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Chain saw question,,,

Coastiejoe

Coastiejoe

Moderator
Moderator
Father in law asked me to look at his Saw that would not start.

"Feels" like it has compression, it does have spark and it does have fuel.

Drained and refilled fuel tank, removed carb entirely, placed thumb over suction hole and only minimal suction in my opinion. Pulled plug and looked at piston. Looks ok from what I can see and travels smoothly.

So, pretty sure I have a valve issue. That said, not sure how small two stroke valves work.

Is it worth opening up or not is the big question?

Thanks in advance.
 
It probably has reed valves, unless it's a SeaDoo chain saw, the it would have a rotary valve, LOL. I would go ahead and open it up, what have you got to lose?

Lou
 
What was the initial problem with the saw? I realize it will not run; but was that because it was sitting for a while without being run, or did it just quit one day while in use? Things like saws sometimes only get used once a year and nobody thinks to do any maintenance to them until it's needed one day.

In my experience, it is usually the carburetor; unless the saw has gotten a lot of use and is beat up. Not sure what brand it is, but most of these small 2-stokes use zama carbs and they are still kind of a mystery to me. Not much moving parts in them, and when they don't work I usually just end up replacing them.

A good test is to bolt everything back together, and to make sure it is not flooded (with the spark plug out) pull then engine over a few times upside down (spark plug hole toward ground) and see if anything comes out. There may be a bunch of oil/gas sitting at the bottom of engine and you need to get that out. Put everything back together and see if it will start, if not try using starting fluid, spray it on the air filter and/or in the air intake. See if it will start with the throttle wide open. If it does want to run with starting fluid you got carb problems.

You can try to take the carb apart, soak it in cleaner over night etc. I have never had much luck resurrecting one of these tiny carbs. If that doesn't work, just go and get a new carb off the internet. They are relatively inexpensive and should be easy to find.

Good luck!
 
Hit it with some starter fluid... and get it to make some noise.


The carbs on small lawn equipment, is the same type as we run on our skis. They are regulator carbs, and don't have a float. So... look at all the same stuff. Needle/seat... pop-off... jets... ports... high speed check valve.... (and most) the high and low needles.


As lou said... the engine has a high probability of being a reed engine... or just a simple piston port. In all my years of playing with little engines... I've only seen one chain saw with a rotary valve. (it had a Kawasaki engine)
 
It is a Homelite chainsaw.

Initial symptom, his son used it.. LOL

It was running, stopped running, son put fuel in it (no way to know if it was correct fuel mixture at this point), didn't start, bough a new one to complete his job, returned the non-running saw to dad... Perfect...

I tried the starting fluid thing early on once I saw it had spark. It is the original plug but it does spark. Might get a new one to ensure quality of spark.

Though the carb may be totally plugged as it was a year with whatever fuel was in it. Figured it may have gummed it up and not allow any air/fuel to pass through. Removed the carb and sprayed starting fluid directly into the cylinder via the carb hole, no joy...

Poured fuel mixture into the cylinder via spark hole thinking it would help to both lube it a bit and help the rings seal a bit better in hopes of better compression. Still no joy...

I'm guessing if the new plug makes no difference I will have to open it up to see what the valves are doing if anything. Off hand I am guessing they are doing nothing as I have fuel and spark and the piston is working. So it really has to come down to the quality of the compression, (I'm thinking)...
 
If it didn't run/start on starter fluid... then that engine is dead. It was probably run with straight gas. You may have had a puff of air on your finger... but if the piston melted over the rings... it won't seal, and doesn't really have any compression.
 
Thanks all, will check compression but it isn't looking good.

I feel pretty confident that the son wiped it out.

Thanks ,,,,
 
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Anything around or under 100psi is no good. Should be ideally 140-150 (sound familiar :-D)

PM me for further stuff- I've been around small engines one or two... thousand times.
 
SMC, Chuckled.

Thanks. Going to relax for the holiday. Will check it on Tuesday. Thanks much. Will let you know.
 
