Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

tore the carb off a friends 35 yr old chain saw and cleaned  and reinstalled it because it would quit when the throttle was returned to an idle. ended up being the vacumn tube at the back off the carb was bulged at the fitting and leaking air.installed new hose and put back together. set the mixture screws each to  1 turn out(couldn't get it started) and then to 1 1/2 turns and it finally did start. once running i adjusted the low and high speed to mid point of lean and rich rpm drop and it starts and runs great,only problem is it will not idle down like it should.it runs slow enough to keep the chain from spinning but the rpm's are a bit high.i can back the idle speed screw out so the throttle plate is completely closed and it makes no difference. i can slow the rpm's by leaning the slow mixture jet  so i beleave they are not damaged or the problem. that's about all i know how to do! anyone have any ideas why it won't idle down like it should?

If you can get it to idle slow enough not to engage the clutch, that's all you need to do. 

I used to own one of those saws.  You should be happy that it runs at all.  My 310 was the worst piece of junk I've ever owned.  Thankfully the casting that held the ignition module broke off rendering the saw even more useless.  Accordingly, it went in the scrap pile and I bought a real chainsaw, a Jonsered 630.   Be happy with the way it is.  

Yep - Mr. Borat is certainly correct.  The MAC I owned probably would not even make a good boat anchor.  Works just as well with or without the ignition module.  Got a JD now that works well for me.

as stated in my first post it's not my saw.just trying to get it running for a friend. it had the vacumn tube i'll fitting at the carb and also a small pin hole.replaced the hose  as well as fabed a new throttle cable. i did finally get it to idle down enough for the chain to quit moving.it also needs a new bar and the clutch outer housing has some play on the shaft. is that normal?also how much oil should it go thru per tank of gas? i've turned the auto oil feed down some cause it seems to puddle at the bottom and sling oil everywhere. i do have a mcculloch 610 that has served me well for 22 yrs. it's really heavy though!

Can't help you too much with your queries.  It's been close to 30 years since I owned my Mac and while I did own it, didn't get much use out of it to remember anything of importance other than how shabby a saw it was. 

Generally speaking, I fill the oil reservoir with each fuel fill on my saws.  It's the safest way to do it. 

mkd55 wrote:

Borat is correct. Also, you can point the bar tip at a fresh cut stump or log and rev the saw for ~5 seconds, you should see little drops of oil spatter against the white wood. If not, turn it up some more.
In general you should go through almost a tank of oil for each tank of gas, at least on the saws I've had. Can't say it's the same for all brands.