Premix ratio for vintage bike

Discussion in '2 smokers' started by cdahl383, Aug 16, 2020.

  1. cdahl383

    cdahl383 Adventurer

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    I’ve got an old Suzuki PE that calls for 20:1 premix. Seems to run just fine on this (no ethanol fuel with yamalube 2R) .

    Heard from others it’s too much oil, oils are better now than in the 70s, etc. I should be running 32:1 or 40:1.

    What are you guys using on your old bikes and what seems to work best?

    2E26BD22-B9A9-456A-A8D9-CD189277392B.jpeg
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  2. mikeysduck

    mikeysduck Slow Ride to Nowhere

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    Bikes were running 20:1... Racing bikes 16:1, back when. Be prepared to re-jet the bike to match the new ratio you choose.
    Good looking ride.
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  3. bobfab

    bobfab Long timer Supporter

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    I think another big consideration is the type of oil, #notanoildebate. There is a big difference between Yamaha type s and the silkolene I rub in my modern ktm e-xc! The oil bikes seem to want this really thin premix
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  4. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    I grew up racing little Hodakas and other little two strokes. In my first Hodaka, back in the late 60's, I ran regular old Pennzoil 30 weight motor oil at 20:1. Not a big deal and except for a bit of carbon build up. Of course back then there were no mufflers clog up, we ran straight "stingers". I was recently given a completely stock Hodaka Ace 90 in which I now run Yamalube at 40:1 no issues.
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  5. AlpinaE24

    AlpinaE24 Long timer

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    klotz r50 at 40:1 for everything
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  6. snarlyjohn

    snarlyjohn Human money repellant

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    Ask ten different people and you'll get ten different recommendations, often fervently supported. The truth is that unless you run something with an especially high specific output - in which case you'll be in castor territory - damn near any oil at any reasonable ratio will be fine.
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  7. cdahl383

    cdahl383 Adventurer

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    I’ve been running 32:1 with 91 no ethanol fuel and yamalube 2R. Stock jetting. Seems to run just fine like this.

    Here’s a pic of my plug (BR9ES). Looks pretty good so far.

    Attached Files:

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  8. 1wicked55

    1wicked55 Been here awhile Supporter

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    Ditto
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  9. KennyV

    KennyV Been here awhile Supporter

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    I been running Yamalube 2R @ 32:1 premix, 93 non ethanol my Yamaha DT250A with stock carburetor jetting for 15+ years. Runs great no issues.
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  10. SandSpider490

    SandSpider490 Adventurer

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    My '83 Maico's factory owner's manual recommended Maico MC-GP 100 oil at 100:1 ratio. Alternatively, it recommended Bel Ray MC1 at 50:1. I've owned Maicos since 1980, and back then we did run the Maico oil at 100:1 and never had a single issue. No idea what wonder oil that was, but it's ancient history now. The Bel Ray is still available, so these days that's what I run at 50:1.
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  11. WooPig

    WooPig Redundant Supporter

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    100:1 in ‘83, wow. I bet that oil was expensive!
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  12. PSchrauber

    PSchrauber Long timer

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    Nope not expensive Bultaco had too 1:100 mixture.
    The Bultaco oil was OPTIMOL from Munich in Germany.
    Optimol then went to ths US and is still making that 2stroke oil.
    Helmut Ckasen now livung in Canada Ontario is still advertising that oil.

    But we have now gasoline that have a lot of other stuff inside thus I would not try that out to old machinery any more.

    I seperate by the bearings of the upper piston pin with. If a roller cage bearing is mounted you can use 1:50 up to 1:75 that is at least what I do.

    With engines where the upper pistonpin has no bearings I would use 1:25 to 1:33.
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  13. Euromad

    Euromad Been here awhile

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    Another thing to remember is less oil = a richer gas mix. I have a lot of vintage two strokes. I use a modern oil that can be mixed to 36 to 1 (1970 CZ 250, 1973 CZ400) ratio or 40 to 1 (82, 83 Husky CR and WR). I have heard some modern oils may not mix well at those ratios, dropping out of suspension. With an air cooled motor ridden in anger I want extra insurance against a seizure. A friend owns a 74 Husky 400 and it has seized twice. The jetting was richened up after the first seizure. He was running 50 to 1 and it wasn't enough lubrication.
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