Still seeking help on old poulan chain saw

wilburn cox

Well-Known Member
Joined
Feb 24, 2014
Threads
40
Messages
107
I posted an earlier thread about problem sith my old poulan chain saw. The model is S25. I received several responses and appreciate each one. On my earlier thread titled Need Help With Old Poulan chain saw i listed all the thing I have done to the saw and all parts which I have replaced.
I had some time this morning so I went to the shop took the spark plug out and tried the pull rope. The engined pulled very easily and with no resistance completely through the pull. I replaced the plug, LEFT OFF THE PLUG WIRE and tried to pull the rope. It felt like the engine had 300 pounds of compression. By jerking hard on the starter rope it will move only a few inches. I do not understand this at all.
I have my original owners manual for the saw but it isn't much help. Does anyone know where I might find a complete repair manual for the saw?

All help and suggestions will be greatly appreciated.

Frustrated Texan and yes we all still need rain.
 

tomsteve

Member
Joined
Jan 31, 2014
Threads
1
Messages
46
I posted an earlier thread about problem sith my old poulan chain saw. The model is S25. I received several responses and appreciate each one. On my earlier thread titled Need Help With Old Poulan chain saw i listed all the thing I have done to the saw and all parts which I have replaced.
I had some time this morning so I went to the shop took the spark plug out and tried the pull rope. The engined pulled very easily and with no resistance completely through the pull. I replaced the plug, LEFT OFF THE PLUG WIRE and tried to pull the rope. It felt like the engine had 300 pounds of compression. By jerking hard on the starter rope it will move only a few inches. I do not understand this at all.
I have my original owners manual for the saw but it isn't much help. Does anyone know where I might find a complete repair manual for the saw?

All help and suggestions will be greatly appreciated.

Frustrated Texan and yes we all still need rain.


you got the right plug in it? piston hitting the plug?
 

Mikel1

Well-Known Member
Joined
Jul 21, 2013
Threads
10
Messages
897
If you place your thumb over the spark plug hole then slowly pull the rope. Is it still hard to pull? Is flywheel binding on coil or cover?
 

motoman

Lawn Addict
Joined
Aug 11, 2011
Threads
67
Messages
2,582
Wilburn, A long shot. If the saw is old it probably has transfer ports cast in the crankcase. Are they somehow blocked? If yes, then the empty spark plug hole gives the only relief to compression. With plug in you are forcing air past the piston rings which is difficult. Wrong piston fitted without cutouts on skirts?Someone chime in here.:anyone:


I wish we could share some rain. 52 inches since Sept, 12 inches this month
 

wilburn cox

Well-Known Member
Joined
Feb 24, 2014
Threads
40
Messages
107
If you place your thumb over the spark plug hole then slowly pull the rope. Is it still hard to pull? Is flywheel binding on coil or cover?
Thanks Mike;
Yes, if I place my thumb over the plug hole the starter will pull but I can feel a lot of pressure on my thumb. No, the flywheel is not binding anywhere.

Thanks for your question and offer of support,
Red Cox
 

wilburn cox

Well-Known Member
Joined
Feb 24, 2014
Threads
40
Messages
107
Wilburn, A long shot. If the saw is old it probably has transfer ports cast in the crankcase. Are they somehow blocked? If yes, then the empty spark plug hole gives the only relief to compression. With plug in you are forcing air past the piston rings which is difficult. Wrong piston fitted without cutouts on skirts?Someone chime in here.:anyone:


I wish we could share some rain. 52 inches since Sept, 12 inches this month

Thanks Motoman; The saw is old. I won it in a sales contest in about 1978/1980. One reason I like the saw is that it is all metal, no plastic like my newer saws. I have had the saw completely disassembled but I am not familiar with transfer ports in the crankcase. Are these ports small holes such as with carbs??
As for the piston..and cut outs on the skirts. I could not find a NEW PISTON AND CYLINDER FOR THE SAW so I ordered a used set from a place called "Chain sawr". The piston and cylinder was an exact match for the original ones in the saw.
Your are correct, the EMPTY spark plug hole allows the pull starter to move the piston and everything freely without any hesitation. With the plug installed and plug wire off then the starter is extremely difficult to pull and it feels like the whole crankcase is full of air. I took the muffler off this morning and with the plug installed I don't think any air was coming through the exhaust port.
You could be right about transfer ports but I, being honest would not know what to look for if I dismantle the engine again. Any help appreciated.

Here is what I did to the saw last year and then just placed it on the shelf while getting busy with other things.

Completely dismantled the saw BUT did not remove the piston rod from the crank shaft. Carefully cleaned all parts of saw.
New parts installed,
1. New chain sprocket
2. Soaked carb. and installed new carb kit and all gaskets
3. USED PISTON AND CYLINDER ordered from "Chainsawr" these were in great shape, clean and matched original ones in saw , installed new rings
4. Replaced all gaskets including cylinder and crankcase
5. Disassembled gas tank, cleaned and added new gasket, fuel line and new filter inside tank
6. New dust shield and air filter
7. New flywheel key
8. New oil cap on on bar oil tank
9. New pull starter pulley and rope.
10. I DID NOT DISASSEMBLE THE DIAPHRAGM OIL PUMP supplying oil to the bar and chain.

I have three mowers. a Kubota tractor and several pieces of equipment which I repair, rebuild and keep running bur I have never had a problem like this. That's why I am determined to get this little saw back in good condition. My wife says it's a "Man thing"

thanks for any help

Red Cox
 

wilburn cox

Well-Known Member
Joined
Feb 24, 2014
Threads
40
Messages
107
you got the right plug in it? piston hitting the plug?

Thanks tomsteve; yes the plug is correct and there is no indication the piston is hitting the plug no odd sound and no bent tip on end of plug.

Thanks for your input; Greatly appreciated

Red Cox
 

Fish

Lawn Pro
Joined
Aug 2, 2013
Threads
11
Messages
5,145
What about the cylinder gasket? Were they identical as well? Did you make one? Just use sealant?
 

wilburn cox

Well-Known Member
Joined
Feb 24, 2014
Threads
40
Messages
107
What about the cylinder gasket? Were they identical as well? Did you make one? Just use sealant?

Thanks Fish. The cylinder gasket was a new one. I did not use sealant. The original cylinder gasket on the saw was stuck and when I removed the cylinder it messed up the old gasket. I could not compare it to the new one.

Thanks again for you response.
 

Fish

Lawn Pro
Joined
Aug 2, 2013
Threads
11
Messages
5,145
Like I said earlier, you either have excess fluid hydro-locking the piston, or something has changed the ratio in some way, like excess carbon, different stroke or different piston, or closer fit of the cylinder to crankcase that would change the ratio. there were many models that were real close to this one, maybe you have a slightly different crank/piston, etc...

Check out those threads I sent you in the p.m., there are some serious poulan nuts there that could probably help, they love those old Poulans.
 
Top