'04 CR125 Anyone have one that runs well with stock jetting

[Texas125]

Have '04CR125 and have had plug fouling problems at low rpms since start. Stock slow jet is 40. Changed to 37.5, opened air screw 3.5 turns and reduced mix from 32:1 to 40:1 with some success. Currently heading to pick up 35 and 32.5 slow jet to check out but was wanting to know if anyone has had any luck with the stock 40 or 37.5 slow jet. In Dallas so 600 feet and ~70F. Problem occured even at 40F.

[Faded]

Originally posted by Texas125
...reduced mix from 32:1 to 40:1...

By reducing the amount of oil per volume you've effectively added more fuel/gas to the air/fuel mixture. You've taken two steps forward and one back.

If you're airscrew is still at 3.5 turns out with the 37.5 pilot you'll need to trade the pilot out for the next leaner pilot (#35) and try that. You want to get your airscrew adjustment between 1 and 2-1/2 turns out. Less than one signals a lean pilot, more than 2-1/2 and the pilot is too rich. Good luck.

[Texas125]

You make a good point on the lowering the mix ratio. I've been getting desparate just to keep it from fouling on the line. I't been a long road on this one, many basic factory problems, ie burrs in needle tube, float not being adjusted, etc. I was heading in the direction of the leaner slow jet but have never had to go that far from stock settings according to the manual on any Honda bike that I've had. I'd like to figure out if the Honda boys have too much Sake when they chose the jetting on the '04 or what. The '03 runs a 30 slow jet but I've been told that the '04 is a different carb setup. With the '04 250 running a 32.5 stock slow jet, I'm begining to wonder about Honda's QC program these days.

[Faded]

Sorry to hear about your problems. My float wasn't set on mine either, close but not correct. Most of the people I've talked with are running 30 pilots on thier 03/04 250's along with smaller straight section needles (richer @ off idle to about 1/4).

It would be interesting to find out exactly what differences there are between the 03/04 125 carbs. If they're the same size/brand and the slide cutaway is the same then the porting differences would have to be drastic to change intake velocity at smaller throttle openings. Don't worry, I've heard of similiar problems with the KX125's, thier pilot jets seem to be 2 to 3 sizes too rich as well. I would stick to what the bike tells you IMHO.

[Texas125]

Thanks for the input! It's good to hear that other bikes have the same issue. It's been my experience that when your start getting too far off stock settings there is generally something else wrong. It just was not working out that way this time, not with a new bike. Will let you know what I find out on the leaner slow jets. Thinking that once I have it running good I'll take it to a local Dyno to find out where it really is on the scale.

[smithers]

Originally posted by Texas125
I'd like to figure out if the Honda boys have too much Sake when they chose the jetting on the '04 or what. I'm begining to wonder about Honda's QC program these days.

As Faded and the rest know, My kids '03 is wack also...spluges all over itself...I had the carb apart 30 times for re-jetting, needle placement and replacement, float adjustments....I finally gave up as nothing changes the problem...I will dive back into it some day soon when im bored...just wanted to let you know you're not alone.

[Faded]

Originally posted by Texas125
...It's been my experience that when your start getting too far off stock settings there is generally something else wrong...

Speaking from experience, I'd really start to worry when you need to richen things up vs. leaning them out. Don't ask how I know.

Originally posted by smithers
...I will dive back into it some day soon when im bored...

Let me know when that time comes S-dawg, I will be more than happy to help if I can.

[Texas125]

Could it be similar to the time I misread the main jet and put in a 165 instead of a 185? You must have heard the dreaded "Sound of Silence" also?

[Faded]

It never went that far. I have had it knocking like an army of bill collectors at the door though...something to do with broken reeds and a leaky crank seal.

[rmyers]

I have an 04 CR125 purchased about 3 weeks ago and I have gone through at 12 plugs. I just heard from a parts guy at the local honda shop that he overheard some mx guys talking about the 04 stock jetting being completely off but unfortunately he could not give me any details. When I returned to the dealership where I purchased the bike, I was given a bag of new jets without asking for them. Is this common with the purchase of a new CR125.

The confusing part is that I am getting different results after checking the plug coloration from day to day. For example after riding at the track, made minor adjustments to the air screw and plug color looked fine.

Two days later the plug fouled immediately on starting. Then I made adjustments to the needle clip position based upon information from another forum and checked the plug, it was too lean, so I turned the air screw in and rewrode then rechecked. Plug looked great. Next day it fouled immediately on startup and would barely run with a new plug. Although it was refueled on this day, the fuel was from the same gas can so I am positive the mixture was correct.

The end result is this has become a very confusing situation because results are changing daily even though no adjustments are made between rides?

Can anyone else confirm problems with stock jetting on an 04 CR125

Thanks
Ron

[Thump_This]

shoulda bout another color bike. j/k. i couldnt resist. i have heard the same things being discussed in this thread ALOT lately. when i was at Chapparal this morning i was speaking with a friend of mine that works there about the 04 and upcoming 05 bikes. he said out of ALL of the bikes Chapparal sells they cannot move the 04 CR125 even when selling it at almost cost. he said people just arent interested in the CR125 when they can buy a CRF250R for just a little more money. he also said that they have been notorius for jetting related issues and the reeds are junk on the 04's so you might wanna make sure your reeds are ok. he recommended that you attempt to use the same jetting as the 03 models had. he also said there arent any considerable differences in the 04 carb. thats just what i heard though. might wanna give them a call and they can help you further.

