Normal Compression # for a Craftsman/Poulan Saw? And Advice

[Seakaye12]

Well....this saw was given to me and I initially felt that the compression; judged by pulling the rope.....was extremely low. I looked through the exhaust port and things looked "OK".....so I injected some PBlaster into the cylinder and let it soak for a day or so.

Today I tried starting the saw and could get it to fire and rev...but would repeatedly fail to idle and would stall.

Still thinking compression was the problem I tested it and was surprised to see 115 PSI.

Is that normal? It still feels sooooo weak when pulling the rope.

Assuming the compression is in fact adequate.....could someone review the carb adjustments for me? I have been told that the L screw actually controls power and acceleration; and the "H" screw will adjust idle quality? Really?

Any information or suggestions would be helpful. It's a ZAMA C1M W26C 75A carb. The model of the saw is Sears 358.351810

Thanks, Chuck

[RoyM]

That is a good compression reading, the rewind is obviously designed to reduce starting effort. H is the high speed mixture screw, if the limiters are gone turn ccw until the the saw refuses to rev then turn the other way in increments until it 'four strokes', that is, it starts to hunt up and down. If it has limiter caps, likely unless someone removed them, turn ccw as far as it will go. L is the idle mix, it should be rich enough to allow the saw to pick up speed cleanly

[KE4AVB]

Agree with RoyM. On those saws even on a newly rebuild the compression will be only 125-145 cold psi depending on which cylinder/piston combination was used.

Not idling can be a sign the carburetor is just needing rebuilding if the L adjustment doesn't correct it. Metering diaphragm stiffens over time causing carburetor to have less fuel available at idle. These carburetors are fairly inexpensive online and includes the primer. Depending on your skill level and time involved it might be more cost effective to go with a new carburetor as rebuilds can cost as much as the new carburetor.

[Seakaye12]

Yes it's interesting how cheap the ZAMA carbs can be on e-bay; especially through some of the Chinese vendors. There's one who sells the carb AND the primer AND THE SPLINE TOOL! for $9.99 WITH FREE SHIPPING. Sheesh.

I have to admit; I'd really like to have that tool. The needles are sooooo tiny (0.17 at the splines) that I don't dare try to cut slots into them...and they are VERY tight; makes adjustment with any of the DIY methods (electrical connectors and the like...) very difficult. They just slip on the splines.

I managed to make an extension with fuel line and a stove bolt.....but the needles are so close together that I can only slide the extension on one at a time. A royal pain; this one is one of the most frustrating renditions of the EPA restrictions that I have seen.

Tempted to just order the carb with the tool. Anyone here deal with this vendor? wangluo18

[KE4AVB]

Not myself. He also has the same carburetor deal listed for $16.89.

As the tool wait until you run into one of those round with a pin hole version. I have heard of them but so far I have only needed the spline, single D and the pac-man versions.

[Seakaye12]

The $16.89 offer is a "Buy It Now". $9.99 is a starting bid but in looking through the sales history I saw at least one sale made at the $9.99 price.

[Arkie]

If it starts and revs up it should idle if all else is ok even with low compression. Low compresssion would make it little weak in the cut, I have one of those saws that compression is lower than yours and it starts runs and cuts good, but I had to do the carb kit and fuel line tune up to get it their. (I removed the limiters and took a dremel to the jets and cut a slit for a small screwdriver but I had more metal to work with than yours and the jets turned easily with the screwdriver. The low speed jet on mine also affected the initial rev up of the high speed. If the low was adjusted for best idle the saw would bog when throttled for high and had to carefully adjust the low jet for good fast acceleration and it was critical like 1/4 turn after saw got warmed up to not bog when first accelerated. (this jet adjustment is sometimes mentioned in their owners manual but warns to not remove the limiters due to YOU then being responsible for GLOBAL WARMING and a fed offense.

I would try for the carb and tool and get new tygon gas lines of the ethanol type, but don't use or test with ethanol gas and if that don't correct the idle issue I would vacuum and pressure test the powerhead. Also note that them saws are for OCCASIONAL USE ONLY. (lots of plastic pieces) but good light weight trimmer type saws.
Install a new spark plug of correct type.

[dougand3]

I've bought lots of parts from wangluo18. They are very reliable but shipping takes 10-18 days.

[JonCraig]

I've also bought from him twice, I believe. Parts were exactly as described. However, if I recall correctly, they were just two carb kits. I've never purchased something as complicated as a full carb.

--JC