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Post by flqu06 on Apr 19, 2014 16:26:29 GMT -5
Does that mean its lean at 70?
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Post by 90GTVert on Apr 19, 2014 17:24:40 GMT -5
The tune is more rich at 70 degrees and leaner at 50 degrees, if all else is equal. Colder air is more dense. So running better at 50 would more likely mean it likes a leaner mixture than it's getting at 70. Pay attention to humidity too if you are going to use the weather to tune. More humid air is less dense. Don't worry about small swings though.
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Post by flqu06 on Apr 19, 2014 20:04:55 GMT -5
Huh. I put in an 80 and it doesnt run as well warm as the 85...do i need to put in a 88?
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Post by Upgrayedd on Apr 19, 2014 20:08:45 GMT -5
Runs Leaner / Cold Weather <-----{Same Jet+Same Airbox Setup}-----> Hot Weather / Runs Richer
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Post by Upgrayedd on Apr 19, 2014 20:14:12 GMT -5
Huh. I put in an 80 and it doesnt run as well warm as the 85...do i need to put in a 88? if she's running better with an 85 main when its cold out vs warm, i would be inclined to think either stepping down to an 82, or opening up your air intake a little bit (both would lean the mix out a little) might get you closer to where you want to be. i might be completely misunderstanding you :/ but i think i follow ya. |
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Post by flqu06 on Apr 19, 2014 20:31:39 GMT -5
To clarify. Remember I don't have a choke anymore so I'm not getting that extra fuel. In the mornings when it's cooler it will hesitate a bit till the scoot warms up which is understandable. But after it's warm it runs great. In the afternoon when it's warmer it doesn't have the same wot performance. So I tried the 80 and it runs about the same when the scoot warm and the temp out is warm.
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Post by Upgrayedd on Apr 19, 2014 20:45:11 GMT -5
Cold air has more oxygen in it (more dense) than warm air. So it leans out the ratio when its cold compared to when its hot out. Sounds (to me) like you're running a bit more rich than needed when its hot out. Maybe not, you gotta check your plug.
There's more than one way to skin that cat. I dont like changing jets a lot, so I try and set my jetting in cooler weather, and then open up my airbox a bit for summer (to supply just a little more air since warmer air is less dense). Id rather pull a plug out of my air box, or stick it back in when it gets cold, than keep opening up a carb to fiddle with jets.
*i have a plug i pulled from my intake, i keep it in my tool pouch under the seat.
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Post by 2TDave on Apr 20, 2014 6:01:52 GMT -5
With muscle cars years ago we all knew we ran better when it was cool out. We could jet our 4 barrels for it being hotter but they still didn't make the same power. We use to chalk it up to vapor lock. The NASCAR guys know they are faster when it's cooler as well. If you have to down jet because it's hotter and your getting less oxygen then you are getting less fuel and oxygen thus making less power.
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Post by flqu06 on Apr 20, 2014 8:17:45 GMT -5
So I can assume that without a working choke to richen the mix i should expect it to be lean for the first few minutes, if it wasnt then it would be running rich when warm so its probably tuned good now.
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Post by 2TDave on Apr 20, 2014 8:29:33 GMT -5
Makes sense. I will be looking at down jetting now that the humidity is rising. I can smell it at an idle so the pilot will go down first then I'll start watching the plug.
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