move on. first..turn your gas off on your tank, next..loosen the intake boot screw to the cylinder, and also the intake boot from the air box to the carb, now..if you own a trx300 ?..( makes no difference what year )..on the right hand side of the carb..you will see a tiny screw holding the side cover on the carb, remove it..next..on top of that same side of the carb..you will see a 10mm nut..this is your throttle cable tie down nut...loosen it...now remove the side cover...reach in..and lift the throttle cam up..as your doing this..lift the throttle cable's end out of the cam...now on the left top side of the carb..is your choke knob..it's a 14mm..loosen it..remove it..becareful not to strip the threads..it's plastic !!..pull the choke out of the carb..you should now be able to remove the carb from the bike ..now..take it over to a good clean..wel lighted area...a nice work bench does wonders !..if you happen to have a bench vise ? ( these come in very handy at times ! )..put the carb in the jaws of the vise upside down..you should now be looking at 4 screws holding the float bowl on ?..if your not..you have your carb right side up..lol. now..remove those 4 screws..lift the bowl off the carb..your now looking at the guts of your carb..there is roughly 3 jets your looking to find ?..your main jet is the tall brass one..your idle jet is the small jet down inside a holder right next to it..there is a starter jet..( on some models..they are on the side of where the rubber plug is )..on some models..they are sitting right where that rubber plug is. now..with a flat head screw driver..remove the main jet from the carb..you can also use a 7mm socket to remove the whole assmebly..this is how i do it...as you will need to clean the whole thing..lay it on the bench..now..with a narrower flat head screw driver..remove the idle jet from the carb..lay it on the bench. now..with a very small screw driver ... a jewlers screw driver works great..or you can even use a small spoke from an old motor cycle wheel..anything that you can use as a punch..thats small enough to tap the float's holding pin out. after you get the float's holder pin out..pull the float and float needle out..becareful not to loose or drop the float needle !..lay it on the bench. now..on one side ( depends on which way you got your carb in the vise ? ) there is your pilot/fuel mixture screw sitting on the outside of your carbs float bowl....as we have mentioned..count the amount of turns you go inwards lightly !.but..in this case..were not gonna cover that..( that part is covered later )..remove the pilot needle..be very careful when you remove it !!..there is a tiny washer that some ppl drop..and the cats drag off..and never see them again !..lol. now..if your lucky ?..when you remove this needle..you will get all the parts out at once !..if your luck is like mine..you always get the tiny o-ring staying in the bottom of that hole !..lmao....if it stays in there..try to dig it out with some kind of pick..a mechanics pick works great !..after you get that out..look to see if you missed any jets still in the carb ?..most times..i leave the starter jet ( the tiny jet that's either where the rubber plug is ?..or on the side where the rubber plug is ?..i hardley ever take this out..as most try to strip out when removing them !..but if you can get it out..all the better !..now..if your carb has that rubber plug..remove it. ..take the carb out of the vise..flip it right side up..remove the 4 screws from the top cover..as you get down to getting that last screw out..the top will want to spring off..this is because it's got a large spring under it..hold the top down..as your removing that last screw..now lift the cover off..remove the spring..lift the main jet's plunger out of the carb..it's round..and has a rubber diaphram around it, now..with your carb spray cleaner..spray down inside the top..all the holes..everything..BE VERY CAREFUL NOT TO GET THIS IN YOUR EYES !!..IT BURNS !..LOL..sooo..please wear safety glasses !!..with your air compresser..blow the carb out really good..every nook and cranny you can stick that air too. ok..now comes the hard part..as this will make or break your carb cleaning..lol. grab your main jet..with some wd-40..and one wire from a wire brush..spray the main jet down..work that wire through the middle of that jet...then with some air..blow it out..if you got a bench grinder...and has a wire wheel on it..this next part is a breeze..if not..your gonna have to do it old school..depending on which way you go..i use my bench grinder with a wire wheel..( faster !..lol ) i clean the outside of the main jet holder..as you can tell..this has a few small holes on the outside of it ??..these have to be cleaned..carb cleaner ( gum out )..and that wire..poke it through the holes..then blow it out with air. now..grab the idle jet..and do the same thing to it. inspect your float needle..is it dirty ?..gummed up ?..if not..leave it alone. if it is..try taking some very fine steel wool..and lighty.. AND I MEAN LIGHTLY..scuff the outside of the needle..do not rub the tip !!!..now comes the easy part..putting it all back together..and i'm sure you know where everything goes ??..if not..main jet goes in tall holder..idle jet goes in right next to that..and if you removed the starter jet..that's easy to see where it goes..now..lay the float assembly back in the holder..slide the float's holder through the tabs..put the bowl back on..flip the carb right side up..slide your main jet plunger back down in the carb..make sure you put the rubber part back in the right way..there is a round outter part..with a tiny hole in the middle of it..slide the big spring down in the top..place the top on..while holding the top down..get a screw started..then put the other 3 in. now..turn the carb back over upside down..remember that jet needle that had the tiny washer that the cat draged off ?..slide the spring on..then the washer that you had to fight the cat to get back..then the tiny o-ring..put the needle down in the carb..turn the needle down all the way..go very easy..do not over tighten it !..if you break the tip off in the carb..your screwed !..lightly seat the needle down in the carb..now back the needle out 2 1/2 turns..count the turns as your watching the very end of the slot in the screw..so you will know when your turns are 2 1/2 turns out. now put the carb back in the bike. i hope this helps everyone out. if you own a trx250..the top of the carb is flat..3 screws hold it on..this is a little different set up. id get into that..but thats another chapter..lol. added : don't forget to clean the float needle seat with some carb cleaner spray and a Q-tip !..very important.
 
