Stihl ts 420 not starting

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Lester Gillett

Lester Gillett

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Mar 21, 2015
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Beside the ts 400 I have a ts 420 that will not start. I checked the compression and it was 90 psi. Not sure if this is good or not.
I checked the pump and it files up so i know gas is getting in to the carb. I then checked for spark with a light tester and it looked
ok, just not to bright. so I unplugged the switch and the same looked. No I sprayed starting flued in muffler still not starting. Now
when i remove the plug it is not wet ? So i put a coil from one that runs and it still will not start. These concrete saw are about to drive me crazy.

HELP
 
frank_

frank_

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a drop of oil down the plughole should raise the compression enough to run for a while
i did a 410 that the crank seal had blown out under the flywheel recently (non starter) it would run with some fuel down the plughole
i definitely prefer the 400,s
 
Lester Gillett

Lester Gillett

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Joined
Mar 21, 2015
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Independence
It still will not start, changed the coil and plug wire. Should get a new compression tester to day and see what it show's. Also
going to put a few drops of oil to see if that raise the compression. I guess next will be the seals or carb and see what that does.
 
sawfan123

sawfan123

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It still will not start, changed the coil and plug wire. Should get a new compression tester to day and see what it show's. Also
going to put a few drops of oil to see if that raise the compression. I guess next will be the seals or carb and see what that does.
And 120 is bare minimum. You have to remove the compression release if equipped.
And putting all your trust in compression reading is not a good idea.
Removing the muffler might be better.
You can see the real wear in the ring grooves.
 
Lester Gillett

Lester Gillett

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I received the compression gage and I checked the compression. Reads140 psi. Now with all I have done all that I haven't done is the seals and carb. Here is the gage I bought.20211005_152617.jpg
 
Lester Gillett

Lester Gillett

ArboristSite Member
Joined
Mar 21, 2015
Messages
87
Location
Independence
Will I guess I am getting to old to start these saws. I gave the saw to one of the workers and it started up.
Will just work on them and let them start it up. Then I can adjust the carb so they will run not to lean. Thanks
for all the help.
 

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