Yz 125 problem

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10/1/2018 7:35 PM

I have a 2017 YZ125 with v force reeds and FMF pipe. It’s never given me any trouble jetting is on point idle is too. I was sitting at the gate at one of my races and when it came time to start my bike it wouldn’t. So I pushed it back to the pits and finally got it running but it bogged until it was warm. I put a new plug in. I cleaned the power valve and my piston had 9 hours and still looks good. Think maybe carb?

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10/1/2018 7:54 PM

Shitty gas or clogged air filter. Check the easy stuff first

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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/1/2018 7:57 PM

Marty1028 wrote:

Shitty gas or clogged air filter. Check the easy stuff first

I change out air filter every ride and gas is premium mixed with VP race gas

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10/2/2018 6:27 AM

Take your carb off. Remove the float bowl. Check the needle jet to make sure it doesnt have a speck of dirt on it preventing it from seating flush. (sometimes when this happens you just dump fuel out of the bowl while standing still) Also make sure the needle jet isnt grooved. After that check the float tabs arent bent or damaged. Then remove the pilot and main jets, clean them (id just replace with new), then clean all the circuits out of the carb. Reassemble.

Next while you have the carb apart and off the bike, check your vforce reeds and the cage. Did you double gasket and yamabond the gaskets? Vforce reed cages are notorious for not sealing correctly and causing lean conditions. You'll know because the plug reading will be very light almost white. Make sure the reeds are sealing and aren't chipped.

Last, put fresh gas in it. Have you removed your petcock and cleaned the little skinny filter thing at all? Those get gummed up sometimes.

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10/2/2018 7:55 AM

2stroked wrote:

Take your carb off. Remove the float bowl. Check the needle jet to make sure it doesnt have a speck of dirt on it preventing ...more

Easier way to check the petcock deal is just pull off the line and turn it on.
Hard starting is usually worn reeds or low compression(once you've checked all the easy stuff like spark and gas.

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My post is my opinion. If you don't agree with it, I'm OK with it.

10/2/2018 8:31 AM

9 hours on a top end is probably past due according to the service manual. Not sure if you are super aggressive but I'd get that top end changed.

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10/2/2018 2:17 PM

2stroked wrote:

Take your carb off. Remove the float bowl. Check the needle jet to make sure it doesnt have a speck of dirt on it preventing ...more

Moto96 wrote:

Easier way to check the petcock deal is just pull off the line and turn it on.
Hard starting is usually worn reeds or low ...more

Absolutely true. However what you can't determine without removing the petcock is how much lint, grit, sand, is adhered to the filter its self. Ive found that sometimes there are specks of grit in there that bounce around while riding and slow down the fuel flow. Once you stop riding on the tank settles, the speck can dislodge, fall, or become unattached. A small chance yes, but it only costs you a gasket and 5 minutes of time to check.

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