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HELP. 06 cr125 fouling plugs not jetting related

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Here is the deal.

I bought a new 06 cr 125 that has 16 hrs on it and it has never ran right. I have jetted the bike to pro curcuit specs and the plug is a perfect golden brown when i check it after riding. My problem is; after i take a break from riding and go to start it the plug will foul. Then the plug is covered with gas. I have tried everything from reving the bike up on stut down. Not reving. turning the petcock off. Its like there is fuel pouring into the cyclinder when the bike sits from anywhere from 5mins to 20mins. I called my local shop and they said to check the floats in the carb. I really don't think its a jetting issue. The bike runs great and has never fouled a plug while riding, just on start up. Has anyone ever had this problem before? Any ideas. Thanks for your time.....

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The float has nothing to do with jetting, is has to do with how much fuel goes into the bowl. Is the petcock working correctly? Does gas still fill the bowl when the petcock is turned off? Generally if the float level is off, either not enough gas enters the bowl, or it overflows and runs out the carb overflow tube.

So, after it sits, it won't start, or it starts then fouls? Generally, the pilot jet is the culprit with starting and low rpm's. Maybe check the reeds for the heck of it, they cause a lot of problems if they are out of sorts.

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my 05 cr125 does the same thing. after it's warmed up you go to start it and it doesn't want to start . . . that is, if you don't give it any throttle.

At first i thought it was flooding itself if it didn't start on the first kick, the plug would be wet, so that was my conclusion also. But after maybe the 3rd time of pulling the plug and just trying to unflood the bike i figured out all it needed was some throttle while kicking. Now it starts first kick eveytime.

This really is a jetting/idle adjustment issue, but i just leave mine alone since i have almost zero spooge and the bike performs well.

Kc: the float height effects all jetting circuits.

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After the bike sits for 5 -20 mins, it will always start. It's after i ride 100ft or so it will foul. To me it seems like extra fuel is getting in the cylinder when it sits and then it fouls trying to burn off the extra fuel. I can tell when its fouling and i can hold it wide open or not, and the bike will still foul. After researching Could this have anything to so with it?

UPDATE!! I just got off the phone with a honda customer service rep and after getting involved with a district manager the problem is linked to a faulty seal that is leaking oil from the transmission. The district manager admitted that this was a problem from the factory on the 06 cr 125's.

And I'm happy to announce that all costs for repair with be made BY HONDA.

As I said before and I honestly believe, when you buy a brand new bike it SHOULD RUN. BOTTOM LINE!!! I can understand if I have to make minor adjustments. But, I should not have to rip apart carbs and motors just to get a brand new bike to run. I dont care if the bike comes with a warranty or not. And the big brass at honda agree with me.

Now I just have to wait for the mechanics to fix the bike and I'll be out bustin berm's.

Thanks for all the input.

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Nice :bonk:

I figured with a tan plug it was just something simple.

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FYI

Could this be my problem? I found this infromation on another post. Im going to call my local dealer Tuesday.

UPDATE!! I just got off the phone with a honda customer service rep and after getting involved with a district manager the problem is linked to a faulty seal that is leaking oil from the transmission. The district manager admitted that this was a problem from the factory on the 06 cr 125's.

And I'm happy to announce that all costs for repair with be made BY HONDA.

As I said before and I honestly believe, when you buy a brand new bike it SHOULD RUN. BOTTOM LINE!!! I can understand if I have to make minor adjustments. But, I should not have to rip apart carbs and motors just to get a brand new bike to run. I dont care if the bike comes with a warranty or not. And the big brass at honda agree with me.

Now I just have to wait for the mechanics to fix the bike and I'll be out bustin berm's.

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I called my local dealership and told them what was going on, and they said "dirtbikes don't come with a warranty". So now im stuck with a $4000 bike that runs when it wants to. If anyone knows where i should start troubleshooting please let me know.

Fyi. I did drain my trans oil and it didn't use any oil in 4hrs ride time. If it was the crank seal shouldn't the oil level be lower?

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Yes, if the seal is leaking there should be oil loss, but it could be hard to tell with oil that stays in the bike while draining and adding and stuff. I've read that you can stick the crankcase breather tube in a cup of water and rev the bike, if you get air bubbles that means at least one of the crank seals are leaking.

Search TT for right hand crank seal replacement or something along those lines and you'll find several threads about it. It really isn't a big project to replace the seals, they can be replaced without splitting the cases.

Jetting would be your other solution, and most likely the problem. There's a very good sticky in the yamaha 2 stroke forum under the FAQs that'll tell you everything you need to know to get it worked out.

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Hey I had the same problem with our 07 cr125........If you aren't losing oil in the case which I you probally aren't then your problem is with the carb and the reeds...The reeds are plastic and they suck and the carb is a piece of crap also.....Use a boysen rad valve and get a keihin pwk air striker carb from JD jetting it comes with his kit already installed and ready to go.........If not you will be unhappy with this bike and want to sell it....honestly Honda quality went out the window on this bike...I couldn't be happier with this bike now it really rocks.....

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Hi,

I had the same problems with the plugs also on my 06 CR 125,

I did a lot on the carb and now it works fine but not well.

I never use the choke because if i do so and then try to warm up the

engine by using 1/4 to 1/2 throttle the plug will immediately lost his funktion.

Without choke the engine sounds pretty lean...

So the many things i did on the carb with many different floats in bowl ,jets,needle...,

says me that is perhaps not the real problem.

So for me comes the question, if there is a leak in the crankcase, where is it?

Is it a crank seal or the middle seal of the engine case?

May be you know more right now.

Thanks

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Sounds like the inlet valve in the carb is sticking open.