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#84 ·
float needle leak is fixed. either the speck of dirt that was missed where it seats, or using the other needle from the shop attempt at carb rebuilding, took care of that. the o-ring/brass screw thing to replace rubber plug? the carb is not leaking. the o-ring i used for the plunger cover does not leak. hope all this holds out. the strange thing is that the atv seems quieter when it runs. it also no longer has that big, KER-BLAM back fire when you decelerate either. its a different atv. i thought that big backfire was pretty much normal for this year, from what i have read here, maybe at a couple of other sites also.[this is the place to go for the best info though]. hiccup is all but gone, though faintly lingers on. a ghost in the machine. hope all this rambling helps someone else //Ed
 
#85 ·
2001 rancher 250 OEM carb issue.

after sitting for about 18months , I decided to pull this atv out and get it running again.
I pulled the carb out and cleaned it out and replaced the jets and pilot screw and o rings and spark plug.

it fired up almost right away and idles like a champ. after idling for a few minutes, I rev it up and right up to the few 1000 rpm it runs great, but then starts sputtering and gasping for fuel. I can put 2-3 finger over the air intake and it starts to run great. I've backed the pilot screw out 4-5 turns and still not running right.

I pulled the carb out and cleaned it out all over again and checked all the settings. fired up and same issue.
I suspect that the vacuum piston is not fully retreating up out of the opening and thus not pulling the needle up out of the needle jet.
that piston and diaphragm look in good shape and no pin holes or tears in the rubber. it appears to seat in the body well.
I'm going to reinstall the carb and see if I can get a few of that piston position at full throttle when it should be all the way up to let max fuel and air into the throat.

the spark plug shows it running lean with no black anywhere.

gary
 
#86 ·
I realise that this is an old sticky that has already helped countless folk but I edited the formatting of the shadtree's original instructions so my small brain can follow it easier. Thought others may find that useful too:

"Ok, i've seen this problem come up a lot lately....sooo..i thought i'd post a thread on how to clean a carb. now..first off..let me say..not everyone will have the same carb !..sooo..with that being said..let's move on.

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DISASSEMBLY
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1. Turn your gas off on your tank.

2. Loosen the intake boot screw to the cylinder, and also the intake boot from the air box to the carb.

3. If you own a TRX300 (makes no difference what year) on the right hand side of the carb you will see a tiny screw holding the side cover on the carb. Remove it.

4. On top of that same side of the carb you will see a 10mm nut. This is your throttle cable tie down nut. Loosen it.

5. Now remove the side cover. Reach in and lift the throttle cam up. As you're doing this, lift the throttle cable's end out of the cam.

6. On the left top side of the carb is your choke knob. It's a 14mm. Loosen it and remove it. Be careful not to strip the threads (it's plastic!!). Pull the choke out of the carb.

7. You should now be able to remove the carb from the bike.

8. Take it over to a good clean well-lighted area. A nice work bench does wonders! If you happen to have a bench vise (these come in very handy at times!), put the carb in the jaws of the vise upside down. You should now be looking at four screws holding the float bowl on. If you're not then you have your carb right side up (lol).

9. Remove those four screws. Lift the bowl off the carb. You're now looking at the guts of your carb. There are roughly three jets you're looking to find:
i) Your main jet is the tall brass one.
ii) Your idle jet is the small jet down inside a holder right next to it
iii) There is a starter jet. On some models they are on the side of where the rubber plug is. On some models they are sitting right where that rubber plug is.

