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FJR Motorcycle Forums
Technical & Mechanical Problems
Stuttering problem, I'm at a loss (Update, Problem Fixed)
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<blockquote data-quote="ionbeam" data-source="post: 1231617" data-attributes="member: 277"><p>A clogged cat (!) will cause power loss at higher RPM but not a rough engine and it will not change with engine temperature.</p><p></p><p>It is telling that the header temperatures are different with the two inside pipes appearing hotter. Could be fueling, could be spark. It is notable, as you noted, <img src="https://www.fjrforum.com/forum//public/style_emoticons/default/smile.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /> that cyls 1 & 4 don't glow the headers and are sparked by the same coil. Sometimes life likes to goof on ya and throw in what looks like a sure thing only to have something else quite less likely to be the real root cause.</p><p></p><p>I think it is a great idea to take the aftermarket fuel trim unit out of the picture before going on with other ideas.</p><p></p><p>As always, change just one thing at a time, measure/note/confirm any changes and <em>then</em> move on to the next item.</p><p></p><p>I assume that the engine was not completely up to operating temperature or perhaps the battery wasn't fully charged when the compression check was done.</p></blockquote><p></p>
[QUOTE="ionbeam, post: 1231617, member: 277"] A clogged cat (!) will cause power loss at higher RPM but not a rough engine and it will not change with engine temperature. It is telling that the header temperatures are different with the two inside pipes appearing hotter. Could be fueling, could be spark. It is notable, as you noted, [IMG]https://www.fjrforum.com/forum//public/style_emoticons/default/smile.png[/IMG] that cyls 1 & 4 don't glow the headers and are sparked by the same coil. Sometimes life likes to goof on ya and throw in what looks like a sure thing only to have something else quite less likely to be the real root cause. I think it is a great idea to take the aftermarket fuel trim unit out of the picture before going on with other ideas. As always, change just one thing at a time, measure/note/confirm any changes and [I]then[/I] move on to the next item. I assume that the engine was not completely up to operating temperature or perhaps the battery wasn't fully charged when the compression check was done. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Stuttering problem, I'm at a loss (Update, Problem Fixed)
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