How do you "tune up" a hard-to-start Craftsman 18" chainsaw

On Sat, 21 Aug 2010 19:08:40 -0500, The Daring Dufas wrote:

> It's not rocket surgery. 8-)

LOL!

On Sat, 21 Aug 2010 19:08:40 -0500, The Daring Dufas wrote:

> All reciprocating (piston) engines are basically air pumps.

Ah. Now I understand what you're saying. Thanks for the details.

I tried blowing about 50psi compressed air into the spark plug hole ...
with mixed results (my compressor doesn't go higher than that).

- If the piston was at the top, it fluttered (see details below).
- If the piston was at another spot, it blew out the exhaust.
- If the piston was at yet another spot, it blew out the carbeurator.

But it never did run the thing (I think because of the pull-cord clutch
mechanism because it 'looked' like it wanted to spin but couldn't spin.
Probably because it wasn't fast enough to make the pull-cord clutch
disengage.

So, I think the "fluttering" was the piston trying to turn the crankshaft
but it couldn't because of the pull cord. I guess I could remove the pull
cord and test it without the pull-cord clutch...

On Sun, 22 Aug 2010 01:29:48 GMT, notbob wrote:

> Size of the cylinder has no bearing on amount of pressure.

That makes sense. I practically filled the thing with carb cleaner today.
I'm letting it all dry out before I try again.

If this last ditch effort doesn't work, plan B is to bring it to a shop for
an estimate.

Plan C, is to buy a NON-CALIFORNIA chain saw on the net. Can you recommend
a good place to buy chain saws (NON CALIFORNIA EMISSIONS) that actually
have adjustable "L" low and "H" high screws for the carb?

On 8/22/2010 7:15 PM, SF Man wrote:
> On Sat, 21 Aug 2010 19:08:40 -0500, The Daring Dufas wrote:
>
>> All reciprocating (piston) engines are basically air pumps.
>
> Ah. Now I understand what you're saying. Thanks for the details.
>
> I tried blowing about 50psi compressed air into the spark plug hole ...
> with mixed results (my compressor doesn't go higher than that).
>
> - If the piston was at the top, it fluttered (see details below).
> - If the piston was at another spot, it blew out the exhaust.
> - If the piston was at yet another spot, it blew out the carbeurator.
>
> But it never did run the thing (I think because of the pull-cord clutch
> mechanism because it 'looked' like it wanted to spin but couldn't spin.
> Probably because it wasn't fast enough to make the pull-cord clutch
> disengage.
>
> So, I think the "fluttering" was the piston trying to turn the crankshaft
> but it couldn't because of the pull cord. I guess I could remove the pull
> cord and test it without the pull-cord clutch...

If you'll look up how a two cycle engine works, you will understand
why the air came out where it did. The position of the piston is
what acts like the valves in a four cycle engine by uncovering the
intake port or the exhaust port. If the reed valve is good, there
shouldn't be any air coming out of the carburetor. Here's a link to
an animation that shows how a two stroke engine works:

http://science.howstuffworks.com/tra...wo-stroke2.htm

http://preview.tinyurl.com/33qdr5p

A bad reed valve could keep it from running on compressed air.

TDD

On 2010-08-23, SF Man > wrote:

> Plan C, is to buy a NON-CALIFORNIA chain saw on the net. Can you recommend
> a good place to buy chain saws (NON CALIFORNIA EMISSIONS) that actually
> have adjustable "L" low and "H" high screws for the carb?

Sorry, but I've had little to no experience with chainsaws and
2-stroke yard tools, despite their being the same engines. In fact, I
had a terrible time with the chainsaws and gas trimmers I inherited
when my brother passed away. I couldn't get any of them to start,
either, mainly cuz they were all junk, with cracked primer bulbs and
hardened broken fuel lines and cracked plug wires. There's some real
crappy merchandise being foisted off on the public, these days.

nb

On Sun, 22 Aug 2010 17:18:49 -0700, SF Man wrote:

> On Sun, 22 Aug 2010 01:29:48 GMT, notbob wrote:
>
>> Size of the cylinder has no bearing on amount of pressure.
>
> That makes sense. I practically filled the thing with carb cleaner
> today. I'm letting it all dry out before I try again.
>
> If this last ditch effort doesn't work, plan B is to bring it to a shop
> for an estimate.

