Changing Fuel / Oil ratio instead of Jet's !?

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Oldschool
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Changing Fuel / Oil ratio instead of Jet's !?

Post by Oldschool »

Talk about Lazy...!
I'm jetted for 60 degree weather 152/42 RB'ed
and the weather outside is 40's all week
Can I go to 42:1 from 50:1 to richen things up?

Have you ever heard of such an idea?
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kawagumby
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Post by kawagumby »

Yeah, I've tried it myself. It does work, but is kind of imprecise/ trial and error. But, what the hey, for lazy guys like us it is better than tearing apart a carb. :mrgreen:
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Post by j753301 »

im not sure how wrong i am but this sounds like you may be compromising the motor for being lazy.im lazy too,lol, but wouldnt want to shorten the life of my motor.
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Post by kawagumby »

You won't compromise anything as long as you stay within the premix manufacturer's spec's and have an experienced feel for power and an ear for pinging, eh?
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canyncarvr
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Post by canyncarvr »

Figure out the volume of fuel difference between 42/50:1 and you get a very little number. Hard to compare to what the volume of delivery is with a different sized hole in your jet..but doubtfully as much. There's a thread here about that...but I'm too lazy to go looking for it. :wink:

Yes, it changes the air/fuel ratio, but not as much as a jetting change will/does.

If the main is what you're changing with temp changes (probably), access it through the access cover on the bottom of the bowl. No need to take anything apart.

That said I generally do change pilots as seasons come and go. ...need a bigger access cover for that!

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Post by skipro3 »

Bear in mind that not only ll the ratio affect the jetting but that the oil you use to make that change will also affect it by the oil's viscosity. A Thicker oil will slow down the to volume of mix flowing through a fixed jet size. Instead of adding more 2 stroke oil, , keep that ratio constant and add 80 wt gear oil to thicken up the fuel and there-by lean out the "Jetting. ".
Let me know if it works :lol:
Jerry

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Post by canyncarvr »

Which cSt rating @ 40ºC of SAE J306 rated viscosity oil would you suggest?

Yes. I am glad I could help. :roll:

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