Replacement Carb?

[MXonaKawi]

I was thinking about buying a replacement carb on ebay brand new. My 00' KX 125 uses a Mikuni TMX35. The original seemed to work fine before I took the bike apart and the previous owner told me that he had just rebuilt it. But it's scratched (i know thats a silly reason but I want everything to have that showroom shine on this rebuild) and since it's a pretty important part, I figured I can't go wrong for $150 for a brand new one that I can jet to my ideal settings with no scratches. What are your thoughts?

[don46]

I'm pretty sure, like almost poitive that the 00 kx125 used a kehin carb, I don't think they went to the Mikuni till 03. In 03 they did not use the TPS or power jet, from 99-02 they did

[KevinTwoStk]

I have an '00 KX 125, so I can say for sure that it comes with a Keihin PWK Power Jet carb.

I believe the '01 and '02 models came with Mikuni TMX carburetors--check out JD Jetting's website to find out for sure.

My experience with the PWK Power Jet carburetor has been good so far. I don't see any reason to swap it out. Once I found the right jetting, I haven't had to mess with it. The jetting's "sweet spot" seems to cover quite a range of altitudes and weather conditions.

[MXonaKawi]

I have an '00 KX 125, so I can say for sure that it comes with a Keihin PWK Power Jet carb.

I believe the '01 and '02 models came with Mikuni TMX carburetors--check out JD Jetting's website to find out for sure.

My experience with the PWK Power Jet carburetor has been good so far. I don't see any reason to swap it out. Once I found the right jetting, I haven't had to mess with it. The jetting's "sweet spot" seems to cover quite a range of altitudes and weather conditions.

Hmmmm interesting. I mean who knows what was done in the 13 years before I had it. But when I got it, it had the mikuni. I found some recommended jetting from motocross action mag for my bike so thats how i'm planning on jetting it. Except I'm going to jet down the main jet because I am putting a boyesen rad valve on there and that is what all the reviews said to do for it.
Keep in mind I haven't ridden in 10 years and haven't ridden this bike yet and won't ride it until the rebuild is complete and back together so it's not like I have any settings yet. I need to figure out the settings in order to get it going then I can dial them in from there to preference.

[KevinTwoStk]

I only read one jetting recommendation from Motocross Action for the 2000 KX 125, and it had to do with the Keihin PWK. You may have read the same one. Keep in mind that if you have a Mikuni, the main jet numbers are going to be completely different.

So if you've got a Mikuni TMX, you might do well to get a JD Jetting kit for an '01-'02 KX 125, since that's quite likely what the Mikuni could be from. I would double-check the bore size and the slide number to make sure that you've got a KX 125-spec carb.

Besides JD Jetting, Sudco is a great resource for carburetor parts and expertise.

It sounds like you're in a similar place to where I was, being off the bike for an extended period and then doing a rebuild before beginning to ride again. I went through my bike pretty thoroughly (thoroughly--not completely) before I rode it, and the effort was worth the trouble. It's been very reliable, and I've since been busy improving the performance little by little.

When's your first ride? Do you have a race or an event you're working toward?

[don46]

looked on the fiche, mikuni came in 01, Kehin up to 00

[MXonaKawi]

I only read one jetting recommendation from Motocross Action for the 2000 KX 125, and it had to do with the Keihin PWK. You may have read the same one. Keep in mind that if you have a Mikuni, the main jet numbers are going to be completely different.

So if you've got a Mikuni TMX, you might do well to get a JD Jetting kit for an '01-'02 KX 125, since that's quite likely what the Mikuni could be from. I would double-check the bore size and the slide number to make sure that you've got a KX 125-spec carb.

Besides JD Jetting, Sudco is a great resource for carburetor parts and expertise.

It sounds like you're in a similar place to where I was, being off the bike for an extended period and then doing a rebuild before beginning to ride again. I went through my bike pretty thoroughly (thoroughly--not completely) before I rode it, and the effort was worth the trouble. It's been very reliable, and I've since been busy improving the performance little by little.

When's your first ride? Do you have a race or an event you're working toward?

Yea I have never ridden the bike, only started it. I am not planning on racing it. I just plan on riding at tracks and racing against my own lap times haha. But when I'm out there I'll be the MX announcer in my helmet and Carmichael will be right behind me, gaining on me each lap! Haha. I am going through every part of the bike and replacing every bolt and many of the parts. I love the 99-02 KX 125's and they obv don't make them anymore. So I figured I could build a 90% brand new one that will last me about 6 or 7 maybe more years. Glad to hear that the effort is worth the trouble. I know it will be worth the elbow grease when it's done and the process is exciting. it's like Xmas every time I get a new part in the mail. First ride will probably be early 2014 at the soonest. I am going to get an enclosed trailer, and make it my bike shop inside and also keep the bike in there as well as transport it. It's going to take a bit to get everything all sorted out, but it will be worth it when it's done.

As for the carb, I think I want to start with a brand new one and start from a clean slate. Now the only question is...do I get the Keihin stock one or another Mikuni TMX?

[KevinTwoStk]

If you have the wiring harness to support the Keihin then that carb makes a lot of sense. If not, I'd say go with the Mikuni.

For the electronic version of the Keihin PWK to work correctly, you should have a connection for the throttle position sensor (TPS) and for the Power Jet solenoid.

I've had really good luck with my Keihin PWK, although I did have to change the jetting from what was in the manual. I have heard the Mikuni TMX is harder to jet correctly, but I haven't had personal experience with this.

I saw your rebuild thread--the bike looks good!

[MXonaKawi]

If you have the wiring harness to support the Keihin then that carb makes a lot of sense. If not, I'd say go with the Mikuni.

For the electronic version of the Keihin PWK to work correctly, you should have a connection for the throttle position sensor (TPS) and for the Power Jet solenoid.

I've had really good luck with my Keihin PWK, although I did have to change the jetting from what was in the manual. I have heard the Mikuni TMX is harder to jet correctly, but I haven't had personal experience with this.

I saw your rebuild thread--the bike looks good!

Thanks man!

[MXonaKawi]

Ok so the stock 2000 KX 125 Carb is a Keihin but which model is it? Is it the PWK36? I'm guessing the jetting I have written down from the old MXA article is for this carb, and since I've heard that Keihin's are easier to jet, this might be my best bet. I can sell my Mikuni TMX35 on ebay and get a brand new Keihin. However, it's $230 brand new on ebay and the Mikuni TMX35 is $150 brand new on ebay. I'm wondering if I should save $80 bucks and figure out the jetting on my own with the Mikuni lol.

Thoughts?

My dilemma is #1 - price and #2 - they obviously switched to the TMX in 01' for a reason and there was a problem with the jetting in 00', but does a problem with the jetting mean a problem with the carb? Not really right? You can always adjust the jetting, correct?

Help!

[KevinTwoStk]

It's worth noting that Kawasaki used the Keihin Power Jet carb on the KX 250 two-stroke all the way up to 2007.

I'm not sure why the carb brand switch was made in 2001.

Do you have the wiring/sensor connections to support the Keihin Power Jet carb? You probably do, but should make sure before buying a Keihin Power Jet carb.

The model is the Keihin PWK36S.

Here are my jetting specs:

158 main
42 power jet
N7NW needle (stock) in second clip from the top
40 pilot jet
Air screw adjustment is about two turns out.

I am in SoCal and ride between roughly sea level (Ocotillo Wells) and 5,000 feet (Cajon Pass area).

Fuel is 100 octane race gas (available at the pump at selected stations) mixed at 32:1 with Maxima Super M.

So that's one base line which may help you...your jetting may vary  .

[Charlie500]

It's worth noting that Kawasaki used the Keihin Power Jet carb on the KX 250 two-stroke all the way up to 2007.

I'm not sure why the carb brand switch was made in 2001.

Do you have the wiring/sensor connections to support the Keihin Power Jet carb? You probably do, but should make sure before buying a Keihin Power Jet carb.

The model is the Keihin PWK36S.

Here are my jetting specs:

158 main
42 power jet
N7NW needle (stock) in second clip from the top
40 pilot jet
Air screw adjustment is about two turns out.

I am in SoCal and ride between roughly sea level (Ocotillo Wells) and 5,000 feet (Cajon Pass area).

Fuel is 100 octane race gas (available at the pump at selected stations) mixed at 32:1 with Maxima Super M.

So that's one base line which may help you...your jetting may vary  .

How come your running a 42 power jet? Stock is 50 I think right?

[KevinTwoStk]

The 42 power jet was recommended by Motocross Action, so I changed that right off the bat.

The other specs listed are mine based on the ride-and-feel method (aka trial and error) but oddly enough they coincide with the Australian model 2000 KX 125. European, U.S., and Australian specs are listed in the factory service manual.

[MXonaKawi]

It's worth noting that Kawasaki used the Keihin Power Jet carb on the KX 250 two-stroke all the way up to 2007.

I'm not sure why the carb brand switch was made in 2001.

Do you have the wiring/sensor connections to support the Keihin Power Jet carb? You probably do, but should make sure before buying a Keihin Power Jet carb.

The model is the Keihin PWK36S.

Here are my jetting specs:

158 main
42 power jet
N7NW needle (stock) in second clip from the top
40 pilot jet
Air screw adjustment is about two turns out.

I am in SoCal and ride between roughly sea level (Ocotillo Wells) and 5,000 feet (Cajon Pass area).

Fuel is 100 octane race gas (available at the pump at selected stations) mixed at 32:1 with Maxima Super M.

So that's one base line which may help you...your jetting may vary  .

Hey man thanks a million for this info. I am in SoCal too and I will mostly ride tracks like Milestone, Piru, Gorman, Motoplex, Pala, Perris, Racetown 395 etc. Can you snap a quick pic of the wiring/sensor connections? I'm not sure if I have them.

I will most likely run 100 octane gas as well if I can find it. I live in Studio City. I am going to run Klotz Benol. Should I mix 32:1 as well?

[KevinTwoStk]

Here's a link for race gas at the pump:

http://www.davebarton.com/Unleaded_Racing_Fuel_in_SoCal

I have bought race gas from Arroyo Parkway Union 76 in Pasadena and at Mark's Union 76 in Fullerton. Both of those stations are listed on Dave Barton's site. I'm not sure about the others listed.

Yes, definitely mix at 32:1. If you choose a different mixing ratio none of the listed jetting specs will apply.

I'll get that photo for you later on tonight.