Honda CRF230F - Carburetor Notes

March 14, 2018 version

Tools you'll need

1/4" drive ratchet, short extension, 6mm and maybe 7mm sockets
17mm open/box wrench
Medium blade screwdriver

Drain the carb

Use the screwdriver to loosen the drain screw near the bottom of the carb float bowl. When fuel comes out of the drain hose, catch it in a small container. Retighten the screw.

Use the open/box wrench to loosen the cap on the bottom of the carb float bowl. Use a rag to sop up any fuel as it dribbles out. Don't let any fuel reach the engine or pipe if they are hot from recent running.

Unscrew the cap with your hands, being careful not to spill the fuel in the cap.
 
 

Inspect the fuel to see if there is any water or debris. Dump the fuel into a small container and dispose of properly.
 

Connect the 6mm socket to the 1/4" ratchet. Use the ratchet to loosen the main jet. You may have to push the bottom of the carb body around a bit to get the socket to seat on the main jet. You don't want the ratchet or socket hitting or dragging against anything. You also may have to loosen the carb band screws to wiggle the carb body around or tilt the carb slightly until you get a clean connection.

After the main jet is loose, remove it completely using your fingers.
 
 
 
 

Try not to drop it in the dirt. Look through the hole in the main jet to see if it is clean. If the hole is obscured, wait a few minutes for the fuel to evaporate, then check again. It's always a good idea to check the condition of jets as you remove them to see if any irregularities could have been contributing to a problem.

If the main jet comes out attached to a long brass part, don't panic. The long brass part is the needle jet holder. Disconnect the main jet from the needle jet holder using a small crescent wrench and a 6mm socket connected to the 1/4" ratchet.

Connect a 7mm socket to the short extension. Using your fingers, use the socket/extension to screw the needle jet holder back into the bottom of the carb until it's snug. Then connect the short extension to the 1/4" ratchet. Use the ratchet to tighten the needle jet holder. Do not over tighten; snug and a bit more is good.

Verify that you have the correct main jet by checking the number embossed on the new main jet. Look through the hole in the new main jet to make sure there is no debris blocking it. Make sure the main jet is clean, and the threads are in good shape.
 
 
 
 

Connect the 6mm socket to the short extension. Using your fingers, use the socket/extension to screw the main jet until it's snug.
 
 
 
 
 

Connect the 6mm socket to the 1/4" ratchet. Use the ratchet to tighten the main jet. Do not over tighten; snug is good. You may have to push the bottom of the carb body around a bit to get the socket to seat on the main jet. You don't want the ratchet or socket hitting or dragging against anything so that you can judge the tightness of the fit and not over tighten. You also may have to loosen the carb band screws to wiggle the carb body around or tilt the carb slightly until you get a clean connection. Be patient; this is the most important part.

Screw the bottom cap in by hand.
 
 
 

Tighten the bottom cap using the 17mm open/box wrench. Don't over-tighten.

Turn the fuel petcock on and check for leaks. Ride.

You can change the needle and/or adjust the needle clip without removing the carburetor from the motorcycle. You may have to remove the seat and gas tank. You must be able to get to the top of the carb and remove parts through it. If you can tilt the carb body out from below the gas tank enough to see the entire top of the carb, then you're set. If you are using the stock throttle cable setup with both a pull and push cable, then tilting the carb becomes very difficult because the cables are in the way. If this is the case, remove the seat and tank and begin work. If you are using a non-stock throttle cable setup, such as only one pull cable, then you can remove the single cable and tilt the carb.

In 2008, Honda changed the orientation of the link and link arm, so my procedure will not work on 2008 and newer carbs.
The more difficult procedure is described in Red Mesa's CRF230F Shop Notebook:  Changing the carburetor needle on a 2008 and later model

Tools you'll need

Medium blade screwdriver
Phillips #2 screwdriver
Phillips #1 screwdriver
10mm open/box wrench - two
Special tool or wire hook or small needle nose pliers

Note about the special tool:

The special tool used for this work is an SW-10 Swinger Hook made by Ullman Devices Corp, Ridgefield, Conn. You may be able to find the tool at your local hardware store. If not, try the web. I ordered several of these tools in 2001 from Kipper Tool for about $5 each (shipping extra). If you can't locate the tool, make a wire hook from number 14 or 16 bare copper wire or similar. A small pair of needle nose pliers will also work.

