Oil mix for older saws

[cgarman]

I just got my hands on a Stihl 076AV for milling slabs up to 48" on my Granberg mill. I used to run it on a Dolmar 7900, and a mix of 50:1 seemed fine. I've heard folks say that older saws like the 076 used to use at most 32:1. I've even heard some say they go to 16:1 for milling, but that seems too far to me.

Any thoughts on how to mix for a granddaddy 111cc saw that has its work to do in cutting red oak and maple all day, about 4 days a month?

 

[Brmorgan]

I just got my hands on a Stihl 076AV for milling slabs up to 48" on my Granberg mill. I used to run it on a Dolmar 7900, and a mix of 50:1 seemed fine. I've heard folks say that older saws like the 076 used to use at most 32:1. I've even heard some say they go to 16:1 for milling, but that seems too far to me.

Any thoughts on how to mix for a granddaddy 111cc saw that has its work to do in cutting red oak and maple all day, about 4 days a month?

It's perfectly safe to run old saws at modern mix ratios if you're using modern oils. If not safer, in fact, because those old beasts run slower and cooler than modern saws to start with. I run 40:1 for everything just because I don't feel like mixing two jugs of gas. Carbon buildup hasn't been an issue either. 16:1 might be a good idea during the height of mosquito season; you'd be doing more harm than good in the long run with that much oil though.

 

[Trever]

32:1

It's perfectly safe to run old saws at modern mix ratios if you're using modern oils. If not safer, in fact, because those old beasts run slower and cooler than modern saws to start with. I run 40:1 for everything just because I don't feel like mixing two jugs of gas. Carbon buildup hasn't been an issue either. 16:1 might be a good idea during the height of mosquito season; you'd be doing more harm than good in the long run with that much oil though.

For what it's worth (not much), I use stihl mixed 32:1 in my 075 when milling. Spark plugs are cheaper and quicker to change than burnt/ scored pistons.

 

[cgarman]

For what it's worth (not much), I use stihl mixed 32:1 in my 075 when milling. Spark plugs are cheaper and quicker to change than burnt/ scored pistons.

I assume you're saying that you noticed the plug getting fouled a lot quicker with a higher mix. That's interesting, because I was wondering if I need a new plug anyway.

All I know it something is not right. If I can stall the saw while milling 16" oak, there's a problem. I know the air filter is dirty, so I'm soaking it in gas today by suggestion of BobL. The guy I bought the saw from said he tuned the carb rich to protect the engine. I don't know much about carbs, so I haven't touched it yet. Compression on the saw was decent - 120 psi, with no leak - so I feel like I'm missing something obvious. I thought maybe the higher mix ratio was harder to combust, and that was to blame. I guess not.

 

[smokinj]

I assume you're saying that you noticed the plug getting fouled a lot quicker with a higher mix. That's interesting, because I was wondering if I need a new plug anyway.

All I know it something is not right. If I can stall the saw while milling 16" oak, there's a problem. I know the air filter is dirty, so I'm soaking it in gas today by suggestion of BobL. The guy I bought the saw from said he tuned the carb rich to protect the engine. I don't know much about carbs, so I haven't touched it yet. Compression on the saw was decent - 120 psi, with no leak - so I feel like I'm missing something obvious. I thought maybe the higher mix ratio was harder to combust, and that was to blame. I guess not.

48in. mill is a big one and in oak as well 120 seems a little low to me as well.
Your on the right track I would make sure the chain is razor sharp all the time

 

[Trever]

051

All I know it something is not right. If I can stall the saw while milling 16" oak, there's a problem. I know the air filter is dirty, so I'm soaking it in gas today by suggestion of BobL. The guy I bought the saw from said he tuned the carb rich to protect the engine. I don't know much about carbs, so I haven't touched it yet. Compression on the saw was decent - 120 psi, with no leak - so I feel like I'm missing something obvious. I thought maybe the higher mix ratio was harder to combust, and that was to blame. I guess not.[/QUOTE]

Get some carb or brake cleaner and spray the junk off the clutch side of the carb so you can see the 2 screws. The other screw that is part of the carb base plate is the idle speed adjustment. When you spray the carb body, you should be able to see an H and L. The L will adjust the low speed jet and the H will adjust the high speed jet. If the saws starts fine and runs sideways, upside down, and does not hesitate ot stammer when throttled then the L screw is set properly. If the saw does not run at these angles( a little rich), then the L screw needs to be turned clockwise a little. Make very small adjustments on any carb (1/16- 1/8 turn). Clockwise turns on both screws make leaner settings. Counter-clockwise adjustments make richer settings.

