What did I do wrong?

[Hammermechanicman]

The difference between 150 and 105 is too much to just be wet vs dry ring. Those poulans just don't seem to be as robust as saws like stihls with nikasil plated cylinders. The 34cc poulans have thinly chrome plated pistons and bare aluminum cylinders (cheaper) that do not tolerate running lean for more than a few seconds as opposed to nikasil cylinders that can tolerate lean running longer before scoring.

 

[StarTech]

This is an air head setup and some require an extra rich high side carburetor (as much as 3 turns out from seated) so yes it is possible has sever cylinder damage from running way too lean. Pull the muffler and check the exhaust side of the piston for damage. 105 psi is right at the bare minimum for any two cycle normally to even hit on fuel mix.

Luckily the PNC is only about 33-35 usd plus shc or about 22 usd plus shc if you go through a distributor. Really cheap compared to what they were in the past. Plus as said they are cheap for a reason; no plating.

 

[Hammermechanicman]

I don't know if this is a strato saw or not. If it is Star is right about setting the mixture. These cockroach saws are clamshell crankcase design so swapping out a P&C kit would cost a customer more than a new saw. None of the dealers and big shops around me won't even work on them. I have a guy who flips stuff he finds on the side of the road or garage sales. He brings me about a half dozen of these saws a year. Most go in the traah. If i can fix them with just fuel lines and a carb clean he has me fix it and he then sells it for $20 more than i charged. I think he just like doing it because he isn't making much money.

If you work on these things and the customer complains about it crapping bar oil everywhere when it is stored tell them to let the saw cool and then open the oil reservoir cap then replace and it MIGHT not crap so much oil while stored and drain all the fuel out or be prepared to remove the fuel cap with pliers and then when it won't start replace the fuel lines.

 

[StarTech]

Well I am 99% sure it is a Strato setup. Item 11 is the air head and item 12 is the carburetor.

 

[Hammermechanicman]

Yup, strato.

 

[StarTech]

Also this saw sold for $300 +- pending where you brought it. It is now a discontinued unit.

 

[PTmowerMech]

I remember from a video Steve did, he said not allowing a chainsaw to warm up can cause the cylinder to score and rings can get stuck. something to do with the piston expanding faster than the cylinder.

It had warmed up, because idled for a couple of minutes prior to finding the H adjustment that allowed WOT. Unless a couple of minutes isn't long enough. It took a little bit to find that spot. Many moments it would sit and idle while I was thinking.
Steve has a couple of good video's about how to tune a two cycle.

 

[PTmowerMech]

My thought was the difference between a wet compression and a dry compression. If the first compression reading was done with fuel/oil in the rings could give a higher compression reading but after running and drying out the rings will be lower since they don't seal as well.

I always pour a tiny bit of mix into the cylinder before i do a compression test. IIRC, it was something I learned on this forum, and it just stuck in my head. And check compression at least 3 times.

 

[StarTech]

I would investigate the PNC for damage as compression number now is too close to failure level. It easy enough to pull the muffler. The damage may have already been there to start with.