10. With a flat head screw driver remove the main jet from the carb. You can also use a 7mm socket to remove the whole assembly. This is how i do it as you will need to clean the whole thing. Lay it on the bench.

11. With a narrower flat head screw driver remove the idle jet from the carb. Lay it on the bench.

12. With a very small screw driver or anything that you can use as a punch that's small enough, tap the float's holding pin out. A jewellers screw driver works great; or you can even use a small spoke from an old motor cycle wheel. After you get the float's holder pin out, pull the float and float needle out. Be careful not to lose or drop the float needle! Lay it on the bench.

13. On one side (depends on which way you have your carb in the vise) there is your pilot/fuel mixture screw sitting on the outside of your carbs float bowl. As we have mentioned, count the amount of turns you go inwards lightly! In this case we're not gonna cover that (that part is covered later). Remove the pilot needle. Be very careful when you remove it!! There is a tiny washer that some ppl drop, and the cats drag off, and you never see them again! lol.

14. If you're lucky when you remove this needle you will get all the parts out at once! If your luck is like mine you always get the tiny o-ring staying in the bottom of that hole! lmao. If it stays in there, try to dig it out with some kind of pick. A mechanics pick works great! After you get that out, look to see if you missed any jets still in the carb? Most times I leave the starter jet (the tiny jet that's either where the rubber plug is or on the side where the rubber plug is). I hardly ever take this out as most try to strip out when removing them! But if you can get it out all the better!

15. If your carb has that rubber plug, remove it. Take the carb out of the vise. Flip it right side up. Remove the 4 screws from the top cover. As you get down to getting that last screw out the top will want to spring off. This is because it's got a large spring under it. Hold the top down as your removing that last screw.

16. Lift the cover off. Remove the spring. Lift the main jet's plunger out of the carb (it's round and has a rubber diaphragm around it).

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CLEANING
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1. With your carb spray cleaner, spray down inside the top. Spray all the holes, everything. BE VERY CAREFUL NOT TO GET THIS IN YOUR EYES!! .IT BURNS! (LOL) sooo please wear safety glasses!! With your air compressor, blow the carb out really good. Hit every nook and cranny you can stick that air into.

2. OK, now comes the hard part as this will make or break your carb cleaning (lol). Grab your main jet. With some WD-40 and one wire from a wire brush, spray the main jet down. Work that wire through the middle of that jet then with some air, blow it out.

3. If you have a bench grinder, and it has a wire wheel on it, this next part is a breeze. If not, your gonna have to do it old school. Depending on which way you go (I use my bench grinder with a wire wheel as it's faster! lol); clean the outside of the main jet holder. As you can tell this has a few small holes on the outside of it. These have to be cleaned with carb cleaner (gum out) and that wire. Poke it through the holes then blow it out with air.

4. Grab the idle jet and do the same thing to it. Inspect your float needle. Is it dirty? Gummed up? If not, leave it alone. If it is, try taking some very fine steel wool and lightly (AND I MEAN LIGHTLY) scuff the outside of the needle. Do not rub the tip!!!

5. Don't forget to clean the float needle seat with some carb cleaner spray and a Q-tip! Very important.

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REASSEMBLY
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1. Now comes the easy part; putting it all back together. I'm sure you know where everything goes? If not;
i) main jet goes in tall holder,
ii) idle jet goes in right next to that,
iii) if you removed the starter jet. That's easy to see where it goes.

2. Lay the float assembly back in the holder. Slide the float's holder through the tabs. Put the bowl back on. Flip the carb right side up.

3. Slide your main jet plunger back down in the carb. Make sure you put the rubber part back in the right way. There is a round outer part with a tiny hole in the middle of it. Slide the big spring down in the top. Place the top on while holding the top down. Get a screw started, then put the other three in.

4. Turn the carb back over upside down. Remember that jet needle that had the tiny washer that the cat dragged off? Slide the spring on, then the washer that you had to fight the cat to get back, then the tiny o-ring. Put the needle down in the carb. Turn the needle down all the way. Go very easy. Do not over tighten it! If you break the tip off in the carb you're screwed! Lightly seat the needle down in the carb. Now back the needle out 2 1/2 turns. Count the turns as you're watching the very end of the slot in the screw so you will know when your turns are 2 1/2 turns out.

5. Put the carb back in the bike.

I hope this helps everyone out. If you own a TRX250, the top of the carb is flat. Three screws hold it on. This is a little different set up. I'd get into that, but thats another chapter (lol)."
 
