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Can anyone explain to me why my injectors are running at 100% duty cycle at 4K-5K RPM's. I have no big bore kit, no head work. Mods are Speedstar Stacks, PCS Monster Pro-Pipe dyna coils and wires. Got lots of air, no more fuel to match it, PCIII is maxed out in that RPM area. AFR graph goes straight to sh!t and lean at 4k onward. I thought the injectors were good till 100+hp im not even close, unless that 100+hp is at the engine not the wheel. I only have 7k miles on the bike. Can they be shot already? Need some advice please.
 

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I have no mechanical expertise...so take this for what its worth, but my Yamaha EFI 250 hp outboard recently was having a fueling isuue at high load and rpm's. I looked everywhere to trace the problem from the pick- up tube in the gas tank, through all the fuel filters, fuel lines, low pressure pumps, vapor separator tank...everything checked out, but I was still experiencing the uneven fueling at high rpm and load( ran fine in neutral). A Yamaha mechanic, who is a friend of mine, came over and pulled the filters inside the injectors...problem solved. The service manual schematic does not show this part, but the injector can be pulled apart and a small plastic ring is visible which can be pried or pulled out. This filter is shaped like a long thimbal. If care is taken in removal, they can be cleaned and reused. My mechanic friend told me that, without exception, he always just throws them away whenever he services the fuel injectors. I have kept them out and my engine has never run better. Good luck.
 

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Hmmmm... I will have to check that out myself. I have never heard of that before, but sounds like good advise.....
 

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Discussion Starter #4
Maybe ill look for a used set and send them to mps for cleaning and install come winter time. Not tearing bike apart for my short riding season here. Just wont ride as crazy as I usually do and keep it under 4k :(
 

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I am currently getting 110hp and 133ft/lbs torque with the PR 110" and speedstar cam. Although my map is also @ 100% fuel on the upper (5000 and above) rpm and 100% throttle with the stock injectors. My bikes an 06 with about 30,000 miles. I was concerned with this altough the hp and torque we very good. I suspected that the injectors need to be cleaned/flowed in the off season.

A while back, after the custom map, I was playing with NOS and drag racing and installed a Walbro hp 250 Lph fuel pump for more fuel supply for the increased NOS. It raised my fuel pressure about 43 psi to 48 psi. I would not really recommend the fuel pump install as although it works fine, it requires some ingenuity to install as the pump is slightly longer. I'm just mentioning this because although the bike still pulls strong I now have a slightly richer plug reading and don't seem to get the same mpg.
The bottom line is I think you should get your injectors cleaned and flowed ( especially if you got years or miles on your bike) before you get your final custom map. I plan on getting my injectors cleaned and flowed and my PC remapped this winter.
 

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I am currently getting 110hp and 133ft/lbs torque with the PR 110" and speedstar cam. Although my map is also @ 100% fuel on the upper (5000 and above) rpm and 100% throttle with the stock injectors. My bikes an 06 with about 30,000 miles. I was concerned with this altough the hp and torque we very good. I suspected that the injectors need to be cleaned/flowed in the off season.

A while back, after the custom map, I was playing with NOS and drag racing and installed a Walbro hp 250 Lph fuel pump for more fuel supply for the increased NOS. It raised my fuel pressure about 43 psi to 48 psi. I would not really recommend the fuel pump install as although it works fine, it requires some ingenuity to install as the pump is slightly longer. I'm just mentioning this because although the bike still pulls strong I now have a slightly richer plug reading and don't seem to get the same mpg.
The bottom line is I think you should get your injectors cleaned and flowed ( especially if you got years or miles on your bike) before you get your final custom map. I plan on getting my injectors cleaned and flowed and my PC remapped this winter.
As I said in original post bike only has 7k miles. Additional info is it is an '07 but only in service since May '09 with 12miles when I bought it new. The injectors can't be dirty. Too many filters before fuel even gets to the injector pre-screen. Its strapped to the Dyno now getting tuned and we ran into this.
 

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I am getting my best power/driveability with the speedstar injectors and an aftermarket fuel pressure regulator. 38# (for me) ended up being the magic number. The factory fpr did not give a consistent pressure.

I actually think that I can get a bit more power by tieing the fuel pressure to the manifold vacuum, ie wot=low manifold vacuum=higher fuel pressure and the inverse for low and mid rpm.

The rains have finally quit so that project is put off for a bit.

By the way, my stock injectors were maxed on the duty cycle also, I do have engine work, tho.
 

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Discussion Starter #11
Give it a try you might like it, mine has been connected in that manner
since about '03 :~)
How did you go about doing that? What was needed? I am not changing the injectors till winter time and just going to ride the bike like a normal person this season.
 

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On your stock fpr you will notice a tubing that is left open to the atmosphere; if you connect that to manifold vacuum, you will now have manifold variable fuel pressure. Pay attention to your sparkplug readings because you will now have less pressure and therefore leaner midrange readings.
 

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On your stock fpr you will notice a tubing that is left open to the atmosphere; if you connect that to manifold vacuum, you will now have manifold variable fuel pressure. Pay attention to your sparkplug readings because you will now have less pressure and therefore leaner midrange readings.
Would the Dyno tune be able to cure the midrange lean? Or will I always have it?
 

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This is why it is important to check your plug color; mid-rpm, partial throttle is "cruise"
You want that to be as lean as is safe to extend the mileage on these "100 miles-to-fill-up-creatures".

Hey, Google end-of-line pressure regulators to get a handle on the concept of how these regulators work; it will make your thoughts on this easier on you.
 

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Discussion Starter #15
That I shall do. Thank you.

repsol I sent you a PM.
 

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Discussion Starter #16
I am still looking for more input from anyone with understanding on this subject. The more chatter I can get going in this thread the better off I can be in pin pointing what the heck is going on.
 

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Churchkey, other than Repsol's reminder to re-tune the power commander, may I ask about any unintended side-effects of this solution, and also any other mods needed to accomodate the change? Or did you just run a hose to a manifold vacuum point, re-tune, and call it a day?

Give it a try you might like it, mine has been connected in that manner
since about '03 :~)


 
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