2 cycle compression ......

[Steve B]

I have a 21cc hedge trimmer. A Craftsman. It hasn't run for a while, but
the guy swore it was running when put up.

I put new gas in it, and checked the obvious. It needed a new on/off
switch. It has spark. I can't get it to pop, even with shooting a little
gas into the carb, or on the sponge air cleaner.

When I pull the start rope, there isn't very much "POP" at all. I mean
resistance that would come from good compression, or from firing and
igniting the gas/air mixture.

Just how much "POP" should be present, even if you have the switch off, and
aren't trying to start it, but just basically see how much compression it
has? I call "POP" that instantaneous resistance on the pull rope where it
would hit TDC, or fire with a spark. Does two strokes not have the "POP"
that four strokes have because of their different configuration?

Tomorrow, I'll pull the carb and see if there's anything obvious there. The
primer bulb worked, no leakage, and filled up, presumably feeding gas to the
carb.

Steve

[Tony Hwang]

Hi,
Take a look at the spark plug. To check a compression I remove plug and
plug the hole tight with chewed paper ball. When you pull the cord, it
should pop out. Is choke working? Try new spark plug or heat it on the
range heater and make it dry. Hope you did not mix in too much oil.

[hr(bob) hofmann@att.net]

If this is a 2-cycle engine, it make take a few pulls to get enough
oil into the unit to raise the compression. you could also put a 1/2
teaspoon oil into the engine thru the spark plug opening, pull the
starter a few times to spread the oil around and then put the plug
back in and see if the compression seems to be higher. You could also
use some starting fluid.

[Steve B]

"Tony Hwang" <drag...@shaw.ca> wrote in message
news:%h8cr.43880$M%7.2...@newsfe10.iad...

Plug is absolutely new and dry. Even when I shoot some gas into the carb
opening with a syringe. Even with shooting a small amount of gas into the
plug hole, reinstalling plug, and pulling cord. I suspect I need to take it
off tomorrow and see what's up.

I got an edger going today, a 3.5 hp Briggs, but it doesn't run very well,
and the thing will only run with both jets at about 3/4 turn open. Can't
get it to run up to very high rpm by adjusting the jets. Took off the
diaphragm cover, but just the cover. There was sand. I didn't have a
replacement diaphragm, and that one was on there pretty tight, so chose to
just leave it alone, thinking it might run. Obviously, I need to get a carb
rebuild kit and go through it. First, though, I'll take a razor knife and
see if I can get the diaphragm/gasket off, and clean behind it, then reuse
it.

With these little carbs, just a little bit of junk will make a big
difference. They're like working on watches.

Steve

[Teddy]

On 3/26/2012 8:45 PM, Steve B wrote:
> I have a 21cc hedge trimmer. A Craftsman. It hasn't run for a while, but
> the guy swore it was running when put up.
>
> I put new gas in it, and checked the obvious. It needed a new on/off
> switch. It has spark. I can't get it to pop, even with shooting a little
> gas into the carb, or on the sponge air cleaner.
>

Another case of ethanol damage?

http://www.biztimes.com/article/20120326/ENEWSLETTERS02/120329786

[notbob]

On 2012-03-27, Steve B <ste...@gmail.com> wrote:

> would hit TDC, or fire with a spark. Does two strokes not have the "POP"
> that four strokes have because of their different configuration?

Sounds like you want to know if there is enough compression in yer
2-stroke. When I was a motorcycle mechanic, lo these many yrs ago,
the rule of thumb for both 2 and 4 strokes was: Pull the spark plug.
Put yer thumb firmly over the plug hole, make sure the throttle is
wide open, and cycle the engine. If there is enough compression to
blow air past yer thumb, that's good enough. If not, you need a
rebuild. Typically a bore job and new rings.

nb


--
Fight internet CENSORSHIP - Fight SOPA-PIPA
Contact your congressman and/or representative, now!
http://projects.propublica.org/sopa/
vi --the heart of evil!

[Steve Barker]

not likely. LMAO!

