Off-Idle Bog/Hesitation/Stumble: Let's figure this out with Science!

Maintenance, repair, troubleshooting, etc.
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Site Founder
Site Founder
Posts: 8399
Joined: Mon Nov 07, 2011 12:42 pm
Region or State: Rocky Mountains
Motorcycles Owned Currently: '92 XJR600, '92 Seca II
Location: Denver, CO
United States of America

Thu Jul 13, 2017 10:44 am

Some observations while doing this:

The engine will not idle smoothly until the pilot jets are set consistently at a particular A/F ratio. Setting all carbs to 14.7 results in a very smooth idle.

Changing pilot jets independently from this setting will cause the idle to roughen out again. But changing all pilot screws the same amount, consistently, does not impact idle.

The pilot screws are much more tunable as they are screwed out further. In the 1-3 turn band, small adjustments in the pilot screw results in wide changes to the A/F. That is, a 1/16 turn in the screw might result in an A/F moving from 16.6 to 12.1. However, after about 3 turns out, the screws can be easily adjusted to meet a certain A/F ratio.

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Almost as Awesome as Murdock
Almost as Awesome as Murdock
Posts: 2331
Joined: Sun Feb 26, 2012 2:16 am
Region or State: Motor City (MI)
Motorcycles Owned Currently: 1994 XJ600, 2006 SV650

Thu Jul 13, 2017 11:27 am

That is good to know. Interested that the suggestion was to go to 2.5 turns out instead of something a bit of 3.
Men do not quit playing because they grow old; they grow old because they quit playing.

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Lookin' Around
Lookin' Around
Posts: 40
Joined: Sun Mar 02, 2014 1:57 pm
Region or State: europe
Motorcycles Owned Currently: xj600s

Tue Sep 19, 2017 3:17 pm

hi Radare,

do you still have with these setting the 4,5k rpm buzz?


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