Compession test

[Eljay]

I have been trying to rescue a Poulan 3400 that would not start. It seemed to have very little compression so I installed new rings. Compression is a lot better but it still won't start. Spark is fine and it won't even pop with a shot of ether. What is a reasonable figure for compression as measured with a compression tester. Any other ideas?

[Rocky_J]

Since the advent of the EPA restrictions on small equipment 20 years ago, I've seen a boatload of them quit running due to plugged exhaust. To meet EPA emissions requirements, they choke down the exhaust to reduce output. Then add a spark arrester screen and a couple years running on cheap two cycle mix and the carbon buildup plugs off the exhaust to where it can't run.

Just a shot in the dark, but one of the basics that gets checked on everything I look at because it is so common. I got a free leaf blower my neighbor threw out last year. Dug it out of his garbage can, removed the plugged spark screen and opened the exhaust a little, fresh fuel and she fired right up.

If it's breathing ok then I'd check the carb next.

[Eljay]

Rocky,
You were right on the money. I removed the spark arrestor screen and the saw started on the first pull. The screen was completely clogged. The saw now runs like a champ.
I am inclined to do without the screen. Comments?

[Rocky_J]

Unless you are working in extremely dry woods under severe fire conditions and under direct control of a government agency that will come inspect your saws, then throw the screen away.

[sablatnic]

Talking clogged exhausts, recently I got a Stihl 020, completely plugged by pupae, probably ants. Is it a common defect, or is it a first?

[beenthere]

Just remember when to put the screen back in (after taking it out)   

I forgot mine was out when I picked up the 2nd course of GOL (Game of Logging). The instructor goes over everyone's saw, like an inspection.  I's docked for no screen, but it still lies on the bench. Another docking for having some rakers too high (it was a brand new chain so was factory issue  ).   
(note: The nice looking girl in the course didn't get any points off  ).

[sharkey]

Eljay,
Ive seen mud dabber wasps but never ants.  I guess anything that likes grease and oil will find some in a saw muffler!

Best wishes,
Bob