09 zx6r bogging down at high rpms - ZX6R Forum
 
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post #1 of 13 Old 05-18-2017, 01:18 AM Thread Starter
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09 zx6r bogging down at high rpms

Here's the story.

Bike gets to roughly 10k rpm and bogs down, stutters and won't go any higher, no matter the situation.

I have just replaced the fuel pump and fuel filter as they were my first thoughts but still no luck.

The bike is completely stock except for a power commander.

I have a suspicion that the butterfly valve in the stock exhaust is not opening but I can physically see throttle adjusting the valve on the outside.
One other thing that also makes me curious is that i bought the bike with an m4 pipe on it but never rode it quick as i was learning the bike still so i never noticed the high rpm issue, then I changed it back to stock for legal reasons. I did notice though that there was no f.i light on the dash which i've read will come up if you remove the stock exhaust and replace with an aftermarket one so that has also made me suspicious.

I'm looking for ideas or guidance on what to do next that could resolve the issue. I was thinking of putting the m4 pipe on and seeing how it goes with that on it, and then maybe disconnecting the power commander.

Any help would be greatly appreciated!
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post #2 of 13 Old 05-18-2017, 01:57 AM
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Disconnecting that power commander was the first thing u shouldve done. I bet thats your problem.....mate!
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post #3 of 13 Old 05-18-2017, 03:43 AM
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^the PC is an easy check, to see if it is related.

The butterfly in the exhaust is only constricting the pipe around the mid RPM point, for EPA mandated noise control. It's open at low and high RPM.

If you are concerned that it's the issue, you could remove the cables from the servo. That disables it 'open', but keeps the fault codes from showing up.

"Basic stuff fellas. Use your head for something other than to break your next fall."

"There's this adage that we have 2 ears and one mouth so we should listen twice as much as we talk. Unfortunately with the Internet people have taken this old adage and turned it around. They have two eyes and 10 fingers so they think they need to post 5 times as much as they read. And since they have 10 fingers and one brain, they only have to think 10% of the time! "
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post #4 of 13 Old 05-18-2017, 09:21 PM Thread Starter
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Originally Posted by Scorpi0 View Post
Disconnecting that power commander was the first thing u shouldve done. I bet thats your problem.....mate!
I think the power commander will be my next point of contact. I can't even check what fuel map, if any, is loaded onto it as i have a mac fml

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Originally Posted by RJ2112 View Post
^the PC is an easy check, to see if it is related.

The butterfly in the exhaust is only constricting the pipe around the mid RPM point, for EPA mandated noise control. It's open at low and high RPM.

If you are concerned that it's the issue, you could remove the cables from the servo. That disables it 'open', but keeps the fault codes from showing up.
I might give this a shot too! Thanks for the thought
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post #5 of 13 Old 05-19-2017, 07:52 PM Thread Starter
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So i took the easier option of disconnecting the cables that are connected to the servo underneath the seat, just undid them and let them sit there and the bike ran at 100%

Now comes the dummy part, i don't want to just leave them hanging there as i'm selling the bike soon and want it all done properly so is this a servo motor issue that needs replacement or...?

Honestly stunned me at the power it actually has for 600
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post #6 of 13 Old 05-20-2017, 03:01 AM
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Originally Posted by 4htrs View Post
So i took the easier option of disconnecting the cables that are connected to the servo underneath the seat, just undid them and let them sit there and the bike ran at 100%

Now comes the dummy part, i don't want to just leave them hanging there as i'm selling the bike soon and want it all done properly so is this a servo motor issue that needs replacement or...?

Honestly stunned me at the power it actually has for 600
It may sound like a silly question, but which end of the cables did you disconnect? Mine have been hanging loose under the seat at the servo, for at least two years without causing any issues. As I have to think this is where you made the break, I have to wonder if the servo was ever working -- presumably you have heard the servo cycle through it's range whenever you turn the ignition on? Have you observed it actually rotating, pulling and pushing the cables?

"Basic stuff fellas. Use your head for something other than to break your next fall."

