2006 CR125 fouling plugs constantly

gavinmgrant
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gavinmgrant
Edited Date/Time 12/10/2018 10:27am
Hi guys,

I have a 2006 CR125 that is constantly fouling plugs. I'm using the BR8 (the hotter plug.) I live in North Carolina so we are at sea level. I moved from New Mexico ay 6,000 and she ran like a champ. Never had a problem with fouling plugs. I did a top end rebuild before I moved; piston, cylinder, and cylinder head and she ran great. Then I moved to sea level and always fouls plugs. I'm using a 410 main, 37.5 pilot (I did change the jets when I moved and the main and pilot are BRAND NEW genuine Honda parts so they're not clogged), and the second need clip position 32:1 ratio with amsoil dominator oil and 93 non-ethanol. I can ride it for about 20 minutes and it pulls hard and feels amazing. Then 5 minutes of putting around she shuts off. Every time the plug is wet and black. I started getting some oil shooting out the exhaust so I changed the right crank seal, stopped the oil problem. BUT it still is having the same plug fouling issue. My next plan of action was to do a resistance test of the stator. If you guys have any other ideas or checks please feel free to comment. I've also cleaned the carb and replaced the reeds with boyessen reeds. Not sure what else to do before looking into the electrical system. Thanks!
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kb228
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kb228 12/5/2018 4:43pm
12/5/2018 4:43pm
The 5 mins of putting around is likely the issue. 2 strokes are wide open or off. Try leaning out your pilot circuit and maybe look into the needle.
speed_racer
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speed_racer 12/5/2018 5:11pm
12/5/2018 5:11pm
maybe replace the oring on the seat, number three on the picture
carb

if it barely leaks the extra fuel heads towards the cylinder instead of out the overflow and it will be slightly rich
JWACK
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JWACK 12/5/2018 5:26pm
12/5/2018 5:26pm
Hey Gavin this is Wackerbarth from Albuquerque. Glad your still riding man!
Those jet sizes should be close to what you need. Do a plug test right after your 20 minute Moto and see if your burning a lite chocolate color. Also check your float height. What needle are you using? See if you can find the number on it.
gavinmgrant
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gavinmgrant 12/5/2018 5:57pm
12/5/2018 5:57pm
speed_racer wrote:
maybe replace the oring on the seat, number three on the picture [url=http://shop.missionmotorsports.com/fiche_section_detail.asp?section=3045484&category=Motorcycles&make=Honda&year=2006&fveh=12674]carb[/url] if it barely leaks the extra fuel heads towards the cylinder instead of...
maybe replace the oring on the seat, number three on the picture
carb

if it barely leaks the extra fuel heads towards the cylinder instead of out the overflow and it will be slightly rich
Cool thanks I'll give that a shot.

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gavinmgrant
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gavinmgrant 12/5/2018 6:01pm
12/5/2018 6:01pm
JWACK wrote:
Hey Gavin this is Wackerbarth from Albuquerque. Glad your still riding man! Those jet sizes should be close to what you need. Do a plug test...
Hey Gavin this is Wackerbarth from Albuquerque. Glad your still riding man!
Those jet sizes should be close to what you need. Do a plug test right after your 20 minute Moto and see if your burning a lite chocolate color. Also check your float height. What needle are you using? See if you can find the number on it.
Hi John, long time no see! Little blast from the past lol.
I've been checking the plug every time it foulds and is straight black and wet. i'll find the picture and post it.
I'm not sure on the needle, I havent changed it, only the position. I'm in the middle east right now so i wont be able to check the needle until next month Sad
gavinmgrant
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gavinmgrant 12/5/2018 6:13pm
12/5/2018 6:13pm
JWACK wrote:
Hey Gavin this is Wackerbarth from Albuquerque. Glad your still riding man! Those jet sizes should be close to what you need. Do a plug test...
Hey Gavin this is Wackerbarth from Albuquerque. Glad your still riding man!
Those jet sizes should be close to what you need. Do a plug test right after your 20 minute Moto and see if your burning a lite chocolate color. Also check your float height. What needle are you using? See if you can find the number on it.



