4500 rpm flat spot

Newbie here with a recently purchased 04. with the exception of a K&N and gutted mufflers the bike is stock.
I've utilized the search but found nothing similar to what I'm experiencing. My bike has a very noticeable flat spot at 4500 rpms. Seems worse when its cool out. I find myself down shifting while cruising to avoid it. Any one else experience this ?
I just turned 17k and according to my local dealer the valves were checked back in 08 but no mileage recorded.
Some friends think its the gutted mufflers causing this, but it seems to be a popular mod so I'm thinking otherwise.
Thanks guys.

 

I guess I'm alone here. Well the flat spot is now between 3 - 4500 rpm, and its driving me crazy. I'll figure it out eventually and ill post up. Maybe it will help someone.

 

There have been 2 times my 99 has had a mid range flat spot, once when I tried the snorkel mod before a 1200 mile ride. Must admit to likening the sound but hated the flat spot so put the snorkel back in. The second time was when a pair valve gummed open but the fuel economy also went bad pair valve mod fixed that one.

 

What exactly is the pair valve mod? I've read threads about it, but nothing really explains what it is, and how to do it.

 

There are a few how tos around. The PAIR removal helpednme out with throttle control but mostly at very low speeds/ rpms.

The system takes a small Amount of intake air to dilute the exhaust a little bit. Oxygen sensors in the exhaust are used to tell the system how much oxygen to bypass combustion and just get mixed in with the exhaust. I did the mod out of curiosity and I like the results.

Essentially all you do is block off a vacuum line in the air box and then install block off plates where the valves themselves are (intake)

 

If you have no cat and gutted cans but dint add a computer do run a fuel map to adjust for that, you can all sorts of issues. Flat spot, bad gas mileage, etc. if you go the route to a computer like a Power Comander, go ahead and do the pair removed and bypass the o2 sensors. You can even look to a Power Comander V with replaces the o2 sensor and used the info to auto tune the map.

 

Thanks guys, I have the cat, but the cans are gutted. I found a link which described the pair mod as just unplugging an elec connection on the right side just aft of the airbox. I did that along with disabling the vaccum flapper valve. ( according to the link, this is supposed to cure the "5000 rpm flat spot"...maybe this is my beacon of hope .
Going for a ride today to see if there is any improvement. If not, its Power Commander time for sure.

 

PROBLEM SOLVED! That did the trick. No more touchy throttle, no more surging/flat spot.
It's running smoother than it ever has.

 

Glad it worked out. Enjoy!

 

if you want to smooth it out further, o2 sensor eliminators are next.
then a power commander and tune.
probably the ultimate solution would be a pc5 with auto tune.

 

That is next on the list. I can't believe what a difference those small mods made. I was considering +2 on the rear sprocket, but the low rpm responsiveness is so much better now that I may not fl it.
Who has a good price on the Power Commander?

 

Mmmmm surging = lean.

 

DynoJet Power Commander Honda VFR 800 PC V USB Fuel Tuner 2009-2010 - Tobefast

Dynojet Power Commander V Honda VFR 800 VTec - Indysuperbikes

Dynojet Research Power Commander V for Honda VFR 800 VTec 2009 - 2WheelPros.com

2009 Honda VFR 800 VTec DynoJet Power Commander V (PCV / PC5) USB

Dynojet California A.R.B. Approved Power Commander III USB-EX 101411EX

Dynojet Power Commander V PCV PC5 HONDA VFR800 09 on eBay!

DynoJet Power Commander V USB for Honda Interceptor VFR 800 2009

 

on a side note, dont worry about them being listed as only 2009 and up. this is bullshit. theyve already fitted them on 5th gens and everything in between...

 

Thanks. I'll be getting one soon.

 

no prob buddy