#87 ·
I’m gonna keep it short cuz I’m eating pizza drinking beer and watching the series.

I appreciate your taking the initiative to improve a process but there some things I disagree with:

I like that you mentioned the 7mm socket for pulling the main jet—and the oring hooks.

I don’t like that you recommend the wire wheel—don’t do it—use a copper brush by hand or you’ll ruin the finish. Why are you roughly polishing the outside anyway? Has nothing to do with performance.

I spray down and clean the outside of my carbs before I disassemble them, so I get big particles of before I break it down

I don’t like your use of the vise—not necessary.

Ok the guys are giving me the biz cuz I’m texting—good on ya but there’s some techniques you use that I wouldn’t ?
 
#88 · (Edited)
I’m gonna keep it short cuz I’m eating pizza drinking beer and watching the series.

I appreciate your taking the initiative to improve a process but there some things I disagree with:

I like that you mentioned the 7mm socket for pulling the main jet—and the oring hooks.

I don’t like that you recommend the wire wheel—don’t do it—use a copper brush by hand or you’ll ruin the finish. Why are you roughly polishing the outside anyway? Has nothing to do with performance.

I spray down and clean the outside of my carbs before I disassemble them, so I get big particles of before I break it down

I don’t like your use of the vise—not necessary.

Ok the guys are giving me the biz cuz I’m texting—good on ya but there’s some techniques you use that I wouldn’t ��
I am at a loss here ^^^ ??. I use the wire wheel to LIGHTLY knock off the outside of the main jet tube , its not like I am grinding the heck out of it ?..lol. second : I use my bench vise to hold the carb, as some jets are very tight to remove if they have never been replaced ?, it helps to have TWO hands at times !..lol. last but not least : everyone has their own way to clean a carb ?..me ?..I have been doing it this way for over 25 years..and not once have I cleaned a carb, and it not run ??!!..sooo..to each their own :).
 
#93 ·
most pilot jet needles are turned from lightly seated out, for about 2 1/4 turns. you watch one end of the slot in the top of the jet, go half turns or full turns, makes not difference , once you get a full 2 turns out from lightly seated, turn it another 1/4 of a turn. this is factory settings.
 
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#92 ·
Lol my daughter’s snow machine wouldn’t start; she you-tubed removal and disassembly.

She set it up on my workbench, and used my tools and carb stuff to disassemble and clean it. She Reassembled and installed it says it runs great now.

All i did was coach, remove the main jet and emulsion tube (stuck) and used Hondabond on the brittle bowl gasket.

Told her I would have her rebuild a QA03A next!
 
#97 ·
Are you saying a rebuild carb kit is not necessary? If any pieces or parts are broken or missing, is there a certain rebuild carb brand you recommend? My 2001 Honda Rancher has always been rock solid. Recently I can't even get it to run/idle or have enough power to put into gear and go. I'm going to attemp to clean the carb this weekend. Any help is appreciated!
 
#98 ·
A rebuild kit is not always necessary but a 20 yo carb might need new gaskets. Yes your carb sounds like it needs a cleaning and perhaps a choke (SE) valve.
Service manual and parts links are in my signature block below

you can buy a Honda gasket kit, which has the most common gaskets you’ll need—it also has a passage plug which sometimes requires replacement but it doesn’t have a float valve.

you can also buy a Shindy kit, which has everything you’ll likely need to completely rebuild your carb, but it doesn’t have the passage plug.

the SE valve is sold separately and you cannot just replace the seal.
 
#100 ·
thanks for the comment..as for your pilot jet screw..i hope you made sure you got all the old parts outta that tiny hole ??..sometimes it's a pain to get that tiny o-ring out..if you left it inside the carb..it will throw your settings out of wack..as for the turns out..helmut has you covered.
Shade tree,

Sorry to bother. I have a quick question you maybe able to answer. I just purchased a 2003 Honda Foreman 450 s 4x4. This is my first ATV. The clutch lever on the handlebar only has pressure on it when i push the red button to put it it into reverse. Otherwise, the clutch lever will move back and forth without any pressure. Many years ago when i rode motorcycles you would pull the clutch lever to shift gears. Should the clutch lever activate the clutch when shifting from !st to 2nd and so on?
I’m having to put brakes on it as it doesn’t have any brakes. It has a freshly rebuilt motor. That is why i thought it is worth saving. Thanks! Marshall Taylor
Email address: martainc@bellsouth.net
 
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