Break in period with low oil to gas ratio

Discussion in 'Motorized Bicycle General Discussion' started by arguevera, Jul 16, 2017.

  1. arguevera

    arguevera New Member

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    Some backstory first:
    • Engine is a typical ebay 80cc 2 stroke kit
    • When I first mixed the fuel, I negligently calculated the ratio wrong and ended up with 2 gallons of mixed fuel with a ratio somewhere between 32:1 and 40:1.
    • I have used up almost the entire 2 gallons.
    • The bike has been rode for around 100-150 miles so far (for the past 20 days).
    • The climate where I live is generally cool (San Francisco)
    • During this break in period, RPMs ranged between low and high, but cruising was always low to medium.
    • During this break in period, there was a lot of uphills (SF) and in some cases I had to assist by pedaling.
    • Break in period seemed to go good as the engine developed a lot of power during the period.
    • Engine has no problem starting or idling
    Basically I just realized I have been running with quite a low oil to gas ratio for the break in period and was wondering if it seemed to have gone great, is there any underlying damage that could have occurred? For example, I know that piston and cylinder walls can be scored and damage can be done to the piston rings, but all those would result in a loss of power. If my power has only been improving during the period, can I assume that no damage has been done?
     
  2. Chaz

    Chaz Active Member

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    Welcome to the forum. I would say that you don't have anything to worry about. I have read here that many very experienced builders will use the mix ratio that they plan to use permanently as the break in ratio as well. There are many opinions on breaking in but I believe the key is just don't overheat and vary the rpm which is exactly as you did so you're fine.
     
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  3. arguevera

    arguevera New Member

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    Thanks for the reply! So in all, since there was no catastrophic failure and the engine power increased during that time, the worse that could have happened was some increased wear?
     
  4. Chaz

    Chaz Active Member

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    You did everything right. I would say you've only got normal wear.

    I don't know what oil you are using but for long term use I think full synthetic is the way to go. I followed some advice here and on one engine I used dino oil for the break in and then switched to synthetic. The theory is that synthetic is too slippery for break in and may not seat the rings properly. Who knows, but there is some logic to it and it worked fine for me.
     
    #4 Chaz, Jul 17, 2017
    Last edited: Jul 17, 2017
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  5. arguevera

    arguevera New Member

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    Okay sounds good, thanks for the advice!
     
  6. xseler

    xseler Well-Known Member

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    All above is correct. 'Broke' mine in at 32:1 for the first gallon. Run it at 50:1 thereafter. It's been 4 1/2 years now ---- it runs better now than when it was 'newer'! I've only ran synthetic Echo oil since the beginning.
     
  7. TheSignGuy

    TheSignGuy Member

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    Nah,


    Typically break in is 32:1 ratio after that is about 40:1- 50:1



    Lower ratio helps marry the rings to the walls you should be OK just never break in at 40:1


    Won't provide enough gas to oil lubrication during break in at 480 miles would be nice to do a high synthetic quality oil to promote longer life.


    Sip scooter shop sells scented oils as well lol just saying 500miles is the actual full broke in period for motorized bicycles, mopeds, etc.


    The good thing is that:

    You did the light break in,

    If you where a racer some people believe in fast and hard break ins the difference between the two is that race engines are frequently torn down.


    If you broke it in wrong your motor would have either A: broke down at minimum of 150 miles or B: had a dieseling problem when you cut the ignition supply which is referred as run on.
     
    #7 TheSignGuy, Sep 3, 2017
    Last edited: Sep 4, 2017
  8. Tyler6357

    Tyler6357 Member

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    When you are breaking your engine in the piston rings will grind down and conform to the cylinder. When this happens small amounts of metal shavings from the rings break off, this causes increased friction and so it is recommended that you use a little extra oil in your mix. The extra oil helps keep the temps down and to help wash the metal shavings out of the crank case. Since you really didn't add extra oil, it probably broke in a little hot, but as long as you didn't take super long rides and stopped to let it cool now and then than its probably fine. During break in it's best to drive it for a while and then stop and let it cool down. Metal will expand and contract slightly as it heats and cools.
     
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  9. Citi-sporter

    Citi-sporter Member

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    Using a low oil to fuel ratio is a good thing, as long as the engine is tolerant of running on a light oil mix. These engines have a chrome liner, which don't need an extensive break-in. If the engine was of yard implement quality, they wouldn't need much if any break-in, such as a Husky/Echo/Tanaka weedieater or small chainsaw, which can be run on straight 40:1 out of the shop/shipping box.

    The other thing is you're running a 'rich' fuel mix. This is not a bad thing. I don't know if anyone is using the 'recommended" 16:1 break-in on dino anymore with these ChinaGirl engines. It's a bad idea as it is, because you should richen, ( increase the fuel to air mixture..) of your jetting when running 16:1 to keep the engine from overheating from being too lean on fuel mix. These new synthetic 2 cycle oils are far superior in lubricating at 40 to 50:1 ratios as it is.

    In other words you did good. Now we'll find out what CA street legalities are required for these bikes, theoretically they should be listed as a motorcycle and require a license and insurance, but a lot of members of this forum, who live in CA install and run these 66cc engines on their bikes, and it seems to pass.
     

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