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View Full Version : Yt 125 issues


Jal_pom2122
06-16-2019, 02:08 PM
I got a 82 yt 125, has commpression but wont fire. Have cleaned carb, new spark plug, oil, fuel. Wondering if anyone has any ideas for me to try
RubberSalt
06-17-2019, 12:18 PM
Sounds like you have bad reeds, plugged pilot jet circuit, spun flywheel, or may have an air leak. Any air leak will lean the motor out and make it hard to start. And if you get it running, may burn up the piston.

Pull the plug and confirm you have spark. If you have spark, make sure the flywheel hasn't spun.

Being you've already cleaned the carb, pull the reeds and inspect them. They need to be shut(super tiny gap is fine). Perform a leak down test. You can do a search for 2 stroke leak down test. This method of testing came out after the manuals were written, so it wont be in there. All your doing is pressurizing the entire crank case/cylinder to about 7 psi and looking for air leaks.
Terry Preston
06-17-2019, 09:32 PM
Sounds like you have bad reeds, plugged pilot jet circuit, spun flywheel, or may have an air leak. Any air leak will lean the motor out and make it hard to start. And if you get it running, may burn up the piston.

Pull the plug and confirm you have spark. If you have spark, make sure the flywheel hasn't spun.

Being you've already cleaned the carb, pull the reeds and inspect them. They need to be shut(super tiny gap is fine). Perform a leak down test. You can do a search for 2 stroke leak down test. This method of testing came out after the manuals were written, so it wont be in there. All your doing is pressurizing the entire crank case/cylinder to about 7 psi and looking for air leaks.

What colour is the spark crisp, bright blue..?
ps2fixer
06-17-2019, 11:11 PM
FYI, the color of the spark isn't a perfect test, white/blue can still be bad, it's just when the spark is orange/red/yellow you know 100% it's weak spark. Proper test is with a spark gap tester, standard is normally 6mm gap, but I've seen a service manual mention 7mm not long ago.

Here's an example of a machine with great spark, but won't fire, coil was the fault.

https://www.youtube.com/watch?v=dipmevU5cjU

Anyway, good luck with the machine, being 2 stroke there's a fair chance someone could have damaged the piston/cylinder/rings if they didn't run it with mixed gas, or ran it too lean, at least it happens more than it should in the chainsaw world.