3 saws to repair, 2 Stihls & 1 Poulan

[Sub-arctic]

I'm looking to get 3 saws running that I kind of inherited, maintenance-wise anyway. I'm a mechanic, but I haven't messed with small
2 strokes much. I'm looking for some recommendations or pointers on where to get good information on working on these things......... videos, reading material (preferably on-line), or what ever else.

1 saw is a Stihl 025 that I know has had problems for many years. The owner took it to a shop at least a couple of times, it would run okay for a while and then start
having problems again. I tried to use it recently, it seemed to cut okay, but the longer I ran it, the less it would idle.

Another saw is a Stihl 023. I don't know any history on it. I tried to use it recently, I didn't even get it started.

The 3rd saw is a Poulan Pro PP4218AVX. I don't know the history on this one either. I tried to use it as well, it would start and run, but didn't cut worth a darn, and would quit after a few minutes. The chain seemed to be getting very little oil, if any. I did a little file work on the chain, I may not have gotten it very sharp. I will try to check the oil pump and passage ways on this one.
If the chain wasn't getting oil, would it bind up and make the engine quit? The chain didn't seem to be getting bound up.

Hopefully, you guys can point me to some good educational material. I'll start with cleaning the saws up and doing basics that I know I should do, like testing compression, spark, air an fuel filters, and whatever else I can think of, or find out about on my own.

Thanks,
Brett

 

[J D]

Start with compression test, or better yet pull mufflers & check cylinder & piston for scoring. If you use a tester make sure its suitable for small engines (short hose with schrader valve in the end). You need at least 120psi to run but really want +150psi.
Assuming C/P are good they probably all want new lines, fuel filter, carb cleaning out & possibly a carb kit. Sitting with stale/old/bad gas is the cause of an awful lot of issues. After that, if they don't tune & run right you need to be checking for air leaks... older saws often need the crank seals replaced. Clutch side usually goes first. Ideally a pressure/vac test would be done but you can also use a can of carb cleaner or something similar sprayed around the saw while idling to identify leaks

 

[Sub-arctic]

Start with compression test, or better yet pull mufflers & check cylinder & piston for scoring. If you use a tester make sure its suitable for small engines (short hose with schrader valve in the end). You need at least 120psi to run but really want +150psi.
Assuming C/P are good they probably all want new lines, fuel filter, carb cleaning out & possibly a carb kit. Sitting with stale/old/bad gas is the cause of an awful lot of issues. After that, if they don't tune & run right you need to be checking for air leaks... older saws often need the crank seals replaced. Clutch side usually goes first. Ideally a pressure/vac test would be done but you can also use a can of carb cleaner or something similar sprayed around the saw while idling to identify leaks

Thanks for the reply.
I did compression tests, but the only tester I have has an automotive type with an 8" hose that screws into the spark plug hole. A 12" hose plugs into that via a QD fitting. Schrader valve on the aluminum fitting that the gauge screws into. I got 100 on the 025, 110 on the 023, and 125 on the Poulan. I could see one score mark through the spark plug hole on the 025. The spark plug on the 025 was very black with carbon. The spark plug on the 023 was light gray, the spark plug on the Poulan was a darker brown. There was quite a bit of crud on the air filter of the 025. I wouldn't think enough to choke it much if at all, but maybe.
I cleaned out the oil passage on the Poulan with a piece of wire. I haven't figured out for sure where the oil pump is, but I'm guessing I have to remove the clutch and dig deeper to get to that. I might try running it again since I cleaned the passage.
That was as far as I got tonight.
I thought about old gas after I initially posted. That might explain some of the problems now, but at one time the 025 was used fairly regularly, and I think it always had problems.

 

[J D]

If you can do a compression test on a known good saw of a similar size that will give you an idea of what your tester should read on a saw that should run.
At this point in time I'd probably focus on the Poulan as that seems likely to be the most straightforward. I wouldn't go poking wire down the oil lines, that's more likely to do harm than good. Remove the pump & check the drive gear, blow air through the passages, clean the oil tank out with kero or diesel, & clean or replace the oil pickup strainer. The pumps are a pretty simple piston design but it doesn't take much to restrict the flow. More often than not it's just crud built up in the bar rail or blocking the oiler hole in the bar. Check the bar is correct for the saw too.
Personally I'd worry about the fuel side of things & getting the saw running properly (carb cleaned/kitted, fuel lines, filter, etc) before I got too involved in fixing the oiling

 

[Michael E]

Stihl 023 and 025 are basically the same saw, just with different displacement. Most parts should be interchangeable. That gives you the opportunity to exchange carburator, coil, etc. and see if that fixes the problem. I still recommend an systematical approach. Your two stroke engine needs fuel, spark, compression and impulse. Check those systematically.

I would also recommend to take off the exhaust first. If there is a spark arrestor, it may be plugged. A look into the engine will tell you a lot about the condition of piston and cylinder.

The Poulan is not worth a lot of money. From the economic side, it makes no sense to put a lot of time and money into it. It's still fun, though.

 

[Sub-arctic]

Stihl 023 and 025 are basically the same saw, just with different displacement. Most parts should be interchangeable. That gives you the opportunity to exchange carburator, coil, etc. and see if that fixes the problem. I still recommend an systematical approach. Your two stroke engine needs fuel, spark, compression and impulse. Check those systematically.

I would also recommend to take off the exhaust first. If there is a spark arrestor, it may be plugged. A look into the engine will tell you a lot about the condition of piston and cylinder.

The Poulan is not worth a lot of money. From the economic side, it makes no sense to put a lot of time and money into it. It's still fun, though.

I read that the 023 and 025 were built on the same chassis(?), and had thought a little about exchanging parts. I hadn't gotten too far on that thought yet though, I'm glad you suggested it. I did test the 023 for spark, and it looked like it was working pretty well to me. The air filter looked pretty clean, so it would seem to be a fuel problem. Last night I started trying to find out if it has a fuel pump. I'm guessing it does, maybe a diaphragm type? I hadn't found an answer yet. I supposed the carb could be gummed up with bad gas too. I have no idea how long it's been since it ran.
I had to look up impulse, I was not familiar with that term relating to engines. I infer from that, that it does have a diaphragm type fuel pump that runs off of impulse? I am familiar with those type of pumps.
I will remove the exhausts soon, and inspect what I can.
I've read that the Poulan is not a very good quality saw, but it has the best compression of the 3. I will put some time into it, if nothing else I will probably learn something from it.

 

[Sub-arctic]

If you can do a compression test on a known good saw of a similar size that will give you an idea of what your tester should read on a saw that should run.
At this point in time I'd probably focus on the Poulan as that seems likely to be the most straightforward. I wouldn't go poking wire down the oil lines, that's more likely to do harm than good. Remove the pump & check the drive gear, blow air through the passages, clean the oil tank out with kero or diesel, & clean or replace the oil pickup strainer. The pumps are a pretty simple piston design but it doesn't take much to restrict the flow. More often than not it's just crud built up in the bar rail or blocking the oiler hole in the bar. Check the bar is correct for the saw too.
Personally I'd worry about the fuel side of things & getting the saw running properly (carb cleaned/kitted, fuel lines, filter, etc) before I got too involved in fixing the oiling

I haven't found out for sure how to get to the oil pump. Do I need to remove the clutch?
Your point about getting the saw running right before worrying about oiling is a good one, but if I can test the oil pump early on, I would like to. If it's a diaphragm type, I would think I should be able to test it by blowing / sucking on the ports. I don't know what the availability of parts is around here, if I have to order parts, I might want to order everything at once.

 

[Sub-arctic]

If you can do a compression test on a known good saw of a similar size that will give you an idea of what your tester should read on a saw that should run.
At this point in time I'd probably focus on the Poulan as that seems likely to be the most straightforward. I wouldn't go poking wire down the oil lines, that's more likely to do harm than good. Remove the pump & check the drive gear, blow air through the passages, clean the oil tank out with kero or diesel, & clean or replace the oil pickup strainer. The pumps are a pretty simple piston design but it doesn't take much to restrict the flow. More often than not it's just crud built up in the bar rail or blocking the oiler hole in the bar. Check the bar is correct for the saw too.
Personally I'd worry about the fuel side of things & getting the saw running properly (carb cleaned/kitted, fuel lines, filter, etc) before I got too involved in fixing the oiling

I found another thread on this site that gave a description of how the oil pump works, and where it is, so I'm good on that. It also gave some other good information, such as priming the oil system.
I think I've got enough information to keep things going for now.