Non GS, non mo'cycle. 2 cycle engine

[tkent02]

If it still goes thump thump thump there is enough compression, maybe not enough to idle well but it should start and run.

Can you tell how the fuel gets into the engine? maybe something in there is clogged?
A kinked fuel line is very possible.
I'm always getting sawdust in my gas tank, could this have caused blockage somewhere?
Is the fuel really old? Fuel could have evaporated out, leaving too much oil in the mix.

And, the fuel should be mixed at the ratio the engine was designed for, to mix 50-1 in an engine set up for 16-1 would make the fuel mixture very rich, and to go 16-1 on an engine designed for 50-1 would make it run very lean.

It is opposite of what you would think, but the oil does not burn as fuel, just takes the place of some of the fuel, leaving less of it. So too much oil in the fuel equals too lean, and can burn things up even with all that oil.

[Redman]

It will run for a bit if I drip fuel in carb, so I do not suspect ignition problem.

16:1 is what is listed in original owners manaul (from 1982). I suppose that recomendation is based on the metallurgy of the time, but maybe is based on the oil of the time. But anyway, that is what I would contunue to use. I do notice that more recent 2 cycle engines use 32:1 or 50:1 (but that is a different discussion).

I can find lots of parts for this model on a Sears parts website for not too terrible price. DOnt know what specific Poulan model it is to look for parts that way. But, yah, maybe that shop cant get the parts thru thier normal supplier.


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[tkent02]

Yes you can check compression
two strokes get scores in the cylinders quite often, may or may not be a problem.
He may know he can't get parts

Does it use suction? I thought they has a little fuel pump that is powered by engine vibrations?

[Agemax]

have you checked the plug? have you still got a spark and is it wet with fuel? 16:1 sounds like a very rich fuel/oil mixture to me, especially if you are using modern 2 stroke oil

[Redman]

2 cycle chain saw engine question.

Dont want to post in off topic because I dont want to know if if I am too conservative or if I am too liberal. And I already know I am somewhat ignorant of this subject.

Basic question: I can take a compression test on a 2 cycle engine, right? I have a compression tester that has a couple different adapters for different sizes of spark plugs.

Situation: Have had chainsaw new from 1982, Craftsman/Poulan.
Sat unused for 15 years (in attatched garage). Seemed to have have good compression based on my observation of it going fump-fump-fump when pulling the cord.
And the ignition made spark.
I cleaned out the tank, replaced the fuel filter in tank. Took apart the carb and the diaprahams looked good. Squired carb cleaner in various orifaces. Replaced the air filter. Replaced the bar and chain (were rusty). And got it to run, and run well. Used it for about 20-30 minutes on one occassion.
Is older design, so is 16:1 mixture, and that is what I used, blueish smoke exhaust and all.
And Then went to use it again, and cant get it to start.
Will start and run for a bit if I drip gas in carb. Still seems to have the same fump-fump-fump when pull the cord. Carb diaphrams still looked good.
Took it to an indepandant small engine shop.
They said cyclinder looked good at first glance (service manager; when I first took it there took off muffler and looked, said it looked real good) but now on closer inspection (technician) says it has one deep score in it that makes it so will not pull gas up to carb. And deemed it not worth repairing.
Huh?
That make sence?
Has good enough compression to run, but not eneough suction to pull gas to carb...? I dont fully understand what developes the suction anyway.

I suspect maybe they just didnt want to bother with trying to get the older parts.

Any comments?