Anyone running 38 pilots with ear shave? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 17 (permalink) Old 06-24-2011, 12:46 AM Thread Starter
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Question Anyone running 38 pilots with ear shave?

I just started putting everything together after an extensive engine rebuild and realized the dealer gave me the wrong pilots so the only ones I have are the original size 38 jets. I want to finish tomorrow and put the jets in when i get them but i was wondering how the bike will run with smaller pilots. Do i need to wait or will the bike run? I'm doing the ear shave and coasters on a 94 750 vulcan in conjunction with the rebuild. I have the 140 mains and 2 shims on the needle. Also, what would you guys suggest to set my mixture screws to? Thanks
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post #2 of 17 (permalink) Old 06-24-2011, 08:29 AM
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I just started putting everything together after an extensive engine rebuild and realized the dealer gave me the wrong pilots so the only ones I have are the original size 38 jets. I want to finish tomorrow and put the jets in when i get them but i was wondering how the bike will run with smaller pilots. Do i need to wait or will the bike run? I'm doing the ear shave and coasters on a 94 750 vulcan in conjunction with the rebuild. I have the 140 mains and 2 shims on the needle. Also, what would you guys suggest to set my mixture screws to? Thanks
What exhaust system are you using? The stock main is 132 so you might be running rich. You are only using the pilots to about 3000 rpm.

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post #3 of 17 (permalink) Old 06-24-2011, 09:28 AM Thread Starter
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Ive got the cobra slash cuts on it.
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post #4 of 17 (permalink) Old 06-24-2011, 09:59 AM
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Ive got the cobra slash cuts on it.
My opinion is and others can disagree-- Stock jet 132, add for pipes and ear shave brings you to 135-138 main jet, subtract one size for your sea level ( I believe around 2000 feet ) brings you back down to 135. JMO

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" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
iridiums
decals removed
upgraded mirrors
Pic up coil mod done
degoated
All LED lighting
Upgraded Mosfet rectifier
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post #5 of 17 (permalink) Old 06-24-2011, 10:27 AM
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What exhaust system are you using? The stock main is 132 so you might be running rich. You are only using the pilots to about 3000 rpm.
I think it is more accurate to say only the pilots are working up to 3,000 rpm.
If I understand the carb operation correctly, the pilot jets continue to feed fuel into the mix at all times, even though the main jets provide the majority of the fuel at higher rpms.

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post #6 of 17 (permalink) Old 06-24-2011, 10:38 AM
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I think it is more accurate to say only the pilots are working up to 3,000 rpm.
If I understand the carb operation correctly, the pilot jets continue to feed fuel into the mix at all times, even though the main jets provide the majority of the fuel at higher rpms.
LOL I fail to see the difference.

JM2001

" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
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decals removed
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Pic up coil mod done
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All LED lighting
Upgraded Mosfet rectifier
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post #7 of 17 (permalink) Old 06-24-2011, 10:56 AM
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I actually ran stock pilot jets with an earshave and Jardine rumblers,150in the back cylinder and 148 main on the front ,two and a half +/- on the airscrews with no shims on the needle and the pickup coils set at.018 at about 800 feet above sea level.I just messed with mine till it ran like I wanted , I had a kit with several different mainjets in it.I have found there are no hard and fast rules as each engine will respond differently to the same changes ,the charts are a good starting point to fine tune from.




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post #8 of 17 (permalink) Old 06-24-2011, 12:34 PM
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I actually ran stock pilot jets with an earshave and Jardine rumblers,150in the back cylinder and 148 main on the front ,two and a half +/- on the airscrews with no shims on the needle and the pickup coils set at.018 at about 800 feet above sea level.I just messed with mine till it ran like I wanted , I had a kit with several different mainjets in it.I have found there are no hard and fast rules as each engine will respond differently to the same changes ,the charts are a good starting point to fine tune from.
Denny, Obviously you know what you are doing. Help me make more sense out of this. Most mods I have seen on this forum relate to performance exhaust and ear shave mods. One reduces back pressure, one increases air flow. Neither one has a MAJOR effect. No one has increased compression, changed cam profile, bored out the cylinders, or done anything else which would require a drastic increase in fuel flow over the stock requirement. Starting with a base of 132 main jet, I have seen sizes used from 135- 150. I am trying to figure out where or why this much fuel increase is needed. Based on our 750 cc and compression I just don't see where the need is justified.

