Tuning and running (really) old saws

[av8or3]

Just kinda thinking out loud, maybe share something, hope to learn something.
Most of my old saw experience comes from messing with my old Solo saws made back in the 1960’s. I’ve learned that when tuning them using the fuels and oils available to us now you will have to make changes and tedious adjustments to get them to run as they were intended.
Recently after getting a Solo Twin running for the first time in 20 years and tuning it to really run good I was surprised to find the spark plugs clean as a whistle (white as snow). I was using the recommended mix (25/1) using synthetic oil. It was smoking like I expected while running. I expected some residue as I have another Twin and it’s plugs have a light brown deposit on the electrodes with some color on the insulator.
I thought I’d try the actual mix that was recommended at the time the saw was built just to see if it would leave acceptable deposits on the plugs. What really worried me was that maybe the plugs were so hot that it could lead to detonation and damage to the saw. Anyway, mixed 1/3 pint of non-detergent motor oil with a gallon of e-free 89 octane and poured it in. Once the fuel in the carb burned up the saw would barely run. Smoked like a freight train and would barely run . I tried like heck to adjust it but to no avail. The saw did not like that *s-word. It really pissed me off because it was a long road getting the saw to where it was before I poured that stuff in, now it was going to be a long road back getting that stuff out and retuning it.
I went and looked over the other saw real close and found it was using a colder plug. The saw came with a WK225T1 from the factory and that's what was in the one I just got running with the clean plugs, the one with the “more desirable” deposits was running WK175T1 plugs, a colder plug. Now these plugs are scarce in either form but I was able to score some of the colder plugs to give em a try. It worked. The colder plugs ran cooler in the saw and began to acquire the light brown color I was looking for. It made me feel better about tuning them to their full potential.
This is what I was shooting for, these are the original cold set taken from the saw following a 4 min hard run (on video).

The good news is, as these little spark plugs are very rare now, the colder ones are not so and I was able to score 8 of them. The saws run good and I think it’s reasonable to believe I’ve corrected or improved the situation by running colder plugs in these saws to compensate for the lack of stuff that would leave a deposit like lead and motor oil.
What do you guys think?

 

[drf256]

I think it’s apples and oranges. Neither the fuel or the motor oils are the same as they were back then.

I’d just run 32:1 synthetic 2T oil with e-free fuel and see where you land. Sincerely doubt you’d have any damage. Detonation is unlikely at the compression those old saws ran at.

 

[FergusonTO35]

Totally not what i would expect as far as deposits go, but if it works it works!