CBR 900RR Mystery Sickness
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some other thoughts. has stock 900rr some heat shields between engine, filter box, carbs? maybe this is removed? than one ktm had problem fuel line was too close to engine and when engine warmed up bike started bogging because fuel start to bubble. but what about rpms near to red line? is engine there running clean?
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ok I believe I found the culprit...Drum roll please.........
Ignition coils.
I will be ordering them tomorrow to make sure that it is indeed the culprit,but when I stumbled across "ignition coil failure symptom" it was like they were describing my exact problem,110%.everything down to the smallest detail was on the money.I am so sure that this is it.heres the thing,is a symptom of coil failure is that it will improve dramaticlly when plugs are replaced,but within a couple hundred miles,it returns when the plugs are fouled again.The plugs were replaced the same time as the jet kit was installed(because they were fouled,so I thought the improvement was because of jetkit),thus improving the symptoms...the symptoms are back,so i guess I need to replace plugs,and replace coils,kiss her softly on the gas tank,and keep my fingers crossed...thanks to everyone who helped and I will keep you posted as to whether I am right,or just being optimistic
Ignition coils.
I will be ordering them tomorrow to make sure that it is indeed the culprit,but when I stumbled across "ignition coil failure symptom" it was like they were describing my exact problem,110%.everything down to the smallest detail was on the money.I am so sure that this is it.heres the thing,is a symptom of coil failure is that it will improve dramaticlly when plugs are replaced,but within a couple hundred miles,it returns when the plugs are fouled again.The plugs were replaced the same time as the jet kit was installed(because they were fouled,so I thought the improvement was because of jetkit),thus improving the symptoms...the symptoms are back,so i guess I need to replace plugs,and replace coils,kiss her softly on the gas tank,and keep my fingers crossed...thanks to everyone who helped and I will keep you posted as to whether I am right,or just being optimistic
Last edited by the cyclops; Mar 9, 2010 at 01:45 AM.
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Joined: Apr 2008
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From: Northern Michigan
One thing you should check as well is to see if the problem is throttle position dependant, or actual rpm dependant. Many times, they can be confused. For example, around 1/8 throttle, the main jet is starting to take over from the pilot jet within the carb. This usually occurs around 3000 rpms. If you have pilot jets that are not adjusted properly, or gummed up, then can cause this type of issue. I know you mentioned the carbs were cleaned. But I've seen carbs that were cleaned at shops and the pilot jets were never taken out. For some reason, many people don't remove them and clean them. they just clean the float bowl and main jet.
the dirtier they get, the higher in the throttle range the problem can occur.
I'm not sure I would lean towards the coils. usually, bad coils will fail at higher rpms and run ok at lower rpms. But thats not a given, just what I've seen from them. also, you should be able to check the ones you have with an ohm meter. As long as the coil is measuring the correct resistance, it should be ok.
the dirtier they get, the higher in the throttle range the problem can occur.
I'm not sure I would lean towards the coils. usually, bad coils will fail at higher rpms and run ok at lower rpms. But thats not a given, just what I've seen from them. also, you should be able to check the ones you have with an ohm meter. As long as the coil is measuring the correct resistance, it should be ok.
Last edited by justasquid; Mar 13, 2010 at 06:12 AM.
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