These have a passage to connect the H and L if I remember right.
A business down the street from me just had a 14 foot bar made for a 3120 to buck old growth redwood stumps. Can't wait to post pics. They said it took a few minutes for the chain and bar to break in then it cut good.
A business down the street from me just had a 14 foot bar made for a 3120 to buck old growth redwood stumps. Can't wait to post pics. They said it took a few minutes for the chain and bar to break in then it cut good.
If you have a saw with a fixed high jet, it would not be wise to run more oil in the mix than what the jet is sized for... If it's meant for 50:1, running 25:1 will make it run lean...
Not a good scenario... On an adjustable carb, no sweat, but if not, beware...:msp_mellow:
Its the same volume of mix per air volume going in. Normally we think of lean meaning less mix, more air. In this instance, it is the same, just more oil, less gas, with the same air volume. Exact same ratio of mix to air. I cant see this being called lean, I think better just call it richer in oil.
With the same exact carb settings, have you ever seen a saw run hotter with 25 to 1 versus 50 to 1? Or lean seize running that ratio, given an appropriate carb setting?
I am just asking, I dont know, I have just read that description here before with higher oil ratios being lean..aint seeing it, you havent changed the air volume.
I dont know where semantics leaves the engineering here.
Way back we were running dino oil at 16 to 1, (or the heavy glug glug glug measuring method...) why no lean seizes then? It was smoky and stinky, but no lean seizes if it was adjusted correctly.
I dont have enough experience with modern saws running different oil ratios. Just wondering is all. Be interesting with a infrared thermometer reader toolm whatever those things are, I dont have one..
Oil does not flow through the same size hole at the same rate as gasoline... When the oil ratio is raised, your liquid to air ratio is cut, you get a lean condition... Remember, the fuel mixture doesn't just lubricate, it cools...
Lower the ammt of liquid, and cooling is reduced... "lean condition" and aluminum transfer can happen due to temps... Old saws ran fine at 14:1... Because that's what they were jetted for. Mix em a batch of 50:1, and see what happens without the ability to lean out the high screw...
Fat as hell...
i had a fixed jet 3120 that had a great big sticker on it from the factory that said 25:1. yes it was a fixed jet saw. i happen to be one of the guys that can do an adjustable carb for the 3120 so i just fixed that little problem and continued on with my day. anyone needing a high speed screw put it to a non adjustable wg give me a shout.
Yes, but I think oil lubricates and cools as well. Lubrication is the oils job ater all. Not sure on the jetting and the flow, I imagine modern synthetics break down into rather small micrdroplets compared to old dino oil. Dont know if there is all that much difference in most newer saws where it would kill the saws shortly to run it oil rich. Maybe carbonization?? dont know how far you could push it.
With that said, I ran 50 to one for a long time, but 40 seems to work better, but I dont have anything to back that up accept what it feels like to me and how the saws run. I switched in that nasty heat wave last summer. I have read here some guys are running 32:1 in all their saws all the time, apparently without troubles. 25 to 1, dont know.
Id really like to see a proper test with some numbers. I have an old whatever kicking around, Ill do a small test tank at 25 to 1 sometime, if it seizes up, Ill post pics.
Sorry zog... I know I'm terrible at explaining stuff..
nah... I got your point the first time. Sounds like the fix lies with tlandrum and fixing the "H" jet...
I have a fixed jet 3120 also, with the sticker that says 25:1. I have been running about 40:1 in it without problems. I would be interested in having it made fully adjustable. Is this something you could do a thread on how to do, or is it a service you provide? How much? I think I saw another person post that it isn't too hard to do, but they didn't give any explanation or instructions.
Enter your email address to join: