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07 cr125 keeps fouling plugs

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The bike is brand new and the dealer is no help at all, the head mechanic said he is not too good with 2 strokes , they called Honda and told us that they will change the pilot jet but this is a new bike ( not mine by the way ) has anyone else had this problem , suggestions ? mixture is 32-1, air filter clean,tried hotter plug but no good there either. You ride the crap out of it but it still is fouling a plug every hour or so riding time. the dealer is getting tired of us calling , so I ask the experts, help?

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Move the clip on the needle up one position, or go down on the mainjet 2 or 3 steps then try it out, and ditch the stock air filter they are NO GOOD.

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Move the clip on the needle up one position, or go down on the mainjet 2 or 3 steps then try it out, and ditch the stock air filter they are NO GOOD.

What is wrong with the stock air filter?

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did you buy it from la cyclesports by any chance?

i bought an '03 there and it ran like crap since day one. till this day i am trying to figure out the jetting. I'm going to order a different carb for the bike to fix the problem.

hope you get it figured out. the cr 125 jetting/carb BLOWS

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I know this bike, honda told the dealer to put a #40 slow jet in it.So far after today it has fouled 5 plugs.He is right about the dealer they screwed up on my pipe,and screwd up on this 125 purchase and to think i spent $11,000 and they have the nerv to blame the rider,and to call back after i stoped yelling after the 3rd pluged fouled.Still have not seen the#40 slow jet they said they orderd.To bad my CRF150R can keep up with this bike no problem.

Bike was bought at pacific motorsports.

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I know its the jetting sometimes I let my frustration get the best of me.Out of the last 9 bikes and one quad it's the only one I had problems with. Im sure it's something simple.I think I will let the dealer put the slow jet in,if it dosen"t work I think the needle clip sounds like the next step.

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The bike is brand new and the dealer is no help at all, the head mechanic said he is not too good with 2 strokes , they called Honda and told us that they will change the pilot jet but this is a new bike ( not mine by the way ) has anyone else had this problem , suggestions ? mixture is 32-1, air filter clean,tried hotter plug but no good there either. You ride the crap out of it but it still is fouling a plug every hour or so riding time. the dealer is getting tired of us calling , so I ask the experts, help?

check your air screw that it's not all the way in, if it is as soon as you let off the throttle it will try to foul, a hotter plug is not a fix.

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Jetting is something a 2 stroke rider should know how to do. Many things affect jetting and you cannot take it to the dealer every time your bike pings, flutters, or the plug loads up. Do yourself a favor buy some jets and learn how to tune your bike yourself. Its not that hard, it does not take long, and you save $. The dealer could jet the bike fine at the dealership, yet you could travel 2 miles and your bike runs like crap, why? Altitude, air pressure, air temperature, humidity, and which way the wind blows. Don't give the dealer free $, and set yourself up for the run-around. At most for the first time it may take an hour.

Read it, learn it, love it, jetting.

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jetting is easier said than done on the cr 125. The engineer who designed the carb setup is a chimp!

Any slight raise in temp or humidity and your jetting goes to h$ll.

Live in southern cali? Want to give it a try? you can jet mine.

I leaned out all of the jets several stages and it still fouls plugs and dies after 30-40 minutes of riding. I finally said &%$# it and run 44:1 now and it runs fine. Plug is nice and tan. There's still spooge all over the muffler, but i can live with that. 32:1 never worked for me, even with leaning out the main and pilot jet along with lowering the needle clip.

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I have the same problem even with a 390 main thats 4 steps from stock and we leaned the air screw too 21/2 out and it needs more work....

please help...

Originally Posted by nac-nacer

Move the clip on the needle up one position, or go down on the mainjet 2 or 3 steps then try it out, and ditch the stock air filter they are NO GOOD.

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1- Dirtbikes come rich from factory.

2- Don't change the plug heat (unless you know what you're doing)

3- Lowering the needle clip richens the mixture

4- If it's fouling at 1/2 throttle and up, changing the PJ won't resolve

5- I would never use 44:1 on a 125

6- Mikuni carbs on newer CR's are finicky

7- Do a search on Jetting

8- Check to see if the air screw is not all the way in as mentioned above

9- Set it to 2 turns out

10-Go one or two sizes down on the stock MJ

11-Needle clip on middle

12-New plug

13-Ride, see if it bogs or sputters (off idle; from 1/8 throtle to 3/4; from 1/2 throtle to WOT) - To see what's going on with each circuit.

I never used it, but many TT's say that the needles from the JD kit do wonders for these carbs. Good Luck

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The bike is brand new and the dealer is no help at all, the head mechanic said he is not too good with 2 strokes , they called Honda and told us that they will change the pilot jet but this is a new bike ( not mine by the way ) has anyone else had this problem , suggestions ? mixture is 32-1, air filter clean,tried hotter plug but no good there either. You ride the crap out of it but it still is fouling a plug every hour or so riding time. the dealer is getting tired of us calling , so I ask the experts, help?

We purchased a new CR125R back in late February of this year and went through the exact same thing with fouling plugs left and right. All we did was jet the bike down and the problem has been solved. The only change that we did was swap out the stock 400 main for a 380, left the pilot jet and clip as they were out of the crate. Bear in mind that this bike was a leftover 2002 CR125R. I can't tell you why the dealership still had an '02, '03, and '04 model all three in their inventory this year, but they did. I bought the '02 for my stepson because I got an extremely good deal on it.

At any rate, the bike runs great now! No more fouling, excessive smoking, sputtering, spooge, etc. In the case of our CR125R it was indeed all about jetting. By the way, we're running this bike at 32:1 with 93 octane gasoline and Suzuki CCI-Super 2 Two-Cycle Engine Oil. A close friend sold his 2001 RM125 and he had a lot of Suzuki oil leftover that he gave us.

Good luck with your bike. You'll get it right eventually and then it will be a blast to ride.

Ron M.

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as someone said, stock air filters are junk. got rid of that pos and things got better. as for the jetting issue, we changed the pilot and the position and now it runs good but still not perfect. i will keep looking into the search and will find it sooner or later,

thanks guys

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as someone said, stock air filters are junk. got rid of that pos and things got better. as for the jetting issue, we changed the pilot and the position and now it runs good but still not perfect. i will keep looking into the search and will find it sooner or later,

thanks guys

Which type of aftermarket air filter did you end up going with?

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