Poulan 335 Pro Help

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Anne_A

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Hello all, I'm new here and am in need of some help. Recently I acquired an "older" Poulan 335 Pro (20inch bar). It has been very stubborn about starting and when it actually was starting it would lose power at full throttle, stall and die. It was also idling very unevenly but that was somewhat fixed by running carb cleaner and adjusting the L mixture screw. I was able to get it to run slightly better at high speed by adjusting the H screw on the carb but the problem still persisted and seemed to get worse the more I ran it. I assumed this was a carburetor issue based on the way it was bogging down and stalling so I decided to rebuild the carb and replace the fuel lines while I had the saw apart. The fuel lines were very brittle and starting to crack so they were definitely in need of replacing. I also changed out the spark plug since the plug it came with was dirty and beginning to foul.

Since rebuilding and cleaning the carburetor the saw has been even more stubborn about starting and will not run for more than about 15 seconds if it starts at all. The carb is a walbro HDA-49 and was rebuilt using the kit specifically for the HDA carbs (part number K22HDA).

I have now cleaned the air filter, rebuilt/cleaned the carb, cleaned the exhaust screen located in the muffler, replaced the fuel lines, and replaced the spark plug but I am still having trouble.

After rebuilding the carb I set both the L and H adjustment screws to 2 full turns (360 degrees) out from all the way in. I've made adjustments to both screws in 1/4 turn increments and have seen little affect on the saws performance. The saw seems to be firing a little better when the H adjustment is set close to 3 full turns out and the L screw is set to a little less than 2 turns out. The idle adjustment screw doesn't seem to help keep the engine running with adjustments in either direction.

I have not checked compression with an actual gauge but have tried to plug the spark plug hole while pulling the starter cord and am unable to keep it sealed with my thumb when I pull the starter cord at a normal starting rate. If I pull extremely slowly I can mostly keep the hole sealed off. I know this doesn't give us any real numbers to go off of but I believe it does tell me that compression has not been lost completely.

I have checked that the piston does in fact move when the starter cord is pulled. When the spark plug is removed it's very easy to see the piston moving up and down when the cord is pulled.

At this point I'm not sure what else to do besides start checking the actual engine (cylinder, piston, crankcase, etc.). However from my limited experience with other 2 stroke engines this seems more like an issue with the carburetor than anything else.

Does anyone have any suggestions on what else I could try? Any help would be appreciated.

Oh and I did change out the gas when I first got it. It's running regular unleaded gas with 2-cycle oil mixed at a 40:1 ratio.
 
It does sound like the saw may indeed have some engine damage. As suggested above pull the muffler off and have a look inside. If everything looks good this video may help you get the carb dialed in

At this point if turning L needle has little effect, especially if turning the needle out doesn't lower the rpm's the saw then likely has an air leak, and will require a vacuum/pressure test.

Sent from my HTC One_M8 using Tapatalk
 
One thing reading this that I didnt see replaced and is a must on these. Impulse line running from back of cylinder crankcase to top of carb.

It cracks and gets brittle too. I had one fall off where it was cracked on a new to me saw that just came in.

If you are trying to run one without this or cracked you will score that piston. Lean

3mmx6mm echo fuel line or even 3mmx5mm echo line. Have used tygon in the 3mmx6mm in past and lasted 10 years, but the echo line is better. Also tygon can be used in a pinch as it is so easy to replace with long forceps. Till you test and get better replacement later.
 
Well I pulled the muffler off and took a look inside the cylinder and found that the piston and cylinder had indeed been scored (picture included). Looks like I'll be replacing them.

Jeremiah - I did replace the impulse line, just forgot to include it in the original post. Thanks!

This photo was taken with the piston up but the sides of the cylinder look the same.
335%20PistonCylinder_zps9iaxnd9n.jpg
 
This will draw righteous scorn from purists, but for a light use saw, I have had great success with cleaning such a cylinder and piston with abrasive paper and installing nothing more than a new ring. At least you could get it going that way to check out the rest of the saw before investing in expensive parts. Depends on how you plan to use it, how you value your time and how much you love the saw. Then you can figure out what caused it to fail in the first place. Maybe you have already fixed it with your carb work. Don
 
Thank you all for the help. I removed the cylinder and piston this morning and found that the ring on the piston had actually broken and was causing some of the scoring. I have now ordered the suggested piston kit and will install it next weekend.

What do you guys recommend using for a sealant around the base of the cylinder?
 
Thank you all for the help. I removed the cylinder and piston this morning and found that the ring on the piston had actually broken and was causing some of the scoring. I have now ordered the suggested piston kit and will install it next weekend.

What do you guys recommend using for a sealant around the base of the cylinder?
Yamabond 4. Where did you order your parts from? thanks.
 
If using gasket I have never used a sealant on these.

Did you buy new? Did you make sure your saw had the 335 cylinder on it? Piston 46.5mm would have had 2 thin rings if oem 335
Unless someone already put the 330 3450 piston in it. Still check bore for 46.5mm

Gasket kit is like $7 I would order one for all the gaskets for future use anyways.
 
If using gasket I have never used a sealant on these.

Did you buy new? Did you make sure your saw had the 335 cylinder on it? Piston 46.5mm would have had 2 thin rings if oem 335
Unless someone already put the 330 3450 piston in it. Still check bore for 46.5mm

Gasket kit is like $7 I would order one for all the gaskets for future use anyways.

I bought the saw used for about $50 which included the saw, 3 brand new chains, and a blade guard. I will double check the bore size this evening and order gaskets as well based on your suggestion and others' remarks regarding gaskets vs. sealants.
 

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