(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 12 of 12

Thread: 2 Stroke Engine Fuel Mix Ratio

  1. #1

    Default 2 Stroke Engine Fuel Mix Ratio

    My leave blower needs 40:1 gas to oil mix.
    My weed trimmer needs 50:1 gas to oil mix.
    It is a pain to keep a separate gas container for each mix.
    What happens if I just keep one container with 45:1 mix?
    Will I damage the engine?
    Will performance be worst?
    Difficult to start?
    Last edited by xroad; 11-02-2008 at 06:06 AM.

  2. #2
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,655

    Default mix

    use 50:1 mix. The trimmer will just smoke a bit more and the spark plug may foul a bit more often.

  3. #3

    Default

    Quote Originally Posted by hj View Post
    use 50:1 mix. The trimmer will just smoke a bit more and the spark plug may foul a bit more often.
    If I use a mix with more oil, 40:1, it will smoke more. So did you meant to use 40:1 ?

  4. #4
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    Pro-Mix Premium cam be used safely for engines requiring between 16:1 and 50:1. It comes in a container that measures out 2.6 oz for a gallon of gas. You can buy it Slowes, I think.

  5. #5
    DIY Senior Member Nate R's Avatar
    Join Date
    Jan 2007
    Location
    Milwaukee, WI
    Posts
    472

    Default

    Go ahead and use the 40:1 in both.

    I work w/ small engines for a living on the R&D side, FWIW. You will not experience much difference at all. As was said, the trimmer *might* smoke a bit more and may go through plugs a little faster. But honestly, I doubt the difference will be perceptible.

  6. #6
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,655

    Default mix

    yes, I did.

  7. #7

    Default

    Thanks folks, and I thought this is some precision mixing requirement.

    What would happen if I run 50:1 mix on te engine that needs 40:1? Not enough oil = more wear on the engine?

    What would cause my trimmer to run fine at half throttle and seems to start to loose power as I open the throttle beyond half throttle? Would too much oil be the cause?
    Last edited by xroad; 11-02-2008 at 04:59 PM.

  8. #8
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    Quote Originally Posted by xroad View Post
    Thanks folks, and I thought this is some precision mixing requirement.

    What would happen if I run 50:1 mix on te engine that needs 40:1? Not enough oil = more wear on the engine?

    What would cause my trimmer to run fine at half throttle and seems to start to loose power as I open the throttle beyond half throttle? Would too much oil be the cause?
    If you don't have the right kind of oil you could burn out the motor.

    The carbs on these usually have different mixture needles for idle and high throttle. You're either too lean or too rich on the high end. Read the owner's manual for method of adjustment.

  9. #9
    DIY Senior Member Nate R's Avatar
    Join Date
    Jan 2007
    Location
    Milwaukee, WI
    Posts
    472

    Default

    Quote Originally Posted by Southern Man View Post
    If you don't have the right kind of oil you could burn out the motor.

    The carbs on these usually have different mixture needles for idle and high throttle. You're either too lean or too rich on the high end. Read the owner's manual for method of adjustment.
    Many of the newer small 2-strokes are starting to come under emissions regs, and have anti-tamper devices on the carbs, or offer very limited adjustment. You might find this is not possible. Engines this small tend to have carbs that vary widely as well from one to another. You may be stuck with the problem. It may have been a carb calibration compromise made for emissions.

    It could be caused by too much oil. Plug could be fouled. Could be too rich or lean on the high speed adjustment.

    Using 50:1 in the engine that calls for 40:1 *might* work. There has to be some margin of error there. But it may be lean enough on oil to seize it. Often times, if you don't run enough oil in the mix, you don't just have small problems. You don't know there's a problem until it's too late. You'll either seize it or score a rod bearing so bad that it will never run well again, etc. But where that margin is you'll never know until you go too far. :-) Safer thing would be to have the 40:1 used in both.

  10. #10
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    Quote Originally Posted by Nate R View Post
    ....

    Using 50:1 in the engine that calls for 40:1 *might* work. ....
    An older engine that calls for a richer mixture can use less if a synthetic oil is used. But don't take my word for it- take a manufacturer:
    What is the correct oil mix for my older STIHL chain saw, trimmer, or blower?
    STIHL recommends a 50:1 mix when using STIHL branded two cycle mix oil (2.6 oz. of STIHL branded oil for 1 gallon of gasoline) on all of our gasoline powered equipment.
    http://www.stihlusa.com/faq.html

    I've used Pro-Mix for several years now, including in my Old McCullough chain saw. It smokes less and I never have plug fouling problems.

  11. #11
    DIY Member eldyfig's Avatar
    Join Date
    Nov 2008
    Location
    Folkston, GA
    Posts
    32

    Default

    My blower and trimmer call for the same ratios as your's do, xroad. I have used one container mixed at 40:1 for both of them for a few years now with no problems.
    Tony F.

  12. #12
    Like an engineer alternety's Avatar
    Join Date
    Apr 2006
    Location
    Washington
    Posts
    636

    Default

    I have been using Amsoil synthetic at 100:1. The manufacturer claims this is OK for any 2 cycle engine. I have used it in a chainsaw and a string trimmer. I have used the trimmer for about 15 years and the chainsaw for 30. But not a whole lot at any time. The chainsaw started with regular oil I think. No idea how many hours are on them. Nor have I taken one apart to look at the cylinder and other assorted parts. Maybe someday I will open the chainsaw ans look; it is dead. No - not the engine. The drive sprocket is worn out and I can't get it off.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •