Poulan 5200 RPM too high at wot

[Evil XL 12]

I finally managed to find a Poulan 5200 a couple of weeks ago. The saw is in excellent condition. The saw ran but would bog down at full throttle. I replaced the fuel line and filter and rebuilt the carburetor. I've rebuilt dozens of carburetors but I screwed up on this one. I went to replace one of the welch plugs and it turned out to be a brass check valve. I destroyed it. I was a bit horrified because the part is made of unobtanium but I did manage to find one on ebay. I installed it and properly aligned it. After I got everything back together I turned the carburetor to idle properly and adjusted the high jet as well. The saw will run great at wot initially but after a few seconds it starts to rev way too high. I'm not sure if it's an air leak or something with the check valve or what. Do any of you have any advice or ideas? I don't use a tachometer to adjust my saws and I would really hate to burn up such a fine saw.

 

[Modifiedmark]

Hard to diagnose a saw over the internet, especially after someone already worked on it. No offense.

What I can tell you is that if that saw is right, both the high and low screws will be almost exactly one turn out from closed. If either one varies more the 1/8-1/4 turn you got other problems to deal with.

The carb on a 5200 has a brass fuel governor in them. They can malfunction but when they do they most the time cause them to run real rich. Your saw will need to be tuned in the cut to make the proper high speed adjustment because of that fuel governor.

I never mess around with fine old saws like that, I change the seals almost immediately. They are too easy and too inexpensive to gamble on almost 50 year old rubber seals. Also while you had the carb out, did you check the gaskets and reed valves?



Did you get the button on the metering diaphragm hooked in the lever right?

If you have done lots of carbs and think you got it right, just change the seals and check for gasket leaks. Even if they are not the problem now they won't be in the near future either if you change them.

I have always used National 471466 seals on mine, but they are a bit tight. Fossil has found Dichtomatic 17X28.5X6TC-BX are a better fit

 

[Evil XL 12]

I finally managed to find a Poulan 5200 a couple of weeks ago. The saw is in excellent condition. The saw ran but would bog down at full throttle. I replaced the fuel line and filter and rebuilt the carburetor. I've rebuilt dozens of carburetors but I screwed up on this one. I went to replace one of the welch plugs and it turned out to be a brass check valve. I destroyed it. I was a bit horrified because the part is made of unobtanium but I did manage to find one on ebay. I installed it and properly aligned it. After I got everything back together I turned the carburetor to idle properly and adjusted the high jet as well. The saw will run great at wot initially but after a few seconds it starts to rev way too high. I'm not sure if it's an air leak or something with the check valve or what. Do any of you have any advice or ideas? I don't use a tachometer to adjust my saws and I would really hate to burn up such a fine saw. View attachment 971878View attachment 971879

Hard to diagnose a saw over the internet, especially after someone already worked on it. No offense.

What I can tell you is that if that saw is right, both the high and low screws will be almost exactly one turn out from closed. If either one varies more the 1/8-1/4 turn you got other problems to deal with.

The carb on a 5200 has a brass fuel governor in them. They can malfunction but when they do they most the time cause them to run real rich. Your saw will need to be tuned in the cut to make the proper high speed adjustment because of that fuel governor.

I never mess around with fine old saws like that, I change the seals almost immediately. They are too easy and too inexpensive to gamble on almost 50 year old rubber seals. Also while you had the carb out, did you check the gaskets and reed valves?



Did you get the button on the metering diaphragm hooked in the lever right?

If you have done lots of carbs and think you got it right, just change the seals and check for gasket leaks. Even if they are not the problem now they won't be in the near future either if you change them.

I have always used National 471466 seals on mine, but they are a bit tight. Fossil has found Dichtomatic 17X28.5X6TC-BX are a better fit

I wasn't asking for a diagnosis, just ideas and you gave me some really good ones. Thank you for the information, especially the part numbers. I went out to mess with it more after supper last night and I found the problem. I had an air leak where the carburetor mounts up. The little plastic block that it mounts to right above the reed valves had a small crack. I had another so I installed that one and it runs great now. I have the high adjustment sitting at 1 1/2 turns out and the low is 1 1/8. I turned the saw on each side while running to see if maybe the seals are leaking and there was no change in the idle speed. This saw actually looks really clean internally. There wasn't even saw dust or oil in it anywhere when I pulled the top cover and clutch cover off. I haven't tested the compression with a gauge yet but it's enough that I wish it had a decomp button. Thanks for the part numbers and the advice. I was cutting some maple logs with it to adjust the high when I noticed the excessive RPMs yesterday. The saw went from normal speed at WOT to cutting through a 14 inch maple log in about 1 second. Definitely not cool. I will cut with it again today to fine tune it. I'm really impressed with the power of the saw. I think it can beat my Homelite 550. I'm eager to see which one cuts faster.

 

[Modifiedmark]

If you have to have the saw at 1 1/2 turns out on the H screw you still have a issue and its compensating for a small air leak. Turning the saw on its side is not a surefire way to check for a leak, especially a small steady leak that your compensating with a abnormal carb adjustment.

When I said check the reeds and gaskets under the carb mount that kind of includes finding a crack in that area..