--
Steve Barker
remove the "not" from my address to email

[Hank]

On Mar 26, 9:32 pm, "Steve B" <ste...@gmail.com> wrote:
> "Tony Hwang" <drago...@shaw.ca> wrote in message

Compression may be the problem, but you have to run a compression
check to verify. Plugs can be what we call "gas fouled". It may be
new, look clean and may even produce a little spark. But more times
than not, a person usually floods a 2 stroke to the point of "gas
foulding a plug". They think that they can't put too much gas in to
make if fire and usually there is so much gas laying in the crankcase,
it is near impossible to get the air/fuel mixture into the flammable
range.

Here's my suggestion...........

Remove the plug and pull the start cord a few times and let it sit,
come back an hour or so later and pull it a few more times. This
should remove any gas that is in the crankcase. Let it sit overnight
with the plug out. This will let any gas in the crankcase to dry out.
The next day, install a NEW plug after squirting a little juice down
the plug hole. Don't choke, it should fire if there isn't a
compression problem.

Hank <~~~~~ thinking it is badly flooded

[Bill G]

"Teddy" <te...@internet.com> wrote in message news:4f712003$0$2582$c3e8da3$f5af...@news.astraweb.com...

If it is stored with ethanol gas for more than 90 days you will often find a corroded carburetor.
Not really a big deal, a new carb is prolly only $50 or so. Yawn.

[ransley]

A weak spark may not spark at all under compression and fuel load,I've
had that happen on ignition modules or coils nearing failure. Even a
bad plug can do that. Is spark weak. For 10-15$ get a compression
tester, if you have other old motors it will get good use, don't guess
on compression, the exact pounds show how much engine life is left,
weak compression weak spark could make it not fire.

[Art Todesco]

On 3/26/2012 8:45 PM, Steve B wrote:

Last year in August, I bought a little used but older Stihl chainsaw
from the local Habitat for Humanity Thrift Store. It ran good. It was
very dirty and needed a cosmetic cleaning job. Seemed to have good
compression. And, it was only $50. I used it once in December and it
started and ran great. This year, I tried to start it and nothing.
Well, ok, there was an occasional pop, but few and far between. I
checked the plug and it was wet. Dried it off and tried and tried and
nothing. Emptied the gas and put in clean gas/oil. Stihl nothing :) I
then put in a quick squirt of starting fluid in the plug hole,
reinstalled the plug and tried again. After maybe 10 pulls, it started
without the choke (only on or off) and full open throttle. It seems ok
now. I used it the next day. The 1st time it took about 6 or 8 pulls
before it started. After that, only one pull. BTW, I think this thing
had the original chain, apparently never sharpened and still very sharp.
Of course I can't tell for sure, but it everything points in that
direction. So it must have been owned by someone who just used it a few
times, spending most of it's life on the shelf with all the oily sawdust
just left there.

[Stormin Mormon]

Retail $183.99, so the carb is about 1/3 the cost of the machine. That woke
me up. No yawns here.

http://www.craftsman.com/shc/s/s_10155_12602_Lawn+&+Garden_Yard+Power+&+Equipment_Hedge+Trimmers?storeId=10155&sName=Hedge+Trimmers&vName=Lawn+%26+Garden&psid=64x732&cName=Yard+Power+%26+Equipment&catalogId=12602&sid=ISx20110429x00001&i_cntr=1332855998627#viewItems=12&pageNum=1&sortOption=ORIGINAL_SORT_ORDER&&filter=Power+Type|Gas&lastFilter=Power+Type

http://tinyurl.com/d4lld7r

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Bill G" <bi...@home.now> wrote in message
news:jks39...@news6.newsguy.com...

[Stormin Mormon]

Ether in the spark hole dries the oil out of the cylinder wall. Can result
in piston locking up, or worse, thrown piston rod. Happened to me.

My Dad's generator didn't start. During a power cut, of course. A "helpful"
neighbor sprayed ether in the spark hole. Locked up the piston. Dad went and
bought another generator.

Dad gave me the broken generator. I freed the piston, and negelected to
reoil the cylinder bore. The motor started, ran half a second, and threw a
piston rod. Turned a $500 generator into a $75 ebay sale "as it". I was
disappointed.

