03 KX125 start-up issues

zachjk · 02-16-2007

I just picked up an 03 kx125. I'm having an extremely hard time starting it when its cold. It takes way longer than is normal. Once i do get it started, I have to keep the throttle up, or it will bog out between shifts. What can I do to fix this. The previous owner told me it has about 13 hours on a fresh rebuild. Any help will be greatly appreciated.
Zach

FPMXer · 02-17-2007

First off is the choke on when starting it cold? Just a few other things that could be wrong is a dirty carb, air filter, bad reeds or even bad fuel. I would start with checking the plug and it's condition and do a compression test. There should be about 125-145 psi on the cylinder. If it has about 13 hours on a new top end it should be closer to 145+ psi. If those are good then check the condition of the air filter, but I would install a new or cleanly oiled filter. If the filter is dirty then while the filter is out I would remove the carb and clean it out and check the condition of the reeds. Yes this is alot of stuff to do but I do it all the time to make sure my bike is running in tip top shape.

zachjk · 02-17-2007

Choke is on when starting it cold. I'll clean out the carb tomorrow before i ride. I just put on a new air filter that i got with the bike. The old one was terrible. I'll check compression as soon as I pick up a compression tester. Plug is new though. I appreciate it. It started a little quicker today though so that was nice.

02-16-2007	#1 (permalink)
zachjk Newbie Join Date: Feb 2007 Location: VA Posts: 12	03 KX125 start-up issues I just picked up an 03 kx125. I'm having an extremely hard time starting it when its cold. It takes way longer than is normal. Once i do get it started, I have to keep the throttle up, or it will bog out between shifts. What can I do to fix this. The previous owner told me it has about 13 hours on a fresh rebuild. Any help will be greatly appreciated. Zach

02-17-2007	#2 (permalink)
FPMXer 2Stroke 4 life!! BTK Expert Join Date: May 2006 Location: Temecula, California Posts: 561	First off is the choke on when starting it cold? Just a few other things that could be wrong is a dirty carb, air filter, bad reeds or even bad fuel. I would start with checking the plug and it's condition and do a compression test. There should be about 125-145 psi on the cylinder. If it has about 13 hours on a new top end it should be closer to 145+ psi. If those are good then check the condition of the air filter, but I would install a new or cleanly oiled filter. If the filter is dirty then while the filter is out I would remove the carb and clean it out and check the condition of the reeds. Yes this is alot of stuff to do but I do it all the time to make sure my bike is running in tip top shape. __________________ 86' 250R Trike 88' LT500RJ Quadzilla My blood is yellow and red!

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02-17-2007	#3 (permalink)
zachjk Newbie Join Date: Feb 2007 Location: VA Posts: 12	Choke is on when starting it cold. I'll clean out the carb tomorrow before i ride. I just put on a new air filter that i got with the bike. The old one was terrible. I'll check compression as soon as I pick up a compression tester. Plug is new though. I appreciate it. It started a little quicker today though so that was nice.

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