Rotary 2 stroke fuel mix ratio???

Discussion in '2-Stroke Engines' started by rooooboy, May 8, 2009.

  1. rooooboy

    rooooboy New Member

    hi guys,
    I recently purschased a second hand 2 stroke rotary engine. the ptrvious owner assured me he ran 25:1, as far as i can see from the manudacturer they recomend 50;1.

    i am a little concearned this may not be enough lubrication?

    any help or advice as i have just purschased thiis great bike.

    also anything else i should look out for???
     

  2. Old Bob

    Old Bob Member

    25:1 is twice as much oil as 50:1, exceeding the manufacturer specs for oil ratio is a common practice. More oil won't hurt anything, where less oil will.
     
  3. BoltsMissing

    BoltsMissing Active Member

    I run mine according to manufacturers book., 50:1 using high quality 2-stroke oil.
    Currently I'm using Castrol Activ 2T Jaso FC
    I have tried others, but it seems to like Castrol.
    Amsoil distributors say I can go to 75:1, but that's a choice owners have to make themselves, check with Rotary Australia.

    Note:
    MUST, use only genuine Bosch Spark Plug, WR10FC.
    The "R" is of most significance, stands for "Resistor".
    If you don't have that plug, it can fry the CDI instantly or while riding.

    Don't even attempt to start it if it ain't got the right spark plug.

    Gear Lube oil incase you don't know is SAE90.

    All the Best
     
    Last edited: May 8, 2009
  4. Mountainman

    Mountainman Active Member

    there is a thread poll -- recommended 2 stroke oil mixture is ??

    yes -- there has been much shared regarding this matter

    I like to keep them a little rich -- but -- that's just me

    as I ride my MB thing
     
    Last edited: May 8, 2009
  5. Skyliner70cc

    Skyliner70cc Active Member

    Running more than recommended oil ratio can cause the apex seals to stick. Running too rich oil mixture leans the air/fuel ratio and not good for a rotary. Rotaries typically run richer air/fuel mixture to reduce risk of detonation which can cause sudden engine failure. Detonation is very unforgiving on a rotary engine.
     
  6. Old Bob

    Old Bob Member

    I think we need a clarification as to whether this is a 2 stroke wankel type rotary or rotary/disc valve piston engine.
    Only a handful of manufacturers ever built Wankel engine type motorcycles, the engine were of size and capacity a little big for a mb.
     
  7. BoltsMissing

    BoltsMissing Active Member

    2 Stroke engine, similar to a Sachs, just the name is differant.
     
  8. Old Bob

    Old Bob Member

    I looked up Rotary, they make an interesting unit.
     
  9. heathyoung

    heathyoung Member

    Its just a brand name, not a rotary style engine - ie. Piston, 33cc.

    The power limiter is in the CDI, the engine itself is capable of (cough) 1.3Kw or so - use a pitbike cdi... Mucho power (well, compared to what it was).
     
  10. BoltsMissing

    BoltsMissing Active Member

    Thanks
    Any pitbike cdi or a specific CDI ? do you have a part number ?

    I've drilled some extra "breath" holes where the air filter sits, slight increase in revs.
     
  11. heathyoung

    heathyoung Member

    They are a reasonably generic CDI, I'm trying to remember how it works again - I'm pretty sure its a rev limiter as the CDI is different for the US market. Its a 3 wire jobbie IIRC, with a separate ignition coil. Silicon chip published a static advance CDI schematic ages ago, I have a subscription so I should be able to dig it up for you.

    The pitbike ones are often a 3 wire with some advance integrated into them, so you could push a bit more out of it.
     
  12. BoltsMissing

    BoltsMissing Active Member

    If I remember rightly, ( can't find the documentation for now ) the rev limitation is caused by making it 4-stroke or even 6-stroke.
    Meaning, making it fire every 4th or 6th stroke if the revs. reach a certain limit.
    Can that barrier be removed ?
     
  13. rooooboy

    rooooboy New Member


    I am willing to try and change the CDI, i took the bike for a road test last weekend and it ws severly underpowered, up a hill, compared to my Grubee 66c. i feel it may well be in the centrufugal clutch, but ptretty much anyhill it felt like th emotor wasnt doing anything.

    it def runs a lot quiter than myu grubee! pity though because the bike is cery comfy! just needs more balls! hahahaha
     
  14. loquin

    loquin Active Member

    I've read that the CDI is what causes it to stop firing on every cycle. IF you can replace the CDI with one without the RPM limit...
     
  15. heathyoung

    heathyoung Member

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