Ether in the spark hole, at your own risk.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Art Todesco" <acto...@yahoo.com> wrote in message
news:jksem8$59o$1...@dont-email.me...

[Jules Richardson]

On Tue, 27 Mar 2012 03:36:21 +0000, notbob wrote:
> Sounds like you want to know if there is enough compression in yer
> 2-stroke. When I was a motorcycle mechanic, lo these many yrs ago, the
> rule of thumb for both 2 and 4 strokes was: Pull the spark plug. Put yer
> thumb firmly over the plug hole, make sure the throttle is wide open,
> and cycle the engine. If there is enough compression to blow air past
> yer thumb, that's good enough. If not, you need a rebuild. Typically a
> bore job and new rings.

I've been told that one too in the past (and used it - it is a good
test). I did have a 10HP engine which passed the 'thumb test' though but
still didn't have enough compression to run; that one turned out to have
major damage toward the bottom of the bore, with minor piston damage too
(but rings were intact).

The long-term correct fix was a rebore, but the emergency redneck fix
(more to see if it would even work than anything) was to patch the damage
with epoxy*. Two years later it's still running like that... :-)

* can't remember what I used now, but something rated for high temp and
oil contact.

cheers

Jules

[notbob]

On 2012-03-27, Jules Richardson <jules.richa...@gmail.com> wrote:

> * can't remember what I used now, but something rated for high temp and
> oil contact.

Not familiar, it being decades since I was a motor wrench.

One quickie trick is to squirt some heavy motor oil (50-60wt) in the
sparky hole to give the rings some temp sealing power. It will go
away, but often gives jes enough seal to get the engine running.

[Stormin Mormon]

I've heard of using a squart of two stroke oil, which burns more cleanly.
Same idea.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"notbob" <not...@nothome.com> wrote in message
news:slrnjn3qhi...@nbleet.hcc.net...

[Mr. Austerity]

I've messed with a lot of the trimmers. Most of them now days are not
for this world long. Keep messing with it and you will get it running
but don't expect to much. The carbs are set to run as lean as possible
nowdays with very limited adj to richen them, which is why half of them
have to be run with the choke partially on.
Any chance someone ran it without the oil mixed with the gas?

[Harry K]

On Mar 26, 6:32 pm, "Steve B" <ste...@gmail.com> wrote:
> "Tony Hwang" <drago...@shaw.ca> wrote in message

Could be it was straight gased, pull the exhaust and check for scoring
on hthe pison/jug.

Harry K

[Bob-tx]

"notbob" <not...@nothome.com> wrote in message
news:slrnjn3qhi...@nbleet.hcc.net...

> On 2012-03-27, Jules Richardson <jules.richa...@gmail.com> wrote:
>
>> * can't remember what I used now, but something rated for high temp and
>> oil contact.
>
> Not familiar, it being decades since I was a motor wrench.
>
> One quickie trick is to squirt some heavy motor oil (50-60wt) in the
> sparky hole to give the rings some temp sealing power. It will go
> away, but often gives jes enough seal to get the engine running.
>
> nb

Here is a trick that seems to be little known, but one that has worked for
me at times over the many years I owned a small engine shop.

For a vertical cylinder engine, remove the spark plug - rotate the piston to
TDC (Top dead center) and then pour in paint thinner. It dissolves carbon
on piston rings and valve seats. Let stand overnight. Then drain oil and
refill with new oil. This will often bring compression up from virtually
nothing to a workable engine. Not a permanent fix, but gets you by. For a
horizontal piston (vertical crankshaft), tip the engine on its side with the
spark plug up.

Bob-tx

[Steve B]

Went to the local small engine repair place today to get a couple of other
parts for another machine. He checked the compression, and it was an
astounding 45 psi. So, apparently there are major problems in the engine,
probably rings. Not sure whether to dump more $$$ into this, or just junk
it and get the electric used ones at yard sales for $15.

Oh, wait, I think I know the answer to this one.........

