XR250R/XR250L Carburetor Notes January 24, 2018 version

Click pictures to supersize.

CONTENTS
   XR250 / XR250R generations
   External similarities
   Cylinder head connection
   Air box connection
   Rebuild Kits - OEM and aftermarket
   Comments

A few observations on the US 1986-2004 XR250R and the 1991-1996 XR250L carburetors.

The purpose of this web page is to provide riders with information to mix-n-match various US XR250R and XR250L carbs and parts. Note that UK and AUS carbs may be similar, but as far as I know, the bikes are road versions and some have electric start. Other countries around the world have a dizzying variety of XR models/carbs. I will be discussing the US carbs only.

US carbs come in 49-state and California (CA) versions and some carbs come in one version only. I will not specifically address the CA versions. The primary difference between the two versions is jetting.

XR250 / XR250R generations

The US XR250L is based on the US 1986-1995 XR250R model.
XR250R Gen 4 and 5 and all XR250L models (91-96) are the focus.
Other XR250 / XR250R years are not considered herein.

Honda was surprisingly consistent using a distinct carb for each Gen 4, Gen 5, and L bike group, as shown below.
PD05, PDG1, and PD79 carbs come in variations determined by jetting component differences.

I have decided to use data from only one carb from each group - the first carb in each group. Subsequent carbs generally have minor changes, mostly jets, and otherwise maintain the same configuration.

XR250R carbs - Gen 4

86-95 are not available from Honda dealers.

XR250R carbs - Gen 5

96 and newer are available from Honda dealers - about $250 and up.

XR250L carbs

91-96 are not available from Honda dealers.

Some carbs are available from aftermarket vendors, on eBay, and from private parties.

External similarities

I have never had the opportunity to hold all 3 carb models in my hands at one time, but I have held each of them at one time or another. I first thought about comparing them when I bought my 1991 XR250L and began to study that bike's carb to see if I could improve it's performance using XRR jetting parts. I was able to physically compare the XRL carb to my 86 XR250R carb and make decisions about parts swapping. As I create this web page, I have NONE of the three carb models available, so I will resort to parts fiche and old notes.

Belay that last remark. Friends have seen to it that I have physical samples of the carbs I'm describing; I will be posting many carb pictures with explanations and observations. Stay tuned....

DISCUSS choke, AP, inlet, outlet, length, height, width.
Jets are chosen by vendors, and are not necessarily the sizes you should use. Jetting is dependent on riding elevation, temperature, humidity, and the state of engine tune (performance modifications).

Cylinder head connection

The first item of note is the carb insulator, which connects the carb to the cylinder head: it is identical between all three carbs.
The o-rings are identical, also.

The mounting bolts differ, as well as the metal bands and bolts.

The evidence suggests that the three carb models have identical fronts. All three are PD variants, and this supports the conclusion.

Honda part numbers are shown in the table below.

Air box connection

The air box connecting tube front opening fastens to the back of the carb, and the band clamp size reveals the size of the back of the carb bell.

86-95 XR250R A AIR CLEANER
BAND, AIR CLEANER CONNECTING TUBE (52)  90652-GHB-690  95018-52250
  ↑ same ↓
91-96 XR250L A AIR CLEANER
BAND, AIR CLEANER CONNECTING TUBE (52)  90652-GHB-690  95018-52250
  ↑ different ↓
96-04 XR250R A AIR CLEANER (A)
BAND, AIR CLEANER CONNECTING TUBE (60)  90652-GHB-730  95018-60250

Honda part numbers for parts shown above are listed in the table.

Stock Honda part numbers from:
Dillon Brothers Motor Sports - partsfish.com      Partzilla - partzilla.com

Rebuild Kits - OEM and aftermarket

OEM kits

Honda groups some carb parts into sets; other parts are listed individually. These sets make do as rebuild/repair kits. I show the Gasket Sets for the three carbs of interest.

86-95 XR250R GASKET SET 16010-434-305  $22.18 RMAM (Rocky Mountain ATV/MC)
96-04 XR250R GASKET SET 16010-KCE-670  $21.74 RMAM
91-96 XR250L GASKET SET 16010-KR6-305  $23.01 RMAM

The parts are keyed to these tables ↓ and the fiche shown in the aftermarket kits section below.

The XR250R carb Gasket Sets are identical; the XR250L carb Gasket Set differs slightly due to the accelerator pump and the absence of a float bowl bottom bolt and air cut-off. You can see a list of the other sets by looking at the comprehensive master spreadsheet near the bottom of the web page.

Aftermarket kits

There are several vendors who offer carb repair or carb rebuild kits at prices substantially less than the corresponding Honda OEM sets and parts. These kits are actually an aggregation of several Honda OEM sets into one package. A few Honda OEM parts are not represented in the aftermarket kits.

These kits are similar to each other, differing in regards to the accelerator pump etc just as the OEM Gasket Sets differ.

Most parts in these kits are of acceptable quality, with the notable exception of the fuel screws, needles, main jets, and pilot jets. The fuel screws are identical to the early OEM fuel screws, and they are really too short. A longer aftermarket fuel screw is much better. I did not measure the needles to compare them to the OEM needles. They are a very light weight brass or alloy and I don't trust them; I prefer OEM needles. The same goes for the jets; I prefer OEM Keihin jets, available from Honda dealers or JetsRUs.

Shindy carb rebuild/repair kit XR250R 1986-95 - 03-734  $21 eBay  $24 RMAM

The aftermarket parts in the Shindy rebuild kit (left picture just below) are keyed to stock Honda parts shown in the table and fiche. The parts break-out shows parts in each Honda set. Honda does not uniquely number each part in a set, but I have numbered these parts so they can be located on the fiche.