2013 update - Amazon sells the SW-10 Swinger Hook for about $7.

View of the single-pull throttle cable

Use the two 10mm box/open wrenches to loosen the lower nut. Hold the cable housing with one wrench, while you turn the lower nut with the other wrench. Slip the cable out of guide and move it behind the guide, out of the way.

Loosen the rear band screw using the Phillips #2 screwdriver.
 
 
 
 

Loosen the front band screw using the Phillips #2 screwdriver. Tilt the carb out so you can see the entire top.
 
 
 
 

Remove the screws from the top of the carb using the Phillips #2 screwdriver.

Peek inside.

Remove the link arm locking screw using either Phillips screwdriver. I like to use the #1.

Raise the slide using the Swinger or wire hook.

Grasp the link and use the Swinger, wire hook, or small needle nose pliers to remove the retaining spring.

Slide the link sideways off of the link arm and the slide arm. Rotate the link arm up and out of the way.

Raise the slide using the Swinger or wire hook.

Removed parts:
Slide, link, spring, screws, top

Unscrew the small screws inside the slide using the Phillips #1 screwdriver. Be careful when removing the screws because the needle retainer has a spring under it, and it will rise up as you unscrew the screws. Remove the retainer, then tip the slide over to remove the needle.

The needle retainer with screws and spring.

NOTE -- I read about an alternate method of removing the needle that reduces the possibility of bending the needle. Using my method described above requires that you hold the slide in one hand while you loosen and unscrew the small screws in the bottom. The screws are often seated very tightly and require significant force while rotating the screwdriver and solid seating of the tip into the screw head. During this process, the cheek of your hand could roll over the edge of the slide and push against the needle, bending it. You may not even notice it, especially if you have large hands as I do.

The alternate method is to loosen the screws while the slide is still inside the carb body. There is no possibility of bending the needle with this method. The only problem is, it's difficult to do this with the carb still in the carb boots and rotated. You must steady the carb while you break the screws loose and that's easiest with the carb removed from the boots and in your hand. At least for me. If you can do it with the carb in place, go for it. Otherwise, pop the carb out of the boots.

After you change the clip position (described below), install the slide into the carb body before re-installing the screws. Don't over-tighten the screws - you may have to adjust the clip position again. I tighten to snug and a bit more. The lock washers should be an insurance against under-tightening.

Remove the clip from the needle. I use my fingers instead of tools. Hold the clip/needle against a hard surface with the open end of the clip pointing down. Cover the clip with a finger from one hand and press the needle down with a finger from the other hand. Press firmly, and the clip will slide off the top of the needle. Be careful the clip doesn't go flying off. Maybe you should do this in a place where you could spot the clip if it pops out of your hands ;-)

Place the clip in its new location and press it back onto the needle. Again, I use fingers from both hands and work against a hard surface. Face the open end of the clip pointing up with the needle on top. Press down on the needle, and the clip will pop into place. Rotate the clip on the needle to make sure it's in the groove properly.

Caution: if you use pliers to remove and replace the clip, you may crimp the clip enough so that it doesn't fit properly on the needle or completely into the needle groove.

Drop the needle back into the slide and put the retainer, with the spring, over it, aligning the holes in the retainer with the holes in the slide. Make sure the spring is on the needle, pressing down on the clip. The retainer arm must be aligned to point to the right of the slide (the top slide cutout is to the rear).

Screw in the small screws using the Phillips #1 screwdriver. Don't over tighten because you may have to remove them some time in the future; snug and a bit more is good.

Put the slide back into the carb, aligning the top cutout to the rear. Don't drop it in; slide it in slowly until it bottoms.

Place the link onto the slide arm and the link arm.

Install the spring within the link. Check that the slide goes up and down by raising and lowering the link arm.

