Problems with older Echo 660 EVL

[trailrunner]

Hello, long time viewer first time poster

Anyway my father has a 660 EVL that he loaned out and they had put a really high mixture of oil and gas into his saw and now it will no longer run. You can get it to hit but it will not stay running and it eventually floods out. I checked the compression and with one pull it only has about 100 psi but if you continue to pull on it the compression will top out at around 150 psi. It also backfires threw the carb. Im thinking either the carb is gummed up from the excess oil and or the flywheel key sheared. Im not familiar with this saw and i dont have a service manual so i figured i would come on here and ask you all for your advise. Thanks

 

[Brushwacker]

First thing I would do is pull the muffler and examine the piston, cylinder and rings through the exhaust ports for scouring,breaks and wear.
Has it been run with a good air cleaner only? If dirt has been getting in the engine it would wear things out prematurely, thus less compression and when you pull on it the fuel oil mix would coat the cylinder wall and the compression likely could go up. A ridge at the top of the piston stroke on the cylinder wall is a good indication of sucking dirt.
Carbon can build up and then break of and cause piston and ring damage also.
It could have had been accidently had the wrong fuel w/o mix in it and done some damage.
Take a look .











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[trailrunner]

Kewl thanks i will check it, The only other thing is that the muffler bolts had gotten loose.

 

[Stumpcutter1]

carb bolts tight?sounds like it could be sucking air

 

[Stumpcutter1]

did you change the plug it might help?

 

[trailrunner]

OK i just removed the muffler which did not have a gasket and the gasket surface is messed up from when the muffler was loose, the cylinder wayy has a bunch of small scratchs but non on the piston that i could see threw the exhaust opening. Only thing i noticed when i pulled the starter cord is that air was excaping by the piston into the exhaust.

 

[trailrunner]

I just installed a new spark plug and it is wet after i remove it after trying to start it. Ive checked the spark and it is good.

 

[Stumpcutter1]

Id leave the plug out for a day or so and give her a try again might have so much mix in it can't get it out,let it evaporate for a while might work Ive seen it happen before

 

[trailrunner]

I will try that, ive got the exhaust out too and unbolted the carb, i will check the gasket before i reassemble. Will missing the exhaust gasket hurt anything?

 

[Brushwacker]

I will try that, ive got the exhaust out too and unbolted the carb, i will check the gasket before i reassemble. Will missing the exhaust gasket hurt anything?

I donot know for sure, but if enough exhaust was leaking on any parts effected by heat it could be.
When you pull on the starter does the compression feel strong , If you lift up the saw by the starter rope does the compression of the saw hold the saw up or does it drop letting the rope out. I am still wondering if there is any damage to the rings or cylinder and piston.
I don't think it is the carb gummed up with oil or an air leak , Top end or electronics is my guess but I donot know enough to tell you anything for sure. Is it possible the hot exhaust was escaping toward the electronics.
Just some more ideas.