2 cycle Warning! Don't run out of fuel

Discussion in '2-Stroke Engines' started by seabillco, Aug 1, 2008.

  1. seabillco

    seabillco Member

    Hi, all
    I ran out of gas in my 2 cycle friction drive MB.
    I didn't think much of it at the time. I was going downhill when the engine quit and I let the spindle stay down on the tire.
    The tire spun the hot engine for several seconds after the engine quit.
    When I got home and refueled, the engine wouldn't start.
    I then realized that what I had done was turn an engine at high speed with NO LUBRICATION due to the lack of fuel (with the oil)!!!
    I tore the engine down and, sadly, I ruined a very nice little engine. I had a broken ring and the crank's keyway was destroyed and the flywheel's keyway was reamed. I'm thinking the engine seized up and that caused all the damage.
    I was impressed to see that this particular Ryobi 31cc 410R engine from a tiller had needle bearings on the connecting rod at the crank. Very nice!
    I'll save the engine for parts but it's dead and not worth repairing.
    So, BEWARE!!! Don't run out of fuel if you're on a 2 stroke friction drive. If you do, STOP IMMEDIATELY!!!

    Steve G.
    Grants Pass, Oregon

  2. arceeguy

    arceeguy Active Member

    Good point!

    Also remember that your engine was probably running lean before it quit as air was drawn through the fuel lines before it finally stalled out.

    I am rebuilding the engine on my leaf blower (an inexpensive Weedeater), and noticed that the engine has needle bearings at both ends of the connecting rod like your Ryobi. You might want to check out what a new piston/cylinder set cost for your Ryobi. It was $22 for my 10 year old weedeater at a local power equipment shop. A few years back, I re-ringed the engine and honed the cylinder, which gave it a new lease on life, but the new piston/jug will get it going for a lot longer. (the rings were less than 5 bucks)
  3. seabillco

    seabillco Member

    Hi, arceeguy!
    Yes, you can hear the engine start to rev up just before it runs out of fuel due to the extra lean condition as you're running out of gas...
    And, yes, you are correct. I will check on parts before I trash it.
    Sadly, the crank (or power shaft assembly as they call it) is also shot. The keyway is thrashed up badly...
    Man, what a boner I pulled!! I trashed the crank, rings and flywheel all in one quick stroke!!!
    The flywheel was new and cost $40! The original had a cast key which sheared so I got a new one with a key way and a woodruff key. I thought I was set for a long time.
    Big Bummer!!!

    Steve G.
    Grants Pass, Oregon
  4. HI,

    Sorry to hear about your trashed engine....Thanks for sharing this though because it may help somebody else from having the same thing happen to them....

  5. kevbo

    kevbo Guest

    If you open up a HT engine, you will find about two or three tablespoons of oil in the crank case.

    It isn't so much the fuel mix that lubes these engines, as it is this oil in the crank case. The premix gets distilled by the heat of the engine, and this replaces oil that gets sucked through the transfer ports.

    Ocasionally I have noticed a little missing, or the engine doesn't want to idle...about 1-1/2 mile into a ride. I'm pretty sure that this when the crank case heats up enough to boil off the gasoline that has accumulated in there, and causes a rich mixture for a bit until it cleans up.

    Point is, you don't lose lubrication the instant you cut the fuel supply on the HT...you don't want to let it spin down a long hill of course, as you will eventually use up that oil.

    Also, it is a good idea to put about 1/2 - 1 oz of oil into the cranckase of a new engine before running it the first time if it is dry. You can just pour this in the intake port with the piston ~TDC.

    Note that this is in regards to horizontal shaft happy time engines. Chainsaw, weedeaters, etc. are made to run in all positions, and DON'T hold very much oil in the crank case...they do put various pockets to hold oil, but they are not as big as the space under the flywheels on a Happy Time. Basically anything supplied by the factory with a pumper (all position) carb.
  6. Skyliner70cc

    Skyliner70cc Active Member

    I had noticed same thing after every engine tear down that crank has a surprising amount of oil in it.

    Sorry to hear about your engine loss. Hope you get back on the road soon.
  7. seabillco

    seabillco Member

    Hi, again, kevbo
    Thanks for the information!
    Do you think ALL 2 stroke engines have this crankcase oil in them from the factory?
    So, the Ryobi would have it, too?
    If so, are you saying that the oil I mix with the fuel distills out while the engine is running due to the heat and then this distilled oil accumulates in the low end to lube the crank/con rod bearing and wrist pin, etc.?
    Have I got that right? So, the oil from the factory is constantly being replaced?
    Also, this may sound stupid but, how do I get access to the intake port on a new engine to add the oil?
    I have a new Ryobi engine. As far as I know, I'd have to remove the carburetor and its housing to get to the intake port. I can do that and add a little oil. Is there some better way to get the oil to the low end of a new 2 stroke engine.
    Finally, what kind of oil do I add? Do I just add some of the premix oil for 2 stroke or should it be normal 30 weight motor oil or something else?
    Thanks again for the information here and on the wrist pin post.

    Steve G.
    Grants Pass, Oregon
  8. Skyliner70cc

    Skyliner70cc Active Member

    Most of the oil that accumulates in a crank is from a slightly too rich idle mixture or idleing for long periods of time. This small amount of oil isn't necessary for proper operation of the engine as the bearing gets hit with fuel/oil mixture when fuel is drawn through the engine from the carb.

    For a first start on an engine, I always pour about 2 tablespoons of oil into the block to lube the bearings. I also put a small amount, couple of drops, on top of the piston so the oil leaks past the rings and helps the unseated rings generate compression for a start.

    I put the oil in the engine because many of my first starts require lots of pedalling before the engine fires up.
  9. seabillco

    seabillco Member

    Hi, Skyliner70cc
    Thanks for the tips.
    What kind of oil do you put in for a first start?
    How do you get the oil in the block?

    Thanks again!
    Steve G.
    Grants Pass, Oregon
  10. arceeguy

    arceeguy Active Member

    I totally agree with this. The engine does not depend on oil accumulating in the crankcase for proper lubrication. (and it is not desirable)

    For a "first start" of a new engine, I will sometimes give the engine a small shot of "fogging oil" (meant for storage of engines) for a little extra light lubrication. I personally wouldn't pour any oil in the crankcase. This will soak the sparkplug with oil and may cause starting difficulties. Then after the engine is started, the oil will burn, causing carbon deposits in the combustion chamber. The fogging oil will not impede spark plug operation. (Heck, sometimes I won't do anything special at all, I'll just start it up and let it rip!)

    First start and break-in rituals are largely personal preference though. If you ask 10 people, you'll most likely get 10 different answers. ;)