power cuts out over 6k. please help!

I ride a 1997 vfr750 and I noticed when im getting on it there is a major lack of power and it hesitates/ surges.. my friend said it is popping out the tail pipe also.
This happens when im accelerating above 6k rpm. it doesn't matter what throttle position im at 1/4 3/4 wot, no matter. but once it hits 6k the power goes flat.
im thinking its not my carbs and maybe an ignition problem. due to it not being throttle position related. any help would be great!
also the bike is having charging issues lately. it has battery voltage at idle to 3k then it only goes up 1 volt from 3k on.. that cant be right and im not sure if its related.... brand new batteries fyi.... I am very mechanically inclined and have a lot of tools so don't be afraid to get technical.

 

Can you tell us more about the charging issues? You say it "has voltage" from idle and remains the same as you increase to 3K. What kind of voltage?

Charge your battery on a trickle charger. Bring it to a shop and get it load tested if you can. Yes its new, but its possible it was a shit battery.
It should be 12.8V to 13.2V when fully charged.

Start bike and check it at idle (once warmed up). Should be low to mid 13s.

Increase your RPMs and check at various intervals. At 5K, you should be around 14.5V, give or take.

Does the voltage remain steady, or is it jumping around, i.e. from 14.5, to 13.2, to 14.4 to 12.9... etc. It should be a constant, and not fluctuate.

What happens when you get to 6K RPMs? Does the engine stutter/hesitate of give any signs of losing power as mentioned above?

 

First off, battery issue.. I tested with the new battery and it is at 12.5 key off and low 13's at idle.. it reads mid 14,s from 2500rpm and up. which is a big difference. my old battery was totally sulfated and only holding a surface charge. there is no cutting out or hesitation at 6k or even 8k, didn't go any higher i don't care to rev in neutral.
second issue: power cutout/misfire at 6k and above.....Yes my bike ran like a dream until a couple weeks ago it felt like it turned off for a split second on hard accell up a hill. then i noticed it again on sunday and a fellow rider informed me of my exhaust note. now i did notice when revving testing the batterie today that i was getting some popping on decel where it used to be a clean purrrr. I just don't see how it could be the carbs if it runs great thru all throttle positions and gears at low rpm but when it gets over 6 it fall flat and starts popping out the tail. could be carbs but i thought it might be my spark dropping out or double firing due to pickup confusion or faulty cdi...

 

what would you suggest? pull the plugs and inspect, then carbs and do a visual inspection?
im looking at some downtime.. need a waterpump also. uhg!

 

i took out all the emissions crap last year. even removed the oxygen breathers in the exhaust (and plugged the holes)
It ran awesome sense then. well until 2 weeks ago. I need to pull the tank and run it while checking the slides. after that pull the plugs and carbs..
might be time to just do my 49 state cam carb conversion.. maybe..
I just hope im not looking at a new cdi.. do you know how dependable the pickup is on these?

 

Your chronologicals not making sense

Is this an old problem that went away after putting in a new (but weak if only 12.5) battery and has now re-appeared a couple of weeks ago? Or is the battery fresh today and the problem is still here right now?

Could be a weak battery that's laying down at high revs. If battery is new then is the charging system working

Could be a defective coil that insulation is breaking down at high revs--try running it at night and looking for flashes of light coming off the coils or plug wires.

Could be debris in fuel line (is there a filter?) that limits fuel flow at high revs so its running lean making less power and popping in exhaust. Or weak fuel pump not able to keep up with 6k rpm demand.

If the problem went away after putting in a new battery (several weeks ago?) and now it is back, then it seems like you still have an electrical issue more so than fuel.

Is it stock air filter and exhaust? Jet kitted? Does it do this on the stand or under load? etc. Lots of variables can contribute.

 

the batterie has nothing to do with the drivability issue.charging system is good now....fuel filter is clean. might be pump but i doubt it. where can i download a manuel so i can do some testing... good point on running it at night looking for sparks. im pulling it apart this weeking. ill let you know what i find.

 

Throw a new set of plugs in it. I've seen many times at higher rpms the same as what's happening with your bike turns out to be plugs/wires. As long as the RR is working properly and you have the voltage needed for higher rpms. It doesn't take much to trace a plug. For the price and time it takes plugs are the easiest way to go. I've seen newer plugs get traces. Possible bad gas has glazed/traced one or more plugs.

 

plugs! ah the simple things... good call. they are always the first to get inspected when there is trouble. that would be awesome if crappy gas was the cause. bad gas is a real problem these days, they charge top dollar for crap! you know i did fill up on that shell 91 oxygenated crap right before this happened.. hmmm

 

the higher the octain the more resistance to pre ignition and detonation. with these high reving carburated engines the possibility of pre ignition is a reality. especially with the 10% ethinal fuels in california. I say pay a little more for 91 and dont risk it!

 

There are a LOT of additional carb/intake ports on the bikes with the Cali emissions equipment - are you sure you plugged everything when you de-PAIRed it??

How did you plug the exhaust air injection ports?

 

Try running up to the 6k lean speed and hold it, then pull the choke lever and see if the condition clears/power is restored. If so then i'm thinking you have clogged fuel jets, sticking vacuum slides, or torn diaphragms.

 

what altitude?