Modified saws gas/oil mixture

[woodworkingboy]

I run a number of woods modded saws, and have always pretty much used high octane gas at a 35:1 ratio, thinking that the increased oil would be good for the engine running at the higher than stock rpms, and higher compression. I recall Brian (Timberwolf) having that recommendation as well. Some saws in particular seem to run better at 50:1. I just switched over to 50:1 yesterday, and haven't had time to notice if there is also the tendency to run hotter now too. I'm wondering what folks are using in their modded saws, and by modded, I mean beyond just a muffler mod? I don't like to tune them down with a richer setting at the carb, but perhaps sacrificing some performance with a more oil mix is a good thing? Thanks.

 

[SkwerI]

I mix my fuel at 50-1 but I use premium gas and a premium synthetic mix oil. If it's crappy gas or cheap oil, then more isn't going to help much. Using the best oil I can means I don't have to use extra to compensate for its shortcomings.

 

[Al Smith]

As I've said before I run all the two cycle stuff on hi-test and 32 to 1 ratio .Just my preference ,nothing else .

 

[woodworkingboy]

I believe it to be a somewhat controversial point, but my impression is that the greater oil, though perhaps a positive with it's higher lubrication factor, it also can add an element of interference to the combustion, or whatever exactly the mechanism is where there is a decrease in performance. With my 242xp that is fully modded, I also slapped a larger carb on it, so it is getting more gas than with the stock carb. With the 35:1 mix, it still runs too rich with the high speed adjustment closed all the way, and will smoke. With the 50:1 ratio at the same setting, it seems to be right where I want it and definitely runs at a higher rpm, nudging on 16,000. It tells me that the lesser oil is providing a better balance and giving more power to the engine. The 020 also runs better, turns a good limbing saw into a great limbing saw.

 

[CurSedVoyce]

40 - 45:1 here. The modded 046 seems to like that range well. I use 40:1 in the higher heat days and 45:1 below 100 F. I use the full synthetic Stihl and high octane

 

[Tucker943]

More oil does nothing but slow the burn and dirty the exhaust port. Crud in the exhaust port will cause scoring in the cylinder. Use enough oil to do the job and no more.

 

[woodworkingboy]

"More oil" is a vague term. Remember, talking here about a level of performance and demands on the engine beyond the stock parameters.

It's an interesting point. I recall when I was reading up on it, that some test bench examinations with oil mixes and different types of oil, possibly showed that an increase in power resulted from some oils (the synthetics, I believe). I'm talking about the combustion factor, not something resulting merely from lubrication. I also seem to recall that Timberwolf may also have prescribed to that theory, or at least elicited some of the findings. It seemed controversial, as I already mentioned, and more complete studies were required. The point is that with the oil, there are other things going on besides just lubrication, either enhancing or detracting from performance.

 

[rbtree]

I agree that the only reason for a low oil ratio is to insure that the saw always has adequate lubrication. That said, I've been running full synthetic Mobil Racing 2T for many years at about 36 to 40-1 with zero issues with carbon buildup. My supply's about to run out, then I'll switch to a product Klotz, most likely, as it is well liked and economical.

 

[Al Smith]

Gordon Jennings ,Bell and Mac Dizzy pretty much cover the effects long term of mix oil ratios .A subject I'm not going to argue about .I'll only say this the old outboard boat motors that ran heavy oil mix didn't foul plugs or carbon up unless you set the carb mixture extremely rich .Even if then and if they still ran you just lean them up a tad and run the snot out of them for ten minutes and they cleared right up .

Actually the only time they fouled was running at trolling speeds ,never at cruising speeds .

Stop and think about it though .Most saw racers use heavy oil and they don't have a problem .That said I say run what you're comfortable with and which ever brand you like .

 

[woodworkingboy]

Roger, do you use premium gas? I wonder if that could effect lubrication requirements.

 

[sotc]

50:1 with premium, never burnt up a saw yet

 

[GASoline71]

I mix my fuel at 50-1 but I use premium gas and a premium synthetic mix oil. If it's crappy gas or cheap oil, then more isn't going to help much. Using the best oil I can means I don't have to use extra to compensate for its shortcomings.

Exactly... the premium fuel and the QUALITY full synthetic oil at 50:1 is more than adequate.

Gary

 

[wiley_p]

Jeez. 48.35:1 with 100 octane low lead.

 

[woodworkingboy]

100 octane seems pretty high for pump gas premium in the states. That's what I buy over here, by law it has to be 100 or above.

 

[SkwerI]

I think they are different scales, Jay. Just as an English gallon is not the same as an American gallon (but some Brits still rag on us all the time about fuel economy without taking the difference into account).

 

[woodworkingboy]

Ahh...

 

[squisher]

I run 50 to 1 and have also never cooked a saw. Premium always.

 

[Burnham]

Ditto.