Ive been sick as a dog since Friday, Ive only left the house once. I already told the boss to not expect me Tuesday! Now Im gonna have to call out sick next week to make up for missing this weekend
 
That makes perfect sense to me. Not your fault you were sick in the weekend.

I like your way of thinking,,,
 
Yep, I agree with these guys, check compression before you do anything else. I bet he ran straight gas a cooked the engine too. My bro-in law owns a lawn mower repair shop and sees it all the time. If not, I'm sure it is a carb problem. If thats the case, from what he (bro-in law) tells me and first hand experience from my own, alot of times it is way easier and sometimes about the same price to buy a whole new carb for them instead of rebuilding/fooling with the old one. Oh and if it is fried tell him to buy a stihl, echo, or shindaiwa, and not let his son use it! :thumbsup:
 
Coastiejoe said:
It is a Homelite chainsaw.

Though the carb may be totally plugged as it was a year with whatever fuel was in it. Figured it may have gummed it up and not allow any air/fuel to pass through. Removed the carb and sprayed starting fluid directly into the cylinder via the carb hole, no joy...

Poured fuel mixture into the cylinder via spark hole thinking it would help to both lube it a bit and help the rings seal a bit better in hopes of better compression. Still no joy...

...
Click to expand...

Does "no joy" mean absolutely no firing or just that it does not keep running?

I have picked up numerous chainsaws, generators that will not run and have been able to get several to run by squirting carb cleaner into the fuel intake line ... of course I have found a lot of fuel intake lines rotted off completely and some that just taking off the carb and cleaning it out gets things working.

The kid should have given Dad the working saw and kept the non-working one .... I know, dream on!

Rod
 
RodInEscondido said:
Does "no joy" mean absolutely no firing or just that it does not keep running?

I have picked up numerous chainsaws, generators that will not run and have been able to get several to run by squirting carb cleaner into the fuel intake line ... of course I have found a lot of fuel intake lines rotted off completely and some that just taking off the carb and cleaning it out gets things working.

The kid should have given Dad the working saw and kept the non-working one .... I know, dream on!

Rod
Click to expand...

No-joy means, no good,, it never fires. Carb removed, able to squirt direct into inlet side and no attempt to run. This is why I assume ibis a compression issue. I'm busy for the next couple if days. Will do a tear down when I get back home.

I agree, kid should have given up the good saw. I would have.
 
as an arborist myself Joe sounds as if its ran with incorrect fuel mixture, or maybe straight fuel, which I myself did once upon a time, that saw basically did the same as your saying here, loss of compression/firing and such. If that's the case then I'm sure you pretty much know what you're in for. homelites are to me cheap throw away saws unless you're just going to use them now and then. Good luck let us know what you find out?
 
shucky said:
as an arborist myself Joe sounds as if its ran with incorrect fuel mixture, or maybe straight fuel, which I myself did once upon a time, that saw basically did the same as your saying here, loss of compression/firing and such. If that's the case then I'm sure you pretty much know what you're in for. homelites are to me cheap throw away saws unless you're just going to use them now and then. Good luck let us know what you find out?
Click to expand...

He ran it with straight fuel...

It is dead.. LOL
 
You can do a compression test, keep pulling the rope till your tester stops rising. Most will blow 120psi. Another basic quickie test with plug installed is the saw should not immediately drop to the ground if you hold it by the starter rope handle.

Remove muffler and inspect piston skirt for scoring.
 
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The sad part is, the saw is probaly ancient as chain saws go. I have the almost exact chain saw in the garage. It's not worth putting any money into it! For twice what you would put into it you can have a brand new saw! I work my chain saws big time! I take care of them. But, you reach a time when they are DONE. I have run them my entire life. I can tighten a chain saw blade or pull a spark plug with the best of them! A truck load of wood is my families normal end point.
 
Well it's a Homelite so yes questionable. I have a collection of old Poulans some of which were resurrected back from the dead and worth the trouble IMO. My favorite is the SD25A model trim saw with chrome plated cylinder bore for some reason, it feels at home in my hands.
 
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