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Author Topic: Jeting 550 to match filter/exhaust  (Read 942 times)

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greatpenguin

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Jeting 550 to match filter/exhaust
« on: July 27, 2009, 07:55:11 AM »
Ive just got a 74 550 and tore the carbs apart because one of the floats were stuck.  When inside I saw that its still running 100mains and 38slow jets.  From what ive read up, these are basically stock.  The bike has Individual UNI foam filers, and a low restriction 4-1 exhaust.  I after a cleaning of the carbs, adjusting the points, cleaning plugs it has hesitation at very low throttle, and hesitation in High throttle.

I was looking through the FAQ and tried the search but failed.  Im sure there is a huge knowledge base on here that I just couldn't find.  If someone could point me in the right direction, or offer some suggestions about what jets I should try to help the mixture I would appreciate it.  Thanks!
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Offline Laminar

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Re: Jeting 550 to match filter/exhaust
« Reply #1 on: July 27, 2009, 08:19:43 AM »
105-110 mains should work well with stock idle jets and air screws adjusted correctly.
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Offline Cvillechopper

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Re: Jeting 550 to match filter/exhaust
« Reply #2 on: July 27, 2009, 08:20:46 AM »
You were in the right area.  Read the carb FAQ a few times.  It will walk you through the basics of diagnosis and correction of carb jetting.  Very basically, do a plug chop at WOT, take some pics and post them.  The plugs will tell you which way to adjust the main jets (re-jet).  Once that is corrected you can move to the needle settings, then the idle circuit.  

There is very details information in the FAQ section and it may seem overwhelming.  That's why I say read it a few times.  you'll pick up something new each time.

Good luck
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Offline Celco

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Re: Jeting 550 to match filter/exhaust
« Reply #3 on: July 27, 2009, 04:37:42 PM »
Where would this carb FAQ be? I am going to be tinkering with this soon myself too I believe.
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Offline Cvillechopper

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Re: Jeting 550 to match filter/exhaust
« Reply #4 on: July 27, 2009, 04:50:35 PM »
Quote from: Celco on July 27, 2009, 04:37:42 PM
Where would this carb FAQ be? I am going to be tinkering with this soon myself too I believe.

On the main page of the forums there is a section named FAQ.  Under there you'll find several threads.  One is called Carb FAQs.
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Offline Porscheguy912

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Re: Jeting 550 to match filter/exhaust
« Reply #5 on: July 27, 2009, 09:42:18 PM »
Quote from: greatpenguin on July 27, 2009, 07:55:11 AM
Ive just got a 74 550 and tore the carbs apart because one of the floats were stuck.  When inside I saw that its still running 100mains and 38slow jets.  From what ive read up, these are basically stock.  The bike has Individual UNI foam filers, and a low restriction 4-1 exhaust.  I after a cleaning of the carbs, adjusting the points, cleaning plugs it has hesitation at very low throttle, and hesitation in High throttle.

I was looking through the FAQ and tried the search but failed.  Im sure there is a huge knowledge base on here that I just couldn't find.  If someone could point me in the right direction, or offer some suggestions about what jets I should try to help the mixture I would appreciate it.  Thanks!

Welcome to the forum!
I had the same bike a few years ago and went through the same issues. Check my posts from 2 years ago and you'll find some good info from me and others.
(I ran open pipe 4-1 pods and 120 mains) It was fast as $hit  ;D
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Offline Flying J

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Re: Jeting 550 to match filter/exhaust
« Reply #6 on: July 31, 2009, 09:55:14 AM »
Did you move the needle up at all? I have the same setup 4-1 and foam. I have 110 mains and was wondering if i need to raise the needle.
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Offline Aaron Richard

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Re: Jeting 550 to match filter/exhaust
« Reply #7 on: July 31, 2009, 10:01:47 AM »
105-110's are good sizes to use, #40 slow jets smooth the idle out a bit also. 3-4 clip setting on needle.
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