Now for the H screw. Make sure the saw is at operating temperature and the chain is on. Count how many turns it takes to screw the screw all the way in (clockwise). Make sure you do not damage the carb's body by tightening the screw to hard. Now, back the H screw out 1 1/8 turns for the initial setting.

Have a blessedday.

Trever

 

[cgarman]

So, as I'm backing the H screw out, how do I know if I've gone too far? I don't want to burn up the piston - that's for sure. Am I just being too paranoid?

I've been told to check the plug occasionally, to make sure it doesn't turn white, as an indication that the mix is too lean. Right now, it's brown and oily. Brown seems right. Oily seems bad. My thinking is that I should reduce the gas mix (32:1 now) to 40:1 and set a leaner H setting. Then again, I have no idea what I'm talking about.:dunno:


I really appreciate all the help I've been getting on the forum.

 

[smokinj]

best way to explain it
http://web.archive.org/web/20051018212959/www.madsens1.com/sawtune.htm

listen to the sound wave!

 

[Mr Good Wood]

i got a old mccullough 250 super, wonering the gas/ oil mix ratio to use? also the biggest bar that i can run on it?

 

[smokinj]

i got a old mccullough 250 super, wonering the gas/ oil mix ratio to use? also the biggest bar that i can run on it?

post it in the chainsaw fourm many mccullough Fans in there.

 

[cgarman]

best way to explain it
http://web.archive.org/web/20051018212959/www.madsens1.com/sawtune.htm

listen to the sound wave!

Very helpful.

Listening to that, it seems like I can figure it out. I can definitely hear it in the top of the rough zone. Now I just have to figure out where the H screw is on the 076. Should I be able to see it after pulling the air filter?

 

[smokinj]

Very helpful.

Listening to that, it seems like I can figure it out. I can definitely hear it in the top of the rough zone. Now I just have to figure out where the H screw is on the 076. Should I be able to see it after pulling the air filter?

once you hear it you will always have it but some are tone death so you are not! lol

 

[BlueRider]

If you use a high quality full synthetic mix oil you can run your saw at the same ratio as any new saw. I have been running 50:1 for milling in my vintage stihl for over 15 years. I used to mill with an 051 which is the 89cc little brother to your saw. For the past couple of years I have been using an 051 that I converted to an 075. My prefered oil is Stihl HP Ultra.

120 psi is on the low end. Now might be the best time to open it up and address it as it may be that a new set of rings and a new gasket set are all it will need. that should set you back less than $50 if you use factory parts and $20 if you use after market rings.

There is a great service manual for your carb on the Tillotson web site. your saw uses the HS series carb.

 

[cgarman]

Thanks for answering 3 questions of mine at once!

The guy I bought the saw from said it pulled 145 psi. I can only get 120, so I'm trying to give him the benefit of the doubt, but it's getting harder. The setup is fine, because I checked my friend's Dolmar at 165 psi.

Any idea what the compression should be if I change them out?

Bailey's has the rings for $12, and a gasket for $5. I'm pretty handy with a socket set, but I've never opened an engine before. Is this beyond my over-optimistic DIY skills?

 

[BlueRider]

It's pretty straight forward remove and install type stuff. The only tricky part is adjusting the carb and that is something you really should learn anyway. for gaskets you will need the cylinder base gasket and exhaust gasket and two intake gaskets.

A carb rebuild at the same time might not be a bad idea. the only trick to doing the carp is to take a paper shafted Q-tip and shepend the cardboard/paper part and use it with a drop of light oil to hone the valve seat in the carb that is not remove able.

You should be getting in excess of 150 psi. With fresh rings you will need a compression release when starting.