[Faded]

Ron,

I would first and foremost start with setting/verifying the float level before going any further. Also, where are your airscrew settings ending up? If you're more than 2.5 turns out and you're fouling on start-up then I would suspect that your pilot jet it too rich and needs to be stepped down a notch. This can affect the transition to the needle and may require a needle with a smaller straight section (affecting 1/4 throttle) or a needle clip position change (1/2 throttle) if you end up on the lean side after swapping pilots. Checking the plug isn't much good unless you're wanting to see main jet strength. After you get the pilot/air screw set do some roll on throttle tests from 0 to 1/4 and 1/4 to 1/2 and make adjustments as neccessary (bog=lean). Good luck.

[Texas125]

MMMM! Sounds like there is a consist message here. Do you think the Honda Engineers were smoking too much rice paper again when they did the jetting?

Well, I am proud to say that progress is being made. Not there yet but getting closer. First of all, the original jetting in the bike and the Owner's manual is certifiably wacked out. The service manual gives stock jetting much closer to the '03 and seems to be a better fit. Here's the poop on my learning curve.

1) Change the 40 slow jet to a 30 and your plug will stop fouling.
2) Change the 26-69 needle to a 21-69 and your getting closer to what it needs to be. I am on the first clip position on the 21-69 and running OK at 70-80F. Ran OK on the first clip 26-69 when it was in the 40F's but blubbered after that as it warmed up.
3) The stock main jet should be a 430. The 420 was almost too lean at 55-60F. Then get various increments of 10 to cover your jetting changes for temp and altitude, checking the plug to see where you are.
4) All above at ~600ft above sealevel.

So, slowjet good, main jet good! Now for the needle. Being on the first clip, I'm going to have to do something to get leaner when the warmer weather comes. Will update you on this progress as it comes. At sometime, I need to find the time to go put the bike on the dyno to see where I am.

Hope this helps!

[Faded]

Texas, what is the full name of the needle? I.E. my 250 was 6BEY30-74. Thanks.

[Texas125]

Andrew,
My memory is not that good so called the dealer! The wacked out stock needle was a 6DGY26-69 and the shop manual stock was 6DGY21-69. I've ordered a 6DGY21-70 and 71 to see if it will lean it out enough to be able to drop the clip position.

By the way, the dealer was doing a "brain suck" on me because he's been inundated with the same jetting problems from other owners and couldn't find any help himself.

Hope this helps!

[Thump_This]

yeah. that sake will get you every time. maybe it was a ploy, for Honda to force red riders to buy the CRF250 LOL.

[rmyers]

One of my questions may have been buried in the original message but I asked if it is common when purchasing a new CR to be given an extra set of different sized jets?

BTW.....I almost considered a different color bike as long as it wasn't a green one! After ruining a perfectly good bike because they (TEAM GREEN) couldn't properly engineer a 30.00 idler gear, I will never buy another green bike again!

ROn

[Faded]

Originally posted by rmyers
One of my questions may have been buried in the original message but I asked if it is common when purchasing a new CR to be given an extra set of different sized jets?

FWIW, my 250 came with one needle and one main jet both one step richer than what was installed. I think the your dealer threw you a bag of jets to keep you quite, free stuff usually gives a person that good feeling for while....

I think you're experiencing the Mikuni sydrome associated with these later model CR's. I think the exactness provided by the Mikuni make them super finiky and hard to dial. Just my $0.02

[MICD]

Hey first off don't be so negative with the honda guys.
Hondas are set up for sea level at 80f riding from the factory. If you have any prior experience tuning this should be a no brainer. There is a set up guide for your area of riding in the back of the manual. It almost sounds like a put down on honda the way you phrased your thread.Could be need help tuning my 04 honda anyone willing to help.I think with the threads posted prior to mine will help fine I just had to put in my two cents worth.Good choice on the bike though good luck.03 crf450 here. No complaints.Second note:When ever you buy a brand new bike allways ride it for atleast 45 min to hour then tear it down all the way to the frame.You will find extra material on the intake and inside your carb that can be cleaned up rather easy. Use your red honda locktight only on three threads and put everything back together.Honda builds great bikes but the final assembly can sometimes be alot to be desired.I found nearly nothing for grease in my headset and in my swing arm links from factory.Ride your bike just enough for everything to set itself then take it apart to make sure everything sets in the right manner.ATM is awsome for tunig tips and related problems so keep on posting just watch putting down your bike other honda guys such as myself don't appreciate it and sounds bad coming from a owner such as you.good luck.

[Faded]

Originally posted by Texas125
Andrew,
My memory is not that good so called the dealer! The wacked out stock needle was a 6DGY26-69 and the shop manual stock was 6DGY21-69. I've ordered a 6DGY21-70 and 71 to see if it will lean it out enough to be able to drop the clip position.

Hmmm, that is a big change from the 'stock' needle vs. the shop manual needle. They really moved the postion of where the taper starts. By going to a -70 or -71 you're really only changing the straight section which will have the greatest impact @ 1/4 throttle. If you're trying to dial 1/2 use the clip position...