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Sounds like a simple jetting issue to me. Try leaning out your air screw 1/4 turn at a time and if it doesn't make a significant difference after you are 2.5 turns out then go to the next leaner pilot jet. Pro circuit jetting specs are still a bit rich in my experience.

Other more serious things to try if this doesn't work are... check your compression, low compression can cause rich symptoms.. and check your squish clearance, large squish needs excessively rich mixture to avoid detonation but in turn this leads to fouled plugs.

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I got the same problem on my 07 and its really pissing me off. I checked everything, clean air filter. fresh fuel and 50:1 ratio. reeds look great, float height at 8mm. 27.5 pilot, 410 main, leaner 28-69 needle on 2nd clip postion. started it up tonite and poof ! fouled the plug ! I don't get it ? too rich still. because it still starts with no choke. That just don't seem rite. Any help would be so awsome !

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Hondude450, try a fuel ratio of 32:1, it'll lean it out a little as far as the amount of fuel in the mix. Make sure that you aren't loosing trans oil. i'm not familiar with your area's conditions, but a 27.5 pilot seems extremely lean. How's your plug looking?

What's working for me and my '05 (right above sea level and temps between 80*f and 100*f):

Honda hp2 or castor 927 premix mixed at 32:1

45 pilot, stock needle 2nd clip, and 410 main

No-toil filter and fmf sst with shorty

Edited by honda53

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Thats whats pissing me off. is the bike ran good and no plug fouling earlier this week. plug looked ok. not wet. clean and brown color. started it up today and the same damn thing as before. go to warm it up starts no choke ? idles fine. ride it around. too start cleaning it out, ok. then i stop, rev it up and plug fouling begins. none of my other bike do this. I have an 03 CR 250 with stock jetting and NEVER fouled a plug. if stock is 55 and iam at a 27.5 and its still to rich ?? I have alot of bikes and the they all a jetted properly, and they need the choke to start cold. even in high temps that why I feel the pilot is still to rich. Iam in central PA. temp 70-90 and 300ft above sea level. bumping up the oil ratio is still hiding the rich jetting just like a hotter plug IMO. if it was burning gear oil I would smell it. I don't think thats the issue here.

Edited by Hondude450
forgot a few details

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sea level

run an 8 plug

28/69 needle

do not lean the pilot less than 45 too big a transition from pilot to straight section will result in fouled plugs

2nd clip position summer, 3 rd winter

430 main, 440 winter

dont fall for 32:1 crap internet people feed you. A quality oil like motul 800 will easily go 50:1 in a 125. i started at 40:1 playing it safe and gone to 45:1 with that jetting but if i went to 50 those specs would require a change. But i will be doing that in the near future. The big gap 125 world record holder runs 50:1 all day in that bike with no problem with motul 800.

those settings sound rich dont they, never fouled a plug and i ride ST. Only gripe would be the tmx38 carb is sensitive to air screw adjustments, 1/4 usually settles that but it is a pain sometimes. But the bike makes great power. Aussie fuel is different 98 octane i'm running but i believe there is a difference between ron and mon, sort that yourself

edit, i believe someone mentioned 8mm float, thats wrong it's 7.5 mm

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another option if fuel is suspect or not known

use a 1:2 mix of Maxima 929 Castor and Maxima full synthetic. They claim it out HPs anything else on the dyno as well as being compatible with all brands of fuel. They can use any fuel and not have jetting issues related to oil/fuel compatibility.

The synthetic apparently stops the castor's gumming/dirty deposits issues and the caster stops the synthetic's over loading of the crankcase oil residuals and subsequent need to 'clean out' the motor

this is an issue with riders travelling and how they overcome different fuels from different regions and use this method at competition worldwide

Edited by coley13

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But why does it start with no choke ? a hotter plug is just hiding the poor jetting i thought ? what makes me wonder is how i can go from a 32.5 to a 27.5 and make no difference. thanks for another way to go about it tho. this carb just doesn't make sense. The guy i bought the bike from said he had fouling issues too his fix was a 32.5 pilot and 420 main. and ran amsoil domonator at 50:1 and it fixed it, so he said. the only thing i change before it started fouling plugs is the oil, which was golden spectro. its semi snythetic. never had any problems with that oil before.

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sea level

run an 8 plug

28/69 needle

do not lean the pilot less than 45 too big a transition from pilot to straight section will result in fouled plugs

2nd clip position summer, 3 rd winter

430 main, 440 winter

dont fall for 32:1 crap internet people feed you. A quality oil like motul 800 will easily go 50:1 in a 125. i started at 40:1 playing it safe and gone to 45:1 with that jetting but if i went to 50 those specs would require a change. But i will be doing that in the near future. The big gap 125 world record holder runs 50:1 all day in that bike with no problem with motul 800.

those settings sound rich dont they, never fouled a plug and i ride ST. Only gripe would be the tmx38 carb is sensitive to air screw adjustments, 1/4 usually settles that but it is a pain sometimes. But the bike makes great power. Aussie fuel is different 98 octane i'm running but i believe there is a difference between ron and mon, sort that yourself

edit, i believe someone mentioned 8mm float, thats wrong it's 7.5 mm

i suggested 32:1 in hopes he could bump up his pilot jet number, i didn't diss 50:1, although i personally wouldn't run it (friends have without problems).

My plug experiences

The first time i fouled a plug i replaced it with a br8es and when i went to put the stock # plug back in, the 8es' electrode was perfectly tan. Right now the br9eg is slightly on the rich side without fouling and i haven't had one come out tan. Not sure if this due to the "es" or the "8". I think we used to use br8es' in our kx65 and cr85s without problems (can't remember what stock was for those though). Also used spectro golden in them.

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