Oil fuel mixture (more is not better)

Discussion in 'Motorized Bicycle General Discussion' started by tyrslider, Oct 2, 2008.

  1. tyrslider

    tyrslider New Member

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    I see a lot of threads of people using too much oil. This is not adviseable. If you use too much oil w/ out using a larger jet you are actually running leaner. Only so much mixture can go through the hole in your jet, so if you have a higher ratio, i.e. more oil in your gas, then less gas is going through (lean condition is the enemy of 2 strokes). So even though you have more oil you can still sieze your motor and even if you don't sieze, your motor will run hotter, you will probably lose power and you'll have to service your motor more often. The appropriate octane gas, burning properly will also regulate engine temp. I'll leave it open to others w/ more "bicycle motor" experience what gas is better, But I would think w/ only 6:1 compression 87 octane (regular) is best. But just as an example I built a Yamaha rd 350 w/ 70 hp, 10:1 compression (stock is 37hp) and ran 110 octane leaded gas at 33:1 mixture. More is not necessarilly better!(p)
     
  2. CalgarysFool

    CalgarysFool New Member

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    An RD 350 with double the original HP? I'd love to see that -- Not ride it myself, but see it. That is one of my most favorite bikes of all time!

    I'm a tad worried about oil mixture now. Spookytooth advises 20:1 at break in and ever after! I've read many alternate suggestions here, but this is the first time I've read that my 20:1 plan may be a bad idea.

    I'd really like to hear more about this, so I can be better informed as I get beyond my break in period.

    Thanks in advance, guys and gals, for any contributions here.

    Brenton
     
  3. OSCAR383

    OSCAR383 New Member

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    i ran 20:1 my first 2 gallons , 4 tanks, and now i run 32:1 on good ol 87 octane
     
  4. MrLarkins

    MrLarkins HS Math Teacher

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    i put 4oz oil to 1 gallon gas.
     
  5. FileStyle

    FileStyle New Member

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    4 oz. to the gal.
     
  6. misteright1_99

    misteright1_99 New Member

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    Yep 32:1 quality oil........
     
  7. old motorbike

    old motorbike New Member

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    I'm using 16:1 oil the first week and it still 4 cycles some of the time, mostly at higher revs. (isn't that too rich?)
     
  8. misteright1_99

    misteright1_99 New Member

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    No that is what the instructions recommended for my engines also. It helps get everything seated and broken in..
     
  9. tyrslider

    tyrslider New Member

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    Calgarysfool my RD did 3rd gear wheelies (no lie). You could pull up in 4th goin' 60 next to some guy on a modern sport, drop a gear, pull the front off the ground and start shiftin up before she flipped over on ya. rotfl A guy I was trading parts w/ in AK was putting 100 hp to an RD 350 Drag bike.(p)

    I hope no one understood me to be suggesting any particular ratio. It's just that I seem to run into the misconception of more oil is better in the m/c community and I noticed it a little here. These are obviously not high mileage motors but it sure would be interesting to know how far some of the higher mileage motors have gone and what their owners did to make'm go that far. There are a lot of factors in choosing a ratio and I don't claim to be any sort of expert on the subject, I just have a rudimentary understanding. On unmodified engines, the manufacturers instructions should be accurate. However, That being said These motors are made in China and Indonesia and probably other local's as well. Poor translation into english , quality of oil available in that particular region compared to quality of oil you use, petro vs synth, these are just a few complicating factors. In truth you want to use just enough so that it doesn't seize no matter how you ride within reason. You should use the highest quality oil you can afford and that is readily available to you i.e. don't switch oils often, find a good one and stick w/ it. Some of the race quality oils will give you guidelines to follow. Just like a 4 stroke, your plugs should be light brown but not tan and power should be crisp. If thats the case and you've been ridin' around without seizin' your probably fine. :ride:

    I haven't read of any seizures so far!(^)
     
    #9 tyrslider, Oct 4, 2008
    Last edited: Oct 4, 2008
  10. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    That's too much oil.

    If it 4 cycles with that mix, it will surely 4 cycle when you go to 24-32:1 mix.

    Most of the "instructions" that come with these bicycle motors suggests using 16 or 20:1 because that would be the correct mix with ancient, 30 wt. motor oil.

    Too much oil will cause rings to stick (really bad) and excessive carbon build up.
     
  11. tyrslider

    tyrslider New Member

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    I would echo BG Joe on the "mis"recomendation. Does 4cycling = misfiring or dieseling or? I've never heard that one.
     
  12. CalgarysFool

    CalgarysFool New Member

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    My instructions said to use 20:1 with synthetic -- is this a less than complete effort to modernize those out dated instructions?

    Anyway, thanks for this explanation, BGJoe -- but now I'm at a loss. I know this is going to be asking for 40 different recommendations, but, I'm still on my first tank of gas--early in the break in period--what should my mix be?

    Thanks guys.

    Brenton
     
  13. velardejose

    velardejose New Member

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    Hi
    Talking to the motorcycle mechanic who replaced my main bearings
    He told me 30:1 is a good number as long as it doesn't foul plugs
    Peace
     
  14. ibcnya

    ibcnya New Member

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    "4 cycles" What does this mean?
     
  15. old motorbike

    old motorbike New Member

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    A 2 stroke fires every stroke and sounds smooth. if the fuel mixture is rich or the engine is under a light load, it may start firing every other stroke (like a 4 stroke engine does) and develops a different stuttering sound and loses power.
     
  16. ibcnya

    ibcnya New Member

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    Ok so mine is doing this....Should it stop once I start putting less oil in the gas. Rite now its 5.5oz to a gallon. Sometimes it does it and sometimes it doesnt. Mind you that im only on my 3rd tank of gas...still 20:1 fuel.

    im also having problems with fuel running out of my air filter, when this happens I have to kill the gas at the petcock and peddle through the flood until it fires up. What is my problem and how can I fix it?
     
  17. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    It will actually get worse when you go to a mixture like 24:1 or 30:1. You will have to move your needle clip up a notch. Also may want to clean your air filter since it's clogged with fuel and oil.

    Check to make sure your float isn't sticking when it does that....tap the float bowl.
     
  18. Mr.2Tcycles

    Mr.2Tcycles New Member

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    Could be you have dirt in the carb too. Happened to me and it was really leaning out the mixture. Gas was just flowing out the carb when stopped, this was caused by dirt getting stuck between the needle and the seat so fuel just kept flowing out the bowl vent hole. Take your carb apart and clean out the bowl, and spray carb cleaner through the jet and fuel inlet in both directions. Don't know if you have a inline fuel filter, if not get one.
     
  19. ibcnya

    ibcnya New Member

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    Checked my needle position in my carb today and it was on the bottom slot, Moved it to the second to top position and throttle isnt boggy now like it was before. Rode about a mile, checked the plug after cool down and can tell its better.
     
  20. tecker

    tecker New Member

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    yea know I just slapped my bike together as it came out of box everything was pretty much put together didnt adjust any thing put 30/1 gas mix had kill switch wrong but took it off and it started first try I used wally world oil a little bottle that came with a measure thing in the top it was made for 2 cycle engines
     

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