JWACK
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JWACK 12/5/2018 6:13pm
12/5/2018 6:13pm
Thank you for your service young man!. I'm glad your doing well. Yes as soon as your back check the needle/seat condition and type also the float height. I really don't think you have an electrical problem. But I've been wrong once before so anything can happen!
gavinmgrant
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gavinmgrant 12/5/2018 6:21pm
12/5/2018 6:21pm
JWACK wrote:
Thank you for your service young man!. I'm glad your doing well. Yes as soon as your back check the needle/seat condition and type also the...
Thank you for your service young man!. I'm glad your doing well. Yes as soon as your back check the needle/seat condition and type also the float height. I really don't think you have an electrical problem. But I've been wrong once before so anything can happen!
Thank you, I appreciate it. The needle and seat looked to be in good condition. I wonder about the float as well. Might be letting too much fuel in. I'm making a list of trouble shooting ideas to check when I get back. Any recommendation for what the float should be set at?
b_kowalsk
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b_kowalsk 12/7/2018 8:07pm
12/7/2018 8:07pm
Just my 2 cents. I have an 07 CR125 and also knew somebody that bought one brand new and remember him having an issue fouling plugs since day 1. My 07 seems much more prone to fouling plugs than my old yz125 or any other bike I have owned for that matter. For what it's worth they don't seem to like being ridden at lower RPM and just seem really finicky bikes to set up for different conditions.
Honda Man 66 12/8/2018 8:44am
12/8/2018 8:44am
My Guess would be it needs a new carb. I had similar issues with 2 CR250’s. I put an air striker on one and a Lectron on the other. They both run perfectly now.
JMCR250
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JMCR250 12/8/2018 12:51pm
12/8/2018 12:51pm
My son's 07 was the same way. The bike came from Honda jetted way rich. The previous owner wasn't too proficient and made it worse. We got a JD kit with the bike, and after installing that it was much better. After a few further small adjustments, it runs clean and strong (ours has a PC pipe and silencer). My 250 started running poorly and I attribute it to crappy ethanol gas sitting in the carb over the winter and a blown out silencer packing. Cleaned the carb, replaced the packing and it runs like brand new. I'd go ahead and replace the float jet, as someone mentioned. Ethanol eats the rubber o-ring at the base of the jet.
r18b
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r18b 12/9/2018 6:19am
12/9/2018 6:19am
" I moved from New Mexico ay 6,000 and she ran like a champ. Never had a problem with fouling plugs. I did a top end rebuild before I moved; piston, cylinder, and cylinder head and she ran great."


Simpel, go lower on the main.if the main is right then you can play with the rest. There is moreee then enuff oil on the spark thats for sure. So mixing to much oil or you ride it not hard enuff. Or try 40:1 or try a different oil

A 85 and a 125 will foul plugs right away if the jetting is to rich and you don't burn it but cruising with the bike.
JMCR250
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JMCR250 12/9/2018 10:22am
12/9/2018 10:22am
The main is definitely too rich stock. I don't remember the stock jetting specs but it sounds like your present set up is close to them.

One of the issues with the stock jetting is the taper of the needle. The JD kit supplies two replacement needles and overall jetting specs (and jets) covering a range of conditions/altitudes. The kit absolutely cleaned up my son's bike. It was so rich when we bought it that the original owner had installed a super hot lawn mower plug to get it to run. (Glad we discovered that right away).

Good luck.
gavinmgrant
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gavinmgrant 12/9/2018 7:39pm
12/9/2018 7:39pm
JMCR250 wrote:
The main is definitely too rich stock. I don't remember the stock jetting specs but it sounds like your present set up is close to them...
The main is definitely too rich stock. I don't remember the stock jetting specs but it sounds like your present set up is close to them.

One of the issues with the stock jetting is the taper of the needle. The JD kit supplies two replacement needles and overall jetting specs (and jets) covering a range of conditions/altitudes. The kit absolutely cleaned up my son's bike. It was so rich when we bought it that the original owner had installed a super hot lawn mower plug to get it to run. (Glad we discovered that right away).

Good luck.
The stock main jet is a 430 (which is insanely rich), 55 pilot, and the third clip position. Do you think I should try going leaner on the main and pilot as well? Maybe a 400 or a 390 for the main? And maybe a 32.5 on the pilot? The JD kit seems to show it supplies both of those sizes which is nice. I'll have to look at the needle number when I'm available to do so as well.
Matt Fisher
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Matt Fisher 12/10/2018 9:34am
12/10/2018 9:34am
Pro Circuit suggests 410 with a 50 pilot, stock needle in position 2.
https://www.procircuit.com/jettingspecs2.htm#2006

MXA suggests 440, a 27-67 needle in position 3 and a 50 pilot.
https://motocrossactionmag.com/2006-honda-cr125-test/

Stock is a 430 with a 55 pilot. Honda's jetting from the factory may be rich, but not that rich.

If you're running a 37.5 pilot and fouling plugs, there's a mechanical issue. Start with the right side crank seal.
gavinmgrant
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gavinmgrant 12/10/2018 10:27am
12/10/2018 10:27am
Matt Fisher wrote:
Pro Circuit suggests 410 with a 50 pilot, stock needle in position 2. https://www.procircuit.com/jettingspecs2.htm#2006 MXA suggests 440, a 27-67 needle in position 3 and a 50...
Pro Circuit suggests 410 with a 50 pilot, stock needle in position 2.
https://www.procircuit.com/jettingspecs2.htm#2006

MXA suggests 440, a 27-67 needle in position 3 and a 50 pilot.
https://motocrossactionmag.com/2006-honda-cr125-test/

Stock is a 430 with a 55 pilot. Honda's jetting from the factory may be rich, but not that rich.

If you're running a 37.5 pilot and fouling plugs, there's a mechanical issue. Start with the right side crank seal.
Right side crank seal has already been changed. Float level is my next check.

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