# Homelite 2 Cycle UT20769 Not starting.



## fbennett (Jul 21, 2013)

Hello,

I have changed the Carburetor, Starting Coil, fuel lines and fuel filter, checked for carbon build up, removed the muffler and spark arrestor, only thing I have left is to change the piston ring. The piston does not look scored. I have performed a spark test and get a blue spark. I also used staring fluid and it still does not even attempt to start. 

Any ideas?

Thank you.


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## usmcgrunt (Sep 16, 2007)

Hello and welcome to Hobby Talk.Have you done a compression test? If the reading is less than 90 to 100 psi,the cylinder and\or piston is scored and the unit will be difficult to impossible to start.If the trimmer head was ever stuck in heavy grass or weeds,the flywheel key may have sheared and the timing is off.A sheared key will still show spark,just at the wrong time on the compression stroke.Let us know what you find and someone here will be glad to help you.


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## fbennett (Jul 21, 2013)

Thank you usmcgrunt,

I have not performed the compression test yet. 

The flywheel looked ok and how would I know if it was sheared?

Thank you.


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## usmcgrunt (Sep 16, 2007)

You would have to remove it and check to make sure that the key,which is cast as part of the flywheel,is still in tact.There will be a notch in the crankshaft that the flywheel key fits into.Larger flywheels use a separate key which is replaceable if sheared.


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## fbennett (Jul 21, 2013)

Thanks usmcgrunt,

Oh, on the other side of the flywheel at the crankshaft, not where the drive connector is, the back of the flywheel correct?

I want to make sure where talking the same thing, flywheel and Rotor are the same correct?

Thank you.


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## usmcgrunt (Sep 16, 2007)

Yes flywheel and rotor are the same.It is around 3 1/2 inches in diameter with fins on it.The ignition coil sits on top of it and the key will be on the inside of the flywheel.


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## fbennett (Jul 21, 2013)

Hi usmcgrunt,

I am able to turn the flywheel and it moves the piston, I don't think the flywheel is slipping. Would I need to remove the bolt to see the key?

Thank you.


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## usmcgrunt (Sep 16, 2007)

Even if the flywheel key is sheared,it will still be tight enough on the crank shaft to move the piston up and down. Think of the flywheel as a clock face.If the flywheel key is at the 12 o'clock position,and the crankshaft slot is at the 2 o'clock position,the timing will fire before or after the piston is at top dead center and cause a no start\hard start condition. A sheared flywheel key is rare,but still a possibility.You really need to do a "compression test" before you take anything else apart.


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## fbennett (Jul 21, 2013)

Thank you usmcgrunt,

Would I be able to see the key with out removing the bolt from the flywheel?

Thank you.


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## usmcgrunt (Sep 16, 2007)

Here is a video showing the removal and replacement of a flywheel on a different model trimmer.The procedure on yours would be very similar.As I said earlier,it is possible for the key to shear,but fairly rare.You really should do the compression test before undertaking the possibly unneeded flywheel removal.All engines need fuel,compression and spark at the correct time to run.You have to confirm you have each during the diagnostic phase of testing.You have spark?,you have fuel?now you need to prove compression is good.


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## Spit (Nov 3, 2006)

The cylinder on some of these units can come loose from the crankcase...be sure that the 2 bolts that hold these parts together are good & tight. You can even have good compression with this problem and still it will not start because it is not getting fuel mix into the cylinder 

Spit


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