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AndyB1350

Cr125 wont start but will run when primed

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Hey everyone,

Couldnt get my '97 2 smoke to kick over, and long story short took the carb apart and gave a quick clean on the trail and blew through the pilot and main jets, pilot seemed to be gunked up but came clear. Put back together and still doesnt kick over. If I prime it by pouring some gas on my air filter then she fires right up and then will run like a dream and I can ride it around. But once it dies I cant start it without priming it again. My guess is the pilot jet circuit but it seems to idle fine once it starts. So just trying to see if anyone has a better idea (I'm out working in Minnesota for 2 weeks, so I haven't been able to try anything on it until I get home next time).

 

Thanks in advance guys n gals!

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Posted (edited)

First check as stated above if the petcock is flowing gas. Disconnect the gas line to the carb. and see if you have gas flowing good...

Then Check the float valve inside the carb,  Its what let's fuel into the carb wen carb  needs gas. it's connected just below the floats and rides In the needle valve seat which is copper.

Probable a little dirty and stuck. U can try lightly tapping the side of the float bowl while carb is still on the bike, and see if u get it to unstick.

But the best way is to pull the carb and give it a thorough cleaning and inspection

Edited by Orange Crush 500
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You poured gas directly on the air filter?????? BIG nono man! All the dirt that the filter trapped is most likely in the carb and the motor. Remove the air filter and throw it away. Clean out the air box real good with the carb removed and a rag gently stuffed into the reed block. Take the carb apart and clean it on the bench. Spray all the jets and passages out with carb cleaner and compressed air. Make sure the float level is correct and the needle clip in center slot. What size jets are you running? If the plug is black and wet the pilot is too big. If it's white and dry the pilot is too small. What pipe are you running on the bike? Taking a carb apart on the trail is an invitation for dirt and dust to enter the reed cage and run through the motor ruining the ring(s) sealing surface with the cylinder and possibly scoring the cylinder walls. 

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FPMXer.... We've used gas in the air cleaner to start bikes many times. It works great. We've reused air cleaners many many many times. This guy is right on track on how to get his bike started. When you shoot some gas right into the carburetor, if the engine starts you know you have a carburetor problem.

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97 is pretty old.  Possibly low compression? Low enough to not have enough draw,pull of fuel?

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3 hours ago, arthur6 said:

FPMXer.... We've used gas in the air cleaner to start bikes many times. It works great. We've reused air cleaners many many many times. This guy is right on track on how to get his bike started. When you shoot some gas right into the carburetor, if the engine starts you know you have a carburetor problem.

Well I would think the gas would clean part of the dirty filter into the carb. I have cleaned them with gas but off the bike and saw all that sand and dirt fall out of the filter. If you need to induce starting fluid or gas I always put it down the plug hole. If it starts and runs then you know the issue is the carb.

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5 hours ago, yz250f 78 said:

97 is pretty old.  Possibly low compression? Low enough to not have enough draw,pull of fuel?

That's the thought that crossed my mind too, it runs fine once running, so the carb/fuel flow should be ok. Other thing may be a weak spark when kicking it, the extra fuel ignites easier.

I'd still pull the carb again and give 'er a good clean, it's free to do and you never know....

Edited by DEATH_INC.

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