"There's this adage that we have 2 ears and one mouth so we should listen twice as much as we talk. Unfortunately with the Internet people have taken this old adage and turned it around. They have two eyes and 10 fingers so they think they need to post 5 times as much as they read. And since they have 10 fingers and one brain, they only have to think 10% of the time! "
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post #7 of 13 Old 05-20-2017, 04:20 AM Thread Starter
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Originally Posted by RJ2112 View Post
It may sound like a silly question, but which end of the cables did you disconnect? Mine have been hanging loose under the seat at the servo, for at least two years without causing any issues. As I have to think this is where you made the break, I have to wonder if the servo was ever working -- presumably you have heard the servo cycle through it's range whenever you turn the ignition on? Have you observed it actually rotating, pulling and pushing the cables?
I disconnected the cables from the motor underneath the seat.
Yeah I have heard/seen the servo function when turning the ignition on and also whilst giving it throttle whilst on the paddock stand which is making me wonder, can these malfunction? And is it worth just leaving the cables loose under the seat?
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post #8 of 13 Old 05-20-2017, 04:40 AM
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The servo system is purely meant to decrease noise during EPA mandated testing. The ball valve in the exhaust, which is built into the OEM muffler assembly makes the pipe diameter smaller at mid RPM. That increased back pressure reduces the amount of sound coming through to the final muffler stage. The valve is spring loaded, and is supposed to be wide open at both low and high RPM...... it's meant to only restrict the flow, around the RPM the EPA measures the noise at (50% max RPM).

If it runs better with the cables disconnected, I have to wonder if the mechanism switching the ball valve in is gummed up. I know it's a push-pull cable system, but there is a pretty hefty spring that assists the motion mounted on the can. At least on the OEM set up. If you have an after market can with an alternate valve system, I can't comment.

A pic of the area where the cables attach to the pipe may be helpful.

"Basic stuff fellas. Use your head for something other than to break your next fall."

"There's this adage that we have 2 ears and one mouth so we should listen twice as much as we talk. Unfortunately with the Internet people have taken this old adage and turned it around. They have two eyes and 10 fingers so they think they need to post 5 times as much as they read. And since they have 10 fingers and one brain, they only have to think 10% of the time! "
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post #9 of 13 Old 05-20-2017, 05:27 AM Thread Starter
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Originally Posted by RJ2112 View Post
The servo system is purely meant to decrease noise during EPA mandated testing. The ball valve in the exhaust, which is built into the OEM muffler assembly makes the pipe diameter smaller at mid RPM. That increased back pressure reduces the amount of sound coming through to the final muffler stage. The valve is spring loaded, and is supposed to be wide open at both low and high RPM...... it's meant to only restrict the flow, around the RPM the EPA measures the noise at (50% max RPM).

If it runs better with the cables disconnected, I have to wonder if the mechanism switching the ball valve in is gummed up. I know it's a push-pull cable system, but there is a pretty hefty spring that assists the motion mounted on the can. At least on the OEM set up. If you have an after market can with an alternate valve system, I can't comment.

A pic of the area where the cables attach to the pipe may be helpful.
It is the factory OEM exhaust.
I will get a picture soon and post one up
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post #10 of 13 Old 05-20-2017, 06:02 AM
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^^ I know what the OEM setup looks like. Same as what is on my bike.

"Basic stuff fellas. Use your head for something other than to break your next fall."

"There's this adage that we have 2 ears and one mouth so we should listen twice as much as we talk. Unfortunately with the Internet people have taken this old adage and turned it around. They have two eyes and 10 fingers so they think they need to post 5 times as much as they read. And since they have 10 fingers and one brain, they only have to think 10% of the time! "
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post #11 of 13 Old 05-20-2017, 06:10 AM Thread Starter
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I've added an attachment of the exhaust side of things
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post #12 of 13 Old 05-20-2017, 12:57 PM
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The spring holds the valve all the way open when the cables are not attached to the servo. Were it me, wanting to sell on the bike, I would remove the cables altogether and leave it 'defaulted' to wide open.

"Basic stuff fellas. Use your head for something other than to break your next fall."

"There's this adage that we have 2 ears and one mouth so we should listen twice as much as we talk. Unfortunately with the Internet people have taken this old adage and turned it around. They have two eyes and 10 fingers so they think they need to post 5 times as much as they read. And since they have 10 fingers and one brain, they only have to think 10% of the time! "
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post #13 of 13 Old 05-20-2017, 05:15 PM Thread Starter
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Originally Posted by RJ2112 View Post
The spring holds the valve all the way open when the cables are not attached to the servo. Were it me, wanting to sell on the bike, I would remove the cables altogether and leave it 'defaulted' to wide open.
i think that may be the way to go! seems like the easiest and most logical decision.

happy that i solved the issue regardless, thanks !
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