Make sure that the link is pushed all the way to the left on the slide arm. The spring must seat in a groove on the slide arm. This picture shows an INCORRECT position of the link.

Screw in the link arm locking screw; don't forget the lock washer. Don't over tighten; the lock washer works. I use the Phillips #1 screwdriver, but either will work.

To help line up the holes for the screw, do two things:

1. Push the throttle drum to the right, towards the carb body. This gets the inner shaft into the correct position. (The throttle drum is the round metal plate on the left that the throttle cables are connected to.)

2. Raise the link arm just a bit. This rotates the outer shaft so the holes in both shafts line up.

Look into the screw hole as you do this to see which action aligns the holes best. You can even do both actions at once and when the holes line up, slip the screw into place.

After the screw is tightened, rotate the throttle drum to check that the link arm and slide operate correctly.

Replace the carb top and screw in the two screws using the Phillips #2 screwdriver.

Rotate the carb to vertical and make sure that the tab on the front of the carb is aligned with the rubber alignment slot on the intake boot. Tighten the front and rear band screws.

If the throttle cable was removed, use the two 10mm box/open wrenches to reinstall it.
 
 
 
 
 
 
 
 
 
 

Operate the throttle to make sure that everything works. You should hear a small clunk when the slide hits the bottom of the carb as you roll-off the throttle. Reinstall the tank and seat if they were removed and go riding.
 
 
 
 
 
 

To install an extended fuel screw, you must remove the carburetor from the intake boot and airbox boot, so you can get to the lower front of the carb. You may be able to remove the carb without removing the seat and gas tank, but it's very difficult. I recommend that you remove the seat and tank first.

Note: Although I, and many others, call this part a fuel screw, Honda calls it a pilot screw. We use the term fuel screw to distinguish between this part for four strokes and the 2-stroke version, called an air screw. This is done so we can be ever mindful that screwing the "fuel" screw in and out adjusts the amount of "fuel" we are adding to the mix; 'in' is leaner (less fuel), and 'out' is richer (more fuel).

There are three fuel screws that this section is concerned with:

the stock Honda '03-'05 fuel screw (left),
the stock Honda '06 and up fuel screw (center),
and the Kouba extended fuel screw (right).

The head of the shorter '06-and-up fuel screw is recessed in the carb body and is difficult to get to when you want to adjust the fuel screw. Honda has put these shorter D-bit-head fuel screws on many CRF models to comply with CARB, the CA agency that sets emission standards for CA motor vehicles.

On newer carbs, the fuel screw chamber has a metal cap that is pressed in to cover the fuel screw and prevent adjustment. On the newest CRF250X carbs, there is a locking pin installed also.

By installing an extended fuel screw, you make it easy to adjust the fuel screw by hand. Small tweaks to compensate for temperature swings are easily done using your finger on the T.

You can buy the Kouba extended fuel screw from:
KoubaLink PN FS-3: $20 (min. order of $25 - domestic shipping included);
CRFsOnly about $20, shipping extra.

If you have an '03, '04, or '05 230F, use a small screwdriver to unscrew the stock fuel screw.

If you have an '06 or newer 230F, the head of the fuel screw is D shaped, and a regular screwdriver will not work. You can use a D bit (sold by Motion Pro for about $2.90 plus shipping).

You'll also need a driver for the bit: it's a 1/4" hex drive. I used a short 1/4" hex socket and a manual drive handle.
 
 
 

If you don't want to buy the D bit, you can try using a small jeweler's screw driver to fit in along the flat edge of the D and try to rotate the stock fuel screw out. A dental pick may also be used. DO NOT drill out the stock fuel screw; you may ruin the carb.

The 2013 and 2014 model carbs have a brass cover over the fuel screw. You can try to remove it with a pair of needle-nose vise-grips or other tool. Another choice is to drill a small hole in it, then thread a screw in, then pull on the screw to remove the cover. You could also put a very small hook in the hole and pull; use the Swinger hook if you have it. If you have an after-market extended fuel screw that you will be installing, you don't have to worry too much about damaging the stock fuel screw hiding under the cap.

