2 stroke all of a sudden cutting out and seems to be running rich off the bottom.

debun
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debun
I was riding my 01 RM125, went into slow speed corner and the bike started to struggle then dies. I was able to get the bike to start, but it wouldn't idle at all, and sounded like crap then would die.
I tried adjusting the air screw and idle no luck. Cleaned the carb, spark plug, set the float height, checked the reeds and made sure the power valves moved with the linkage. The bike fires up but lots of smoke. Cleaned it out, adjusted my idle and air screw and said great ready to ride. This Sunday I get to the track, bike will not start. 45 minutes of dicking around it finally fires up and seems to be super rich of the bottom. Ran like crap until I cleaned it out (WFO everywhere) and seems to run fine once 1/2 throttle or more. I rode the entire day but each time I wasn't on the pipe it sounds like crap. Any clue what might be going on?
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tsmitty2661
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tsmitty2661 10/18/2021 3:04pm
10/18/2021 3:04pm
I would drop your pilot. Up to half a throttle youre into needle clip territory so you could also drop your needle one clip. Start with your pilot and go from there
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willbilly
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willbilly 10/18/2021 5:35pm
10/18/2021 5:35pm
If the smoke smells like gear oil your right crank seal has failed. Don’t need to split cases to replace.
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debun
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debun 10/20/2021 6:18am
10/20/2021 6:18am
willbilly wrote:
If the smoke smells like gear oil your right crank seal has failed. Don’t need to split cases to replace.
Thanks, best lead I got but I have a bad sense of smell hahah. I ordered the seal hopefully it gets here before the weekend.
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JMCR250
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JMCR250 10/20/2021 4:08pm
10/20/2021 4:08pm
Second the crank seal point, but also take a good luck inside the carb and make sure nothing has broken or come loose. I've heard of people whose two-stroke suddenly started running poorly only find a jet had backed out, a slide had broken or developed a crack or something like that. Good luck.
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debun
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debun 10/27/2021 7:21am
10/27/2021 7:21am
I checked the crank seals, they all look good. I'm now wondering if it's electrical. Cleaned the carb and that all looked good too.
Layton
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Layton 10/27/2021 10:43am
10/27/2021 10:43am
debun wrote:
I checked the crank seals, they all look good. I'm now wondering if it's electrical. Cleaned the carb and that all looked good too.
You can’t tell if a crank seal is bad by looking at it. Especially on the clutch side.

Just replace it.
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debun
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debun 10/29/2021 5:01am
10/29/2021 5:01am
debun wrote:
I checked the crank seals, they all look good. I'm now wondering if it's electrical. Cleaned the carb and that all looked good too.
Layton wrote:
You can’t tell if a crank seal is bad by looking at it. Especially on the clutch side.

Just replace it.
I put 5psi of air in the motor and sprayed for leaks.
Paw Paw 271
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Paw Paw 271 10/29/2021 10:32am
10/29/2021 10:32am
Do a compression and leak test to find the issue.
Low compression will first show up as a rice condition due to incomplete burning of the fuel charge.

