Author Topic: Main jet question  (Read 422 times)

Offline Gusable

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Main jet question
« on: November 28, 2022, 08:02:46 PM »
So my 94 cali 1100 is running really good and Iím very happy with it. (Phf36ís) That being said the tune right now is 60 pilot, AB268 atomizer, K5 needle on second notch and 145 main jet. That 145 is what was in it when I got it. From what I know it should have come with a 130 main stock.  If my math is right the 145 is only about 11% more fuel.  The fuel mileage is what Iím trying to improve. Itís about 30.5-34.5mpg at this time with 7/33 axle. Accelerator pump tuning is something Iíd like to do as well.  So that main jet is in play at 4000rpm yes? I think thatís about 1/2 throttle.  Thank you
« Last Edit: November 28, 2022, 08:05:32 PM by Gusable »
1994 California 1100

Offline Gusable

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Re: Main jet question
« Reply #1 on: November 28, 2022, 08:04:34 PM »
The chart



1994 California 1100

Offline guzzisteve

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Re: Main jet question
« Reply #2 on: November 28, 2022, 08:55:32 PM »
Mark the switch w/tape every 1/4 throttle, then on bottom 1/8 throttle. Put tape on grip to correspond with marks on switch.
Amazing, you'll see you will be at 1/8 throttle in high gear NOT half. This at a steady throttle once at 4Krpm.
You won't know unless you mark the throttle, you'll only assume you are correct
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Re: Main jet question
« Reply #3 on: November 28, 2022, 10:08:59 PM »
The previous two posts have it right, I believe. But a minor correction on your calculation of the difference in flow between a 145 and a 130 main jet. The flow varies with the area instead of the diameter of the opening, so the ratio is 145 squared over 130 squared, which works out to a 24% increase instead of an 11% increase. (The other terms for the area of a circle cancel out between the numerator and denominator.)
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Re: Main jet question
« Reply #3 on: November 28, 2022, 10:08:59 PM »

Offline Gusable

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Re: Main jet question
« Reply #4 on: November 28, 2022, 10:35:58 PM »
Thank you for that mathematical correction. Thatís the real numbers I was looking for.  If I could take 20% out of that main Iíd like to try that.  Thank you!
1994 California 1100

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Re: Main jet question
« Reply #5 on: November 28, 2022, 10:54:13 PM »
Thank you for that mathematical correction. Thatís the real numbers I was looking for.  If I could take 20% out of that main Iíd like to try that.  Thank you!
You're welcome, of course. You have the jet you want in your hand so to speak. Since the flow of the 145 jet is about 24% greater than the 130 jet, it's also true that the 130 jet flows about 20% less the 145. That is, (145^2)/(130^2) ~= 1.244, while (130^2)/(145^2) ~= 0.804.

Even though the main jet doesn't have much effect at the quarter or so throttle you will be using during cruising, I would certainly recommend going back to the stock main jet as your first step. Many riders go up too far on the main jet trying to correct other perceived problems in their setups.
« Last Edit: November 28, 2022, 11:02:52 PM by moto »
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Offline moto-uno

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Re: Main jet question
« Reply #6 on: November 28, 2022, 11:29:15 PM »
 Your main jet isn't of any consequence with your highway mileage concerns !
 Your idle jet (and it's adjustment screw) , throttle slide #( cut away ) and needle jet and needle position are
 all involved and over lapping at your highway speeds , and , this is also kinda important ,
 make sure your needle and needle jet are not suffering from high mileage wear .  Peter

Offline Gusable

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Re: Main jet question
« Reply #7 on: November 28, 2022, 11:36:32 PM »
Pilot,needle and atomizer are all brand new.  I wish I could run less pilot but it just does NOT like anything but that 60. Anything less and it lean pops/stumbles.  Runs and idles great with it.  I shorted my factory long screws to .100 but have a new set of longs I can try. I think maybe the long tip will give a better signal through that circuit
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Offline Gusable

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Re: Main jet question
« Reply #8 on: December 04, 2022, 04:18:55 PM »
Major update! I got a cyber Monday deal on a quick detach phone mount and using a GPS speedo app I calculated the REAL trip miles on this bike. My speedo is dead nuts accurate. 7/33 in back, they must have done the trans gear too!  Trip meter is slow though. Said I went 27 miles really went 31 ish!!  End result is 43MPg!!! Iím so happy.  I did order a set of 130 mains. Next time I go in there Iíll install them and put the leaner AR268 atomizers in there

« Last Edit: December 04, 2022, 04:51:11 PM by Gusable »
1994 California 1100

Offline Wayne Orwig

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Re: Main jet question
« Reply #9 on: December 04, 2022, 07:23:17 PM »
 :thumb:
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Re: Main jet question
« Reply #10 on: December 06, 2022, 07:36:50 AM »
Main jet is set for WFO. For mid range you adjust the needle and needle jet. I tuned my 850 LeMans at the drag strip. Stock 135 main was replaced with a 143 and a result of 10mph greater top end. Ethanol fuel runs leaner. It takes X amount of horsepower to go a certain speed, not a particular throttle position. If you arenít feeding it enough energy you just have twist the throttle further. Changing main jets is just false economy.

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Offline Gusable

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Re: Main jet question
« Reply #11 on: December 06, 2022, 10:28:08 AM »
Iím keeping the 145ís for now. 43mpg Iím thrilled!
1994 California 1100

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