Caution - don't put any pressure on the fuel screw chamber itself; the cast material is not strong and the chamber can be broken off. Honda does not sell individual carb body parts - if you break the chamber off, you have to buy a whole new carb!

I have not seen but have read that 2015 and newer carb models have a pin installed further blocking removal of the fuel screw.

See Changing the needle and/or adjusting the needle clip for a description of the Swinger hook.

Tools you'll need

Medium blade screwdriver
Small blade screwdriver
Phillips #2 screwdriver
D bit, hex socket, driver
 
 
 
 
 

Drain the carb

Use the screwdriver to loosen the drain screw near the bottom of the carb float bowl. When fuel comes out of the drain hose, catch it in a small container. Retighten the screw.

Remove the end of the upper rubber vent hose from the retaining tab on the upper frame backbone tube.
 
 
 
 

Remove the end of the lower rubber drain hose from the retaining tab on the frame under the swingarm and behind the rear brake pedal.

Loosen the rear band screw using the Phillips screwdriver.

Loosen the front band screw using the Phillips screwdriver.

Pull the front of the carb out of the intake manifold boot.

Pull the rear of the carb out of the airbox boot.

Using the small screwdriver ('03-'05) or the D bit and driver ('06 and up), screw the stock fuel screw in until it bottoms lightly, counting the number of turns of the screw. Try to get 1/4 or 1/8 turn accuracy. Write this number down. It should be from 1/2 to 2 1/2 turns, but, in some cases, it may be more or less than this.

If you have an '06 and up 230F and don't have the D bit and are using some other tool, this will be difficult to do. You can bypass this step, but then you will have to do the "hot" adjustment described below.

Using the small screwdriver ('03-'05) or the D bit and driver ('06 and up), unscrew the stock fuel screw all the way out, being careful to look for the spring, small washer, and tiny o-ring.

In this picture, we are using a toothpick to dislodge the washer and o-ring that remained in the carb after the stock fuel screw was removed.
 
 
 

Do a trial fit of the new extended fuel screw only without the spring, washer, and o-ring. Grease the fuel screw threads very lightly so it will screw easily. Put it in the fuel screw chamber and slide it all the way in using your fingers. When the threads touch, screw it in a few turns using your fingers to get a feel for the action and resistance (minimal). Then, remove the screw.

Lightly grease the o-ring so it's shiny, but no more. This will allow it to seat without causing it to roll up or stick in the chamber.

Install the spring, small washer, and tiny o-ring on the extended fuel screw.
 
 

With the carb slightly tilted from vertical, carefully guide the fuel screw and three small parts into the fuel screw chamber and slide it all the way in using your fingers. When the threads touch, screw it in a few turns using your fingers.

Using your fingers, screw the fuel screw in until it bottoms lightly.

Then, unscrew the extended fuel screw the same number of turns that the stock fuel screw was set at. This is the number you were supposed to write down in the step where you removed the stock fuel screw. If you don't have this number, set the fuel screw to 1 1/2 turns out and do the "hot" adjustment described below.
 
 
 
 
 
 
 
 
 

Insert the back of the carb into the airbox boot. Insert the front of the carb into the intake manifold boot. Make sure the throttle cables don't get kinked or pinched.

Rotate the carb to vertical and make sure that the tab on the front of the carb is aligned with the rubber alignment slot on the intake boot. Tighten the front and rear band screws.

Put the ends of the vent hose and drain hose into their respective frame tabs.

Operate the throttle to make sure that everything works. You should hear a small clunk when the slide hits the bottom of the carb as you roll-off the throttle.

Reinstall the tank and seat if they were removed and go riding.

Start the engine and let it warm up for a few minutes. Ride the bike a few hundred yards to ensure that the engine is warm.

Using your fingers, screw the extended fuel screw in until the engine stumbles. If you bottom the fuel screw, and there is no stumble, the pilot jet is too rich; install one size leaner pilot jet and start over.

Now, turn the fuel screw out until the engine runs the smoothest and highest rpm. You may have to hunt back and forth to find the sweet spot. Turn 1/8 turn at a time and let the engine run for 30-60 seconds to settle in at the new jetting. Once you find the sweet spot, stop the engine. If you unscrewed more than 2 1/2 turns, the pilot jet is too lean; install one size richer pilot jet and start over.