Paw Paw
mwssquad827
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mwssquad827 11/4/2021 9:15pm
11/4/2021 9:15pm
Interesting info.. my Kdx is doing a similar rich bog .. 1/2–full throttle
debun
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debun 11/5/2021 6:30am
11/5/2021 6:30am
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired it up on the stand and seems to be much better but I didn't get to ride it yet. It may have been an electrical issue and just had a weak spark.
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Arln.rm125
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Arln.rm125 11/6/2021 9:02pm
11/6/2021 9:02pm
debun wrote:
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired...
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired it up on the stand and seems to be much better but I didn't get to ride it yet. It may have been an electrical issue and just had a weak spark.
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the plug cap along with a really loose wire. Now have a ft of wire in my bag and 10 some foot of wire in my box. Its super cheap stuff so might as well have it. Update once you ride it
debun
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debun 11/9/2021 5:55am
11/9/2021 5:55am
debun wrote:
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired...
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired it up on the stand and seems to be much better but I didn't get to ride it yet. It may have been an electrical issue and just had a weak spark.
Arln.rm125 wrote:
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the...
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the plug cap along with a really loose wire. Now have a ft of wire in my bag and 10 some foot of wire in my box. Its super cheap stuff so might as well have it. Update once you ride it
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap. There was definitely corrosion on the cap so that might have been the only issue. I went with a replacement NGK waterproof cap which was less than $5 bucks so well worth the money if you pressure wash your bike.
Arln.rm125
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Arln.rm125 11/9/2021 6:30am
11/9/2021 6:30am
debun wrote:
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired...
I did a top end. Same compression values as before and still ran like crap. I replaced the stator and spark plug wire and cap. Fired it up on the stand and seems to be much better but I didn't get to ride it yet. It may have been an electrical issue and just had a weak spark.
Arln.rm125 wrote:
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the...
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the plug cap along with a really loose wire. Now have a ft of wire in my bag and 10 some foot of wire in my box. Its super cheap stuff so might as well have it. Update once you ride it
debun wrote:
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap...
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap. There was definitely corrosion on the cap so that might have been the only issue. I went with a replacement NGK waterproof cap which was less than $5 bucks so well worth the money if you pressure wash your bike.
Glad to hear it’s fixed. Shit for that price I may toss a new cap on my bike while it’s all apart. Thanks for the info on that. Did you find it locally and just compare caps to see what you needed or did you order it online?
debun
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debun 11/9/2021 1:00pm
11/9/2021 1:00pm
Arln.rm125 wrote:
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the...
Spark plug wires on the rm's seem to have issues. My 07' dealt with the same issues and it ended up being some corrosion on the plug cap along with a really loose wire. Now have a ft of wire in my bag and 10 some foot of wire in my box. Its super cheap stuff so might as well have it. Update once you ride it
debun wrote:
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap...
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap. There was definitely corrosion on the cap so that might have been the only issue. I went with a replacement NGK waterproof cap which was less than $5 bucks so well worth the money if you pressure wash your bike.
Arln.rm125 wrote:
Glad to hear it’s fixed. Shit for that price I may toss a new cap on my bike while it’s all apart. Thanks for the info...
Glad to hear it’s fixed. Shit for that price I may toss a new cap on my bike while it’s all apart. Thanks for the info on that. Did you find it locally and just compare caps to see what you needed or did you order it online?
I ordered if from Amazon but you could probably get it locally. This is what I ordered NGK LB05EP Resistor Spark Plug Cap this is a cheat sheet on the options https://www.ngksparkplugs.co.za/products/ngk-resistor-caps/
Arln.rm125
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Arln.rm125 11/9/2021 8:42pm
11/9/2021 8:42pm
debun wrote:
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap...
I rode this weekend and the issues seemed to be fixed. It was one of the components I replaced, so stator, spark plug wire or cap. There was definitely corrosion on the cap so that might have been the only issue. I went with a replacement NGK waterproof cap which was less than $5 bucks so well worth the money if you pressure wash your bike.
Arln.rm125 wrote:
Glad to hear it’s fixed. Shit for that price I may toss a new cap on my bike while it’s all apart. Thanks for the info...
Glad to hear it’s fixed. Shit for that price I may toss a new cap on my bike while it’s all apart. Thanks for the info on that. Did you find it locally and just compare caps to see what you needed or did you order it online?
debun wrote:
I ordered if from Amazon but you could probably get it locally. This is what I ordered [url=https://www.amazon.com/gp/product/B001KOL5SG/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1]NGK LB05EP Resistor Spark Plug Cap[/url] this is a...
I ordered if from Amazon but you could probably get it locally. This is what I ordered NGK LB05EP Resistor Spark Plug Cap this is a cheat sheet on the options https://www.ngksparkplugs.co.za/products/ngk-resistor-caps/
Thanks for the info man. Definitely will be picking a few of those up just to have. Cheers
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