JM2001

" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
iridiums
decals removed
upgraded mirrors
Pic up coil mod done
degoated
All LED lighting
Upgraded Mosfet rectifier
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post #9 of 17 (permalink) Old 06-24-2011, 12:59 PM
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I live at 5280 Im running mine with a 135 main, fac pro needles raised all the way 5th clip, and my pilots are what were in it orig. I think they are 38 but havent checked. I know Im still a little lean so I have to pull my carbs again. The bike will run if the pilots are a bit to small but low end will be flat and exhaust will pop. Im thinking he should be at 40 pilot and 138 main heres why. The aftermarket pipes change back pressure so at sea level for the pipe change you should go from 132 to 135. Because of the ear shave hes getting more air which requires more fuel to correct the mix. so the pilot again goes up one step so 138-140 depending on the bike. The stock pilots will allow her to run but your air fuel screws will have to be out a ways and shell be lean still. so eventually you and I need to up the pilots. Right now my bike is flat in the low rpms 1/4 throttle because I never upped my pilot when I did my shave.

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post #10 of 17 (permalink) Old 06-24-2011, 01:08 PM
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Quote:
Originally Posted by JM2001 View Post
Denny, Obviously you know what you are doing. Help me make more sense out of this. Most mods I have seen on this forum relate to performance exhaust and ear shave mods. One reduces back pressure, one increases air flow. Neither one has a MAJOR effect. No one has increased compression, changed cam profile, bored out the cylinders, or done anything else which would require a drastic increase in fuel flow over the stock requirement. Starting with a base of 132 main jet, I have seen sizes used from 135- 150. I am trying to figure out where or why this much fuel increase is needed. Based on our 750 cc and compression I just don't see where the need is justified.
An engine is basically a self powered air pump,the more air and fuel you can pass thru an engine along with as near as you can get to complete combustion of said fuel mixture,the more power an engine of a given size will make.

The earshave allows a less restrictive intake letting more air into the engine the jets are increased in size to compensate fuel mixture for the added air.

A freer flowing exhaust lets the burned A/F mixture flow out more efficently.


Now, all the fuel and the air in the world is not going to do you any good if it is not burning efficently,this is where the regapping the pickup coils helps. The rotor for the stator has a permanent magnet that turns by the stastionary pickup coils are and when the coils pass through the magnetic field there is a voltage induced into the coils that travels to the ignitor to trigrer it to fire the coils,the ignitor actually turns power on and off the Ignition coils which are basically transformers that take battery voltage and step it up to the higher voltages needed to fire the spark plugs when the ignitor turns of the primary voltace and the magnetic fields collapse and discharge a higher votage from the seconday coils to the plugs.

The pickup coils position in the magnetic field relative to the permanent magnet (closer to the rotor or farther)determines when and how long the ignitor is sending voltage to the ignitor affecting both ignition timing and dwell.

It seems to me that the timing is advanced a small amount and it stays in the field longer when regapped giving a nice fat spark to burn all the fuel and air we are passing through the engine,Iridium plugs also help here too, if for no other reason than they remain at original gap for a long time and the fine electrode seems to help too.

Sorry for bring so lengthy but you asked,I can't believe I typed all that out,shew I hope it helps you understand why we do the things we do ,a little better.




If you see it on my bike I did it
VROC#30324
92 vn750(sold)
Current ride 05 1500 Classic FI
lovin' the new scoot



Quote:
"When all is said and done,usually more is said than done" UNK
Click on one x and drag to the other to read between them.

Psalm 40:1...
XI waited patiently for the Lord; and he turned unto me, and heard my cry. X
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