With the engine off, screw the fuel screw in until it bottoms lightly, counting the number of turns of the screw. Try to get 1/4 or 1/8 turn accuracy. Write this number down. It should be from 1/2 to 2 1/2 turns, but in some cases it may be more or less than this. Unscrew the fuel screw the number of turns you wrote down. Go riding.

Refer to Changing the needle and/or adjusting the needle clip above and Detailed carb pictures below to see pictures of the carb internals. The Honda CRF230F Service Manual shows more pictures and is a great help when doing this procedure. The hardest part in the whole job is unscrewing the carb screws, with the slide screws being the hardest. Buy a set of JIS screwdrivers or you'll ruin a lot of screw heads.

Remove the carb from the bike.
Remove the two screws from the top of the carb and remove the carb top.
Remove the small retaining spring and link from the link arm and slide arm.
Remove the slide screws.
Remove the link arm locking screw.
Remove the slide from the carb.
Remove the needle retainer (plus screws) and carefully remove the needle.
Remove the drain bolt on the bottom of the float bowl.
Remove the three screws from the float bowl and then the float bowl.
Remove the plastic baffle.
Remove the pin, float, and float valve.
Remove the pilot jet, main jet, and needle jet holder.
Remove the fuel screw, spring, washer, and o-ring.
Do not remove the air cut-off cover.
Do not remove the air jets in the back of the carb bell.
Clean the carb body and all internal passages.
I use carb cleaner or solvent on a rag and rub/scrub using my fingers.
A tooth brush is also helpful.
Use light air pressure to blow out passages.
Clean the jets, needle, slide, etc.

Look among the parts you have for the following:

Main jet
120  sea level
110  5,000' - 6,000'
108  6,000' - 10,000'
105  above 10,000'

Pilot jet 42

Stock needle '03-'05 16012-KPS-901 marked C39A
Set the clip in the middle position (#3) on the needle.
Adjust as needed.

Aftermarket fuel screw, preferably brass, preferably Kouba.
Set at 1 1/2 turns out and adjust as needed.

These are suggestions for a stock CRF230F. If you have made any engine mods or changes to the intake or exhaust, adjust accordingly.

If you don't have these parts, buy them before proceeding.
-------------------------

Assemble the carb as follows:
Assemble the fuel screw parts: fuel screw, spring, washer, o-ring.
Apply a small dab of grease on the fuel screw o-ring; very small amount.
Screw in the fuel screw until it bottoms lightly, then unscrew 1 1/2 turns out; adjust as needed.
Install the pilot jet, needle jet holder, and main jet.
Install the float valve, float, and pin.
Set the float level to 12.5mm - 13mm.
Install the plastic baffle; align the cutout with the prospective float bowl overflow tube location.
Install the float bowl; three screws.
Install the drain bolt on the bottom of the float bowl.
Install the needle in the slide and cover with the needle retainer (plus screws).
Snug the slide screws, do not tighten now.
Install the slide into the carb.
Tighten the slide screws now.
Install the link and small retaining spring onto the link arm and slide arm.
Install the link arm locking screw.
Install the carb top and the two screws on the top of the carb.
Install the carb on the bike.
Check that the throttle operates the slide and the slide clunks when you release the throttle.

You can buy the fuel screw washer and o-ring separately if you don't want to buy the fuel screw set (above). But note the Honda fuel screw set contains the actual Honda/Keihin parts, whereas, the parts described below are not Honda parts, so there may be very slight discrepancies. Businesses are listed alphabetically.

Apple Rubber

I did not take the time to search out the correct size o-ring on this site, but I did read up on the fascinating variety of materials and sizes that are available. This site is included for information content.

Apple Rubber

Carburetor Parts Warehouse

It's best to call these guys directly. I've never had luck ordering on-line from them. They do have, or can get, the parts you need, in most cases.