Steve

[Jules Richardson]

On Tue, 27 Mar 2012 17:17:31 -0700, Steve B wrote:

> Went to the local small engine repair place today to get a couple of
> other parts for another machine. He checked the compression, and it was
> an astounding 45 psi. So, apparently there are major problems in the
> engine, probably rings. Not sure whether to dump more $$$ into this, or
> just junk it and get the electric used ones at yard sales for $15.

Pull the head on it and check the bore for damage - typically on these
smaller engines the head gaskets are quite meaty and will come off clean
(and can be reused). Unless, of course, it's a head gasket problem in
the first place...

> Oh, wait, I think I know the answer to this one.........

I don't know, I don't like electric stuff - too much of a pain to run
cords everywhere. On the other hand, gas prices... :-)

cheers

Jules

[Art Todesco]

Not to say that it won't dry out oil in the cylinder wall, I don't know,
but .... I've used ether in most of my small engines at one time or another
and haven't any problems.

[JIMMIE]

You can borrow a compression tester from places like Auto Zone for free, just have to leave them a deposit. Bad compression doesnt mean the engine is damaged it may just mean the engine has dried out from setting up and could use a squirt of oil,common. Ignition could be weak even if you see a spark. Make sure you are using the right oil-gas ratio for that engine.

Jimmie

[harry]

The thing you thinkis a carb may not be. A lot of these micro-motors
have minature petrol injection. It works by means of a diaphragm
pwered by crank case compression.
The advantage is, it works any way up.
The diaphragm can split. the two tiny check valves can leak.

[cl...@snyder.on.ca]

Which WILL wash the oil off the cyl, killing the compression if it
doesn't start right away.

[ransley]

I think it needs alot more than 45 to ever have run, meaning it could
have been run on gas with no oil for a bit, maybe rings wold fix it,
maybe other bearings are bad

[Hank]

On Mar 29, 8:58 am, ransley <mark.ransle...@gmail.com> wrote:

>
> I think it needs alot more than 45 to ever have run, meaning it could
> have been run on gas with no oil for a bit, maybe rings wold fix it,
> maybe other bearings are bad

Running a compression check on a small 2 stroke engine can be very mis-
leading because of the SMALL AMOUNT OF AIR (THINK VOLUME) that is
being compressed goes into the hose of the gauge and is then expanded
creating less PSI.

I would do what I suggested earlier before I would pronounce it DOA.

Hank

[denni...@gmail.com]

On Tuesday, March 27, 2012 8:59:03 PM UTC-4, Jules Richardson wrote:
> Pull the head on it and check the bore for damage - typically on these
> smaller engines the head gaskets are quite meaty and will come off clean
> (and can be reused). Unless, of course, it's a head gasket problem in
> the first place...

It's a 2-stroke weedeater. 99.99% chance that it does not have a separate head. The head and cylinder are one piece and bolt to the crankcase. Nearly all small 2-stroke engines have one-piece "jugs."

[cl...@snyder.on.ca]

On Wed, 28 Mar 2012 09:19:19 -0700 (PDT), harry <harol...@aol.com>
wrote:

Those are still carbs - not injectors. They are "regulator carbs"
with a diaphragm instead of a float, and a pulse powered fuel pump
(which has another diaphragm)

[cl...@snyder.on.ca]

Stange, NONE of the numerous 2 stroke engines I have floating around
have integrated jugs. They ALL have removeable cyl heads.

[Steve B]

>>
>>The thing you thinkis a carb may not be. A lot of these micro-motors
>>have minature petrol injection. It works by means of a diaphragm
>>pwered by crank case compression.
>>The advantage is, it works any way up.
>>The diaphragm can split. the two tiny check valves can leak.
> Those are still carbs - not injectors. They are "regulator carbs"
> with a diaphragm instead of a float, and a pulse powered fuel pump
> (which has another diaphragm)

I have a vintage Honda FourTrax, the first year they were made. It wasn't
ridden much, then restored by Grandpa for his kid at a cost of $900. Tires,
and "stuff". Kid got busted for drugs, so Grandpa sold FourTrax. I picked
it up.

