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FJR Motorcycle Forums
Technical & Mechanical Problems
What's My TBS Move?
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<blockquote data-quote="Fred W" data-source="post: 1438655" data-attributes="member: 3828"><p>So, if cylinder 4 has less (lower) vacuum, that means cylinder 4 is drawing more air (not less). That means it can’t be a blocked air port on 4. It could be the other three are getting plugged up, or maybe the throttle plates on the other three are cruddy.</p><p></p><p>I would try closing all 4 air screws completely to see where everything else is. You could adjust the throttle plate linkages at idle to get them close, and then see what happens to vacuum as the throttles open. If they vary a lot as you open them then they may be dirty.</p><p> </p><p></p><p>On my old ‘05 I took the throttle bodies off for cleaning at around 75k miles and they were pretty well crudded up. Cruddy throttle plates will affect things at idle more since they are only cracked open, so any deposits represent a greater proportion of the air passage. </p><p> </p><p></p><p>Hope that is helpful.</p><p> </p></blockquote><p></p>
[QUOTE="Fred W, post: 1438655, member: 3828"] So, if cylinder 4 has less (lower) vacuum, that means cylinder 4 is drawing more air (not less). That means it can’t be a blocked air port on 4. It could be the other three are getting plugged up, or maybe the throttle plates on the other three are cruddy. I would try closing all 4 air screws completely to see where everything else is. You could adjust the throttle plate linkages at idle to get them close, and then see what happens to vacuum as the throttles open. If they vary a lot as you open them then they may be dirty. On my old ‘05 I took the throttle bodies off for cleaning at around 75k miles and they were pretty well crudded up. Cruddy throttle plates will affect things at idle more since they are only cracked open, so any deposits represent a greater proportion of the air passage. Hope that is helpful. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
What's My TBS Move?
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