Check that the gasket between the carb and engine is good, that the carb
is bolted on tightly, and that the crankcase cover[1] is bolted on
tightly and with a good seal. On most of these engines the carb's fuel
pump runs from crankcase pressure, so if there are any leaks in the
system all sorts of strange things can happen - after ruling out spark
and fuel line/filter, I'd try there next I think.

Also pull the flywheel; it might be that the flywheel key has sheared and
the timing's out a little - maybe not enough to stop it running (with a
loss of power, but that might not be noticable), but enough to make it
hard to start.

[1] taking the cover off for a moment just to see if the bore is damaged
might not be a bad idea, either.

(re. compression, I posted here about a 4-stroke mower engine earlier in
the year; that one turned out to be compression loss due to bore damage,
even though it felt like it had "enough" compression when I stuck my
thumb over the spark plug hole)

cheers

Jules

"SF Man" > wrote in message
...
> On Sun, 22 Aug 2010 01:29:48 GMT, notbob wrote:
>
>> Size of the cylinder has no bearing on amount of pressure.
>
> That makes sense. I practically filled the thing with carb cleaner today.
> I'm letting it all dry out before I try again.
>
> If this last ditch effort doesn't work, plan B is to bring it to a shop
> for
> an estimate.
>
> Plan C, is to buy a NON-CALIFORNIA chain saw on the net. Can you recommend
> a good place to buy chain saws (NON CALIFORNIA EMISSIONS) that actually
> have adjustable "L" low and "H" high screws for the carb?

I would recommend you go straight to "B". An honest saw mechanic can either
fix this
rascal quickly, or he can tell you it isnt worth fixing.

I never bought a saw on the net. My first chain saw was an Echo, and it was
a heck of a
good saw. Then I bought a Husqvarna (also a great saw, stolen by a couple
of drugheads), and
then a replacement Husqvarna.

I dont know if an internet company CAN ship a noncomplying saw to
California.

Note that some saws have what they used to call 50 hour engines. That is
about the life
expectancy of them.

On Mon, 23 Aug 2010 09:51:13 -0500, hls wrote:
> Note that some saws have what they used to call 50 hour engines. That
> is about the life expectancy of them.

Or you get a "Friday engine", assembled by someone who is itching to get
away for the weekend and so not paying as much attention to their work as
they should :-(

On Sun, 22 Aug 2010 20:30:10 -0500, The Daring Dufas wrote:

This is the California Poulan owners manual for my Craftsman chain saw.
http://www.billious.com/ipls/pwe/pp3...2005-06-03.pdf

Unfortunately you can't adjust anything when/if the carb gets clogged.

It's California's way of stimulating the economy while saving the
environment.

It either works or you throw it away and buy a new one every two years.

Stihl chainsaws are top rated chainsaws.
Last year, a guy who lives across the street from me borrowed my old
Remington electric chain saw.He told me he is an old country boy and he
knows all about chainsaws.HA!, he couldn't even figure out how to turn
it on, I showed him half a dozen times and also how to keep the chain
adjusted properly.About half an hour later, he brought it back over
here.The chain was off the bar and all snaggled up and a little metal
plate which keeps the chain from flying off of the clutch was broken.He
broke my chainsaw.
I have owned a few gas engine chainsaws before, but I never broke any of
them.

Last year, he couldn't figure out how to find the oil drain plug on the
bottom of his lawn mower.He pushed his lawn mower over here, he said,
Show me where that oil drain plug is!
Only took me a few seconds to show him.He was to lazy to wipe his hand
under there and look for that oil drain plug.
cuhulin