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 Stock Jet size?
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Joined: Feb 2006
Posts: 1,690
Learned Hand
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OP
Learned Hand
Joined: Feb 2006
Posts: 1,690 |
Thinking maybe a larger jet may help the performance of my 2005 America. Right now, at cruise (5th gear and 75 mph) It feels like someone stepping down on the brake pedal. Not sure if it's running lean or rich.....Stock pipes, with 3 stages removed, everything else completely stock. Did it come with 42 size jets? I'll order the 45's and see if it helps. About ready to just buy a new Thunderbird...
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Re: Stock Jet size?
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Joined: Jun 2011
Posts: 407 Likes: 2
Adjunct
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Adjunct
Joined: Jun 2011
Posts: 407 Likes: 2 |
More experienced operators here may chime in. Changes to allow more air flow from the exhaust usually also results in the need to change the main jet. Doubt your pilot jet (could be 42 stock) will need changing. Could be the same or similar on our motors but on my previous Bonneville when changing to TOR mufflers the main jet went from a 110 to a 120 size if I remember correctly. There should still be a link to the jetting calculator here http://www.bonnevilleamerica.com/dinqua/friar/
Last edited by MattyMo; 02/22/2018 9:09 AM.
09 America, some modifications
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Re: Stock Jet size?
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Joined: May 2010
Posts: 5,720
Check Pants
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Check Pants
Joined: May 2010
Posts: 5,720 |
To my understanding, reducing exhaust back pressure without increasing air/fuel intake, rewards you with more noise and a reduction in available torque. If you add fuel delivery without the air to burn it, what exactly have you accomplished? A really smelly exhaust, perhaps? An easy fix is to correctly drill/modify your airbox, then you can run 132- 140 jets, restore some balance in the air/fuel/open-exhaust equation and get some of the latent power available.
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Re: Stock Jet size?
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Joined: Feb 2007
Posts: 23,243 Likes: 64
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,243 Likes: 64 |
The question should be approached a little differently than the previous 2 answers. You can not just toss out a generic one size fits all jetting answer. You have to figure in your altitude above sea level and average humidity as well as any exhaust or intake changes to get correct jetting. For instance where Ryk is his sizes may be correct but for where I live with pods and open exhaust my main is 155 and my pilot is 48 and that was tuned on a dyno with an exhaust sniffer. Reducing back pressure does not reduce torque unless you pass a certain threshhold. You want good flow with some back pressure. ( the actual best I have seen is with an adjustable baffle in a super trap with pod intake filters with the baffle adusted on a dyno) Depending how deep you want to get there are other changes you can make to the stock carbs to gain better performance like drilling the air bleed hole and changing slide springs and needles and needle position, etc....
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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