Carburetor Parts Warehouse - Keihin PWM Carburetor Parts List
Carburetor Parts Warehouse - Keihin FCR Parts List

Jets R Us

34. O-Ring, Pilot Screw  16075-KG8-9010-M1 (SKU 021-043)  $1.10 ea.

'Kinda expensive, compared to others. Not used/tested yet.

Jets R Us

McMaster-Carr

9263K511  Chemical-Resistant Viton Fluoroelastomer O-Ring, 1 mm Wide, 3 mm ID, Packs of 25  $6.08 per pack

A few friends and I have successfully used 9263K511 o-rings in KTM 4T, CRF230F, and CRF250X carbs using 10 percent ethanol and non-ethanol fuel.

McMaster-Carr

Sudco

I have never ordered from Sudco; I think they sell to dealers only. However, they have some very good carb documentation that you can download. The Sudco catalog can be read on-line and printed, but I've never been able to download a copy.

Sudco

Z1 Enterprises

Washers - Mixture Screw - Keihin SKU: KL18-0055-1  Pack of 25 - $18.25

A few friends and I have successfully used KL18-0055-1 washers in KTM 4T, CRF230F, and CRF250X carbs using 10 percent ethanol and non-ethanol fuel.

Z1 Enterprises

You can buy carb rebuild/repair kits to R&R your carb. The kits have a selection of parts that commonly need replacing, and they cost a fraction of individual OEM parts.

Two aftermarket kits, Outlaw (below, left) and Shindy (center), are virtually identical and priced very reasonably. The kits are often listed on eBay and sometimes on Amazon. I have not used either kit yet.

Honda groups small parts into sets and the combination of two such sets is almost equivalent to each of the aftermarket kits. The Gasket Set (GS) and Screw Set A (SS) parts are shown in the right column.

Parts are identified with numbers that match the OEM equivalents shown in the parts fiche and parts list below.

Note the two o-rings labeled '1b'; each aftermarket kit contains two of these. The combined Honda sets have two 1b o-rings also. I suspect that the aftermarket kits have two 1b o-rings because the combined Honda sets have two of them. Their kit designer apparently did not understand Honda's breakout.

Note that the aftermarket kits do not include a '1c' o-ring, but the Honda Gasket Set has one. The 1c o-ring is not a doughnut-shaped o-ring. It is flat on the bottom, and the cross section shows it taller than its width. Many riders will not want to service the Air cut-off assembly (14 on the fiche) and replace 1c; doing so could damage the diaphragm and a new assembly costs about $80. Best leave that assembly untouched unless you have symptoms indicating it is not working properly. I suspect the aftermarket kit makers left 1c out on purpose.

OEM prices are from DiscountHondaParts.com as of November 7, 2017.

Both aftermarket kits have the same number and kind of parts.

Outlaw Carburetor Rebuild Kit   OR2536   $18
1a Light-weight paper gasket
3b Unmarked needle
31,32 The pilot (42) and main (102) jets are marked with their sizes and the Keihin symbol.
All other parts identical to the Shindy kit.

Shindy Carb Repair Kit   03-720 86030   $29
1a Heavy-duty compressed paper gasket
3b Needle marked D629
31,32 The pilot (42) and main (102) jets are marked with their sizes.

One last consideration. Although the aftermarket kits include main and pilot jets, these come in stock Honda sizes. If you have already changed one or both during your jetting setup, you'll want to stick with the sizes you have. If you want new versions of those jets, purchase them from Jets-R-Us, your dealer, or an on-line vendor.

Purchased from Rocky Mountain ATV/MC on 11/7/17.

Needles are marked with an alphanumeric code that you can barely read with the naked eye.

Stock needle '03-'05  16012-KPS-901  marked C39A
Stock needle '06 and up  16012-KPS-731  marked C83A
Power up needle  16012-KPS-921  marked C30FF

Needles are shown with the fat end up and the tapered tip down. Clip positions are numbered from top to bottom; 1 (top), 2, 3, 4, 5 (bottom). Clip position 1 is the leanest, 3 is usually the stock position, and 5 is the richest. The two-clip-position needle has stock (bottom) and high-altitude (top) positions only.

                    Main  99101-357 series                               Pilot  N424-21 series