That early model has an electric fuel pump, as the carb is higher than the
gas tank. It is a damn nightmare. I finally went to a friend who works on
them, and asked what to do, as it was always acting up.

He sold me a Mikuni pulse operated fuel pump. All you need is a vacant
vacuum port on the carb, and the pulsation works a small diaphragm.
Marvelous concept, except for the small detail of no port on that Honda.

So, anyway, I got the electric one working. Hope it doesn't act up out in
the bush.

Sold the Mikuni to a friend who has a race bike, and he installed it on his,
and it fixed his fuel starvation caused fluttering.

The thing is elegantly simple. Three little nipples... vacuum, gas in, gas
out. Bolt it on anywhere.

Steve

[Hank]

On Apr 2, 5:49 pm, "Steve B" <ste...@gmail.com> wrote:

>
> I have a vintage Honda FourTrax, the first year they were made.  It wasn't
> ridden much, then restored by Grandpa for his kid at a cost of $900.  Tires,
> and "stuff".  Kid got busted for drugs, so Grandpa sold FourTrax.  I picked
> it up.
>
> That early model has an electric fuel pump, as the carb is higher than the
> gas tank.  It is a damn nightmare.  I finally went to a friend who works on
> them, and asked what to do, as it was always acting up.
>
> He sold me a Mikuni pulse operated fuel pump.  All you need is a vacant
> vacuum port on the carb, and the pulsation works a small diaphragm.
> Marvelous concept, except for the small detail of no port on that Honda.
>
> So, anyway, I got the electric one working.  Hope it doesn't act up out in
> the bush.
>
> Sold the Mikuni to a friend who has a race bike, and he installed it on his,
> and it fixed his fuel starvation caused fluttering.
>
> The thing is elegantly simple.  Three little nipples... vacuum, gas in, gas
> out.  Bolt it on anywhere.
>
> Steve

Those type fuel pumps are very common on many models of ATV's, Riding
mowers and others.

Hank

[cl...@snyder.on.ca]

And built in on many Mikuni and Tillotson regulator carbs. (as well as
Walbro and likely half a dozen other more obscure brands)

[The Daring Dufas]

My 2 stroke .049 model airplane engines from my childhood had removable
heads. ^_^

TDD

[Harry K]

On Apr 2, 6:41 pm, The Daring Dufas <the-daring-du...@stinky.net>
wrote:

> On 4/2/2012 4:10 PM, cl...@snyder.on.ca wrote:
>

> > On Thu, 29 Mar 2012 08:04:35 -0700 (PDT), dennisga...@gmail.com wrote:
>
> >> On Tuesday, March 27, 2012 8:59:03 PM UTC-4, Jules Richardson wrote:
> >>> Pull the head on it and check the bore for damage - typically on these
> >>> smaller engines the head gaskets are quite meaty and will come off clean
> >>> (and can be reused).  Unless, of course, it's a head gasket problem in
> >>> the first place...
>
> >> It's a 2-stroke weedeater. 99.99% chance that it does not have a separate head. The head and cylinder are one piece and bolt to the crankcase. Nearly all small 2-stroke engines have one-piece "jugs."
> >   Stange, NONE of the numerous 2 stroke engines I have floating around
> > have integrated jugs. They ALL have removeable cyl heads.
>
> My 2 stroke .049 model airplane engines from my childhood had removable
> heads. ^_^
>
> TDD

And the simple way to check for bore/piston damage is to pull the
exhausst and take a look.

Harry K

[Steve Barker]

On 4/2/2012 4:10 PM, cl...@snyder.on.ca wrote:

i used to rebuild stihl back pack blowers fairly often. They are all
one piece.
--
Steve Barker
remove the "not" from my address to email

[The Daring Dufas]

Actually, all I had to do was look in the exhaust port to see the
piston. ^_^

TDD

[denni...@gmail.com]

Quick survey of ten chainsaws, three weedeaters, fourteen gasoline model airplane engines, and two snowmobiles: ALL have an integrated cylinder and head (aka jug) that bolts to the crankcase.

Nothing new has a separate head. You either have some very old equipment or you're making it up.