↓ Honda sets - parts break-out   1986 XR250R   1 GASKET SET 16010-434-305 1a Float bowl gasket   1b Float bowl bottom bolt o-ring   1c Float bowl drain screw o-ring   1d Fuel screw o-ring   1e Top gasket   1f Air cut-off o-ring   2 VALVE SET, FLOAT 16011-KG0-891 2 Float needle and bail   3 NEEDLE SET, JET 16012-KA6-004 3a Needle jet   3b Needle clip   3c Needle, 5 position  D700   6 CHAMBER SET, FLOAT 16015-KA6-004 6f Float bowl drain screw   7 SCREW SET A 16016-385-681 7b Fuel screw washer   7c Fuel screw spring   7d Fuel screw   31 JET, MAIN #125 99101-357-1250 31 Main jet, 125  no logo   32 JET, SLOW #40 99103-437-0400 32 Slow jet, 40  no logo

Shindy carb rebuild/repair kit XR250R 1996-04 - 03-735  $22 eBay  $24 RMAM

The aftermarket parts in the Shindy rebuild kit (left picture just below) are keyed to stock Honda parts shown in the table and fiche. The parts break-out shows parts in each Honda set. Honda does not uniquely number each part in a set, but I have numbered these parts so they can be located on the fiche.

↓ Honda sets - parts break-out   1996 XR250R   1 GASKET SET 16010-KCE-670 1a Float bowl gasket   1b Float bowl bottom bolt o-ring   1c Float bowl drain screw o-ring   1d Fuel screw o-ring   1e Top gasket   1f Air cut-off o-ring   2 VALVE SET, FLOAT 16011-KCK-910 2 Float needle and bail   3 NEEDLE SET, JET 16012-KCE-670 3a Needle jet   3b Needle clip   3c Needle, 5 position D701   6 CHAMBER SET, FLOAT 16015-KCE-671 6f Float bowl drain screw   7 SCREW SET A 16016-402-004 7b Fuel screw washer   7c Fuel screw spring   7d Fuel screw   32 JET, SLOW 45 99103-KPS-0450 32 Slow jet, 45  no logo   33 JET, MAIN 132 99113-GHB-1320 33 Main jet, 132  no logo

Keyster carb repair/rebuild kit XR250L 1991 - KH1066NA  $38 eBay

The aftermarket parts in the Keyster rebuild kit (left picture just below) are keyed to stock Honda parts shown in the table and fiche below. The parts break-out shows parts in each Honda set. Honda does not uniquely number each part in a set, but I have numbered these parts so they can be located on the fiche.

↓ Honda sets - parts break-out   1991 XR250L   1 GASKET SET 16010-KR6-305 1a Float bowl gasket   1c Float bowl drain screw o-ring   1d Fuel screw o-ring   1e Top gasket   1g Air cut-off base o-ring   1h Float bowl rod o-ring   1i Accelerator pump rod o-ring   2 NEEDLE SET, JET 16012-KV6-671 2a Needle jet   2b Needle clip   2c Needle, 1 position D344   6 SCREW SET A 16016-KC2-970 6a Fuel screw washer   6b Fuel screw spring   6c Fuel screw   13 VALVE, FLOAT 16155-413-751 13 Float needle, short, no wire bail   14 HOLDER, NEEDLE JET 16165-473-004 14 Needle jet holder   35 JET, MAIN #122 99101-GHB-1220 35 Main jet, 122  no logo   36 JET, SLOW #38 99103-KV6-0380 36 Slow jet, 38  no logo

A picture of all three rebuild kits showing all parts at a glance so differences can be easily seen.

Rebuild/repair kit summary

The similarities between kits, with the notable exception of the accelerator pump on the 250L, indicates how interchangeable these carbs and their parts are.

When I modified the carb on my XR250L, I wrote:

The accelerator pump carb on the XR-L looks like it has potential. Pumper carbs can be jetted to get rid of that nasty four-stroke hesitation on the bottom and give good power on top too. However, the non-pumper carb from the XR is ultimately a better performer because it is designed for more air/gas flow. The needle and seat on the pumper carb are designed to make the bike EPA legal (lean) and are the biggest impediment to performance.

Where I wrote 'needle and seat' I should have written 'needle, fuel screw, main jet, and pilot jet' because these items collectively limit the carb's performance so it conforms to EPA standards. I suspect that changing the needle to an XR250R needle would provide a significant improvement in performance. Getting the jets correct for your riding elevation and setting the fuel screw for optimal off-idle pickup would be the final tuning steps necessary for best performance. Setting up the accelerator pump would be the icing on the cake. I actually think a correctly set up XR250L carb would be the perfect carb to install on 86-95 XR250R bikes.

I plan to set up a 250L carb for a local XR250R rider, and will post up results when they are available.

A picture of the master spreadsheet showing all carbs parts at a glance so differences can be easily detected. The lower case 'd' in columns D, H, and L indicate part number differences. Although there are instances where Honda has changed a part number and the new and old parts are actually the same, it's more often the case that different part numbers means different parts.

Comments

When the 1991 XR250L arrived, many of us saw it as a derivative and extension of the XR250R Gen 4 line that began with the long-stroke 1986 engine. As we delved into the XRL, we saw that it was just an XRR with street-legal additions (lights, horn, battery), and we knew the path from a street-legal XRL to a more dirt-oriented XRL could be facilitated by the simple replacement of XRL parts with aftermarket-improved XRR parts.

When the 1996 XR250R was studied, it was clear that it was a next-gen bike, and moving parts from this newer model to the XRL might not be so easy or productive.

All of this is to say that it is important to mention the YEAR and MODEL when talking about which parts crossover.

- fini -