Need help with old Poulan chain saw

[wilburn cox]

I have a Poulan 16" chain saw won in a sales contest in 1977. Yes, I know it's old. I have a Stihl pole saw and a Stihl 18" saw and love them. This little Poulan was great for limbing until I placed it in a shop for tune up.
The little saw is in or (was) perfect shape, kept in the case when not in use and properly cleaned and stored after use. After being in the shop it was very hard to start. Pull ripe would almost break my wrist. I set it aside until I had time to go through it myself.
I tore it down, ordered and used piston and cylinder (could not locate a new one). The Piston and cylinder was in great shape. I installed new rings, rebuilt the carb, new plug and etc. All back together and it did not correct the problem. Without plug installed the pull rope is easy. With plug installed it almost takes two men to pull the starter rope. After jerking extremely hard for several pulls it will start but I know something is wrong. It feels like it is firing at the wrong time. I replaced the flywheel key but it did not change.
Could my problem be in coil?? yes, I know I have spent more than the saw is worth but I'm a hard headed Texan. I repair all my mowers, tractor and the Stihl saws. I enjoy working and learning but now I'm frustrated.
Any suggestions will be appreciated. I love the forums.

Frustrated Texan

 

[lzn197]

You stated "after being in a shop". What was it in the shop for??? What problems/symptoms ETC?

 

[davbell22602]

Can you turn the flywheel by hand easy or is it hard to turn? If it turns easy check and clean your recoil starter by taking it apart.

 

[wilburn cox]

You stated "after being in a shop". What was it in the shop for??? What problems/symptoms ETC?

A friend borrowed the saw and when he returned it the thing looked like he had carried it in the back of his truck for a month and not inside the case. We had just bought 4 acres to build our retirement home on. Needed to trim some trees so put it in the shop for complete going over. Ran for awhile and then the hard to pull situation began.???

 

[wilburn cox]

Can you turn the flywheel by hand easy or is it hard to turn? If it turns easy check and clean your recoil starter by taking it apart.

With recoil starter off the saw and the plug installed I can turn the flywheel just a little and then it kicks back like it is firing at the wrong time or something. I have completely dismantled the saw. Replaced the cylinder, piston and installed new rings. The old cylinder and piston was not scored or damaged that I could determine.
The coil does produce fire but I am wondering why it feels like the it is firing at the wrong time. I have newer encountered anything like this before. The Pull starter is fine and is not dragging against anything. When pulling on the rope the flywheel kicks back hard. It will jerk the rope out of my hand.

 

[davbell22602]

Crank bearings are probably half froze up and need replaced. Also check for dirt and debris on clutch side around the clutch and sprocket also.

 

[wilburn cox]

Crank bearings are probably half froze up and need replaced. Also check for dirt and debris on clutch side around the clutch and sprocket also.

Thanks,davbell; Crank bearings are fine. I have been through every part of the saw. All is clean. No debris. Check all wires and no short is evident. Is it possible for the coil to be bad even though there is spark? I have one of those spark testers and the spark jumps inside the glass apparatus. With the spark plug OUT the pull rope spins the motor very easily. With plug installed the pull rope won't move the flywheel inches, and that is with a very hard jerk on the rope. It kicks back. The saw will start after many very hard pulls and the saw will run eventually. I have been working with it only in my shop, not cutting wood. I know I will have to fine tune the carb but that is useless unless I can figure out the hard pull. I have had several saws in the past and every one will start after a few pulls on the starter. On this saw when I pull the rope it will only pull a matter of INCHES and kicks back like a MULE.. Like the flywheel is kicking backward. Does not make sense..
The saw is Poulan Model # S-25CVA-38CCM. Here is what I have done to the saw; New chain sprocket. New carb. kit. Replaced cylinder, piston and new rings. Replaced all gaskets including crankcase gasket. Disassembled gas tank, cleaned and added new gasket, fuel line and new filter inside fuel tank. Replaced dust seal and air filter. installed new flywheel key. Installed new oil cap assembly on bar oil tank. Installed new pull starter pulley with new rope.
The carb. has a reed below the carb body ans saw. This reed did not look damaged and was very flat and clean so I did not replace it.
As I stated in my original post, I have spent a lot of money on an old saw but I am determined to make it run. I have always been able to repair my own equipment and was born on a small farm 73 years ago. Like many of our generation we had to make do with what we had. Taught to respect what we were blessed to have and keep on keeping on. My little wife says she only remembers one thing I could not repair and that was on electric can opener. Oh well..
Thanks for letting me bend your ear.

Frustrated Texan

 

[Fish]

There are a few things that could cause this, one is a large buildup of carbon on top of the piston and the combustion chamber,
but if you swapped the piston, it is assumed that you decarboned things.

Another possibility is that the oiler is letting bar oil into the crankcase.

Another, is that the carb is flooding a tad.

 

[wilburn cox]

There are a few things that could cause this, one is a large buildup of carbon on top of the piston and the combustion chamber,
but if you swapped the piston, it is assumed that you decarboned things.

Another possibility is that the oiler is letting bar oil into the crankcase.

Another, is that the carb is flooding a tad.

Thanks, Fish; Piston and combustion chamber are spotless. I'm not sure how the oiler could let bar oil into the crankcase. It is possible the carb could be flooding because when I CAN finally get it started it drinks a lot of gas. could the carb flooding cause the extreme amount of kick back on the pull starter?

Thanks for your input. I must say that I appreciate the quick responses I have received from several on the forum. This helps a lot

Frustrated but trying,

Now I have some electric fence to repair...

 

[Fish]

Yeah, I don't think you gave us a model number, so I don't have a clue what oiler setup you have just a guess going by the age and description. Most of those used a little diaphragm oiler that was pumped by the impulse of the crankcase, and if the diaphragm would crack, it would let bar oil suck into the crankcase and eventually into the combustion chamber.

the same scenario would occur if the carb was flooding, it would "hydro-lock", as the engine cannot compress a fluid.

to find out drain both the gas and oil tanks and thoroughly rinse with fuel mix. Drain for a day or two upside down, filler plugs and spark plug out/off/gone, and periodically pull the rope a bunch of times to thoroughly dry it out, do not have the plug
attached to the plug wire, or you could have a green flamethrower. After you are convinced that the system is totally dry,
reinstall the plug and pull it like you were going to start, with no gas or oil in it, and see if it pulls a lot better.

If it does, then add fuel mix only to the gas tank and try to start, off course leave the bar and chain off.