YZ125 bogging.

Michaelh1001
Edited Date/Time 9/2/2022 8:26am
I got a 17’ YZ125 and recently on the last 2 rides it seems that right when I start it and ride it the powervalve doesn’t want to open up and just keeps bogging, this happened after putting a lightly used spark plug in, so I gone ahead messed with the idle/air screw and put a new spark plug in and it fixed the issue and it ran great for around 1.5hr but randomly after shutting off the bike and starting it again it wouldn’t want to rev out anymore. So I was done for the day. Would anyone know if it’s in need of a simple carb clean or do I have to clean the power valve, top end was done 10 hours ago just forgot to clean the PV. Also it has a full FMF system and I’m not sure if the last owner had jetted it. It only leaks a little oil from the power valve breather but none from the silencer. Also I always used NGK BR9ES as I didn’t want to spend $15 on 1 spark plug
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Paul_Pitzonka
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Paul_Pitzonka 9/1/2022 10:10pm
9/1/2022 10:10pm
Yz125s are notorious for the pin in the power valve backing out and causing the valve not to open correctly...
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FGR01
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FGR01 9/2/2022 8:26am
9/2/2022 8:26am
Step-1, loosen and remove the sump plug on the bottom of the carb float bowl. Try to keep it upright and not dump the fuel out of it as you remove it. This will allow you to see if any dirt or crud is sitting in the bottom of the carb. Sounds like you might have some crap in there getting sucked up into the jets. If there's anything there, rotate the carb and remove the pilot and main and clean them well. If it's really cruddy, might need to remove the entire carb for a proper cleaning.
Michaelh1001 9/2/2022 9:23am
9/2/2022 9:23am
FGR01 wrote:
Step-1, loosen and remove the sump plug on the bottom of the carb float bowl. Try to keep it upright and not dump the fuel out...
Step-1, loosen and remove the sump plug on the bottom of the carb float bowl. Try to keep it upright and not dump the fuel out of it as you remove it. This will allow you to see if any dirt or crud is sitting in the bottom of the carb. Sounds like you might have some crap in there getting sucked up into the jets. If there's anything there, rotate the carb and remove the pilot and main and clean them well. If it's really cruddy, might need to remove the entire carb for a proper cleaning.
Ok I’ll take a look at that soon

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Jayce_276
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Jayce_276 9/5/2022 5:07pm
9/5/2022 5:07pm
Paul_Pitzonka wrote:
[img]https://p.vitalmx.com/photos/forums/2022/09/01/566660/s1200_C8664888_5DC3_4E7D_AACA_A088D8F4A109.jpg[/img]

I had this same problem on my power valve on my 2007 yz125. I ended up cutting a slightly larger drill bit and pressing it into the hole on the power valve arm.
doitinthewoods 9/12/2022 10:51am
9/12/2022 10:51am
I would think it’s more then likely the pin in the power valve but if it isn’t make sure your primary bolt it tight. I had that bolt losen up on my yz250 and it got pushed out the sidecase. That bolt holds the gear that runs the power valve

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