fueling issues?

So my bike has developed a surge of sorts. At part throttle any gear any speed, it will kind of "bog". If you continue to hold throttle at the same point, it will randomly run right and power will come back on. Then randomly itll go back to this
"boggy" state.

I pulled the carbs and cleaned all jets and passages. The jets were a little gunky but it ran ok before. Ran normal for about 15 miles and then back to this boggy state.

I thought it may be the fuel filter so i took it out. Same thing

Tested the fuel pump last night with jumper wire to bypass the relay. With the key on, the fuel pump pumped out over the 900cc/min. I got a little over 1000cc in a minute. I swapped fuel cut relays with my brothers bike and same thing.

I measured voltage at the red connector that the fuel pump plugs into. I believe this would be voltage from the relay. I got about 6.6v at idle. Didnt try to rev it up as I had both hands holding my leads on the volt meter.

Any ideas? I will be pulling plugs today to see what they look like. Bike is stock jetting im assuming. New K&N air filter, no snorkel, open header. Havent gotten around to fabbing up an exhaust yet. Im sure plugs will show if its running too lean.

 

6.6 volts is not correct, all circuits should be 12 volts, check connectors for corrosion which will cause resistance that will cause a voltage drop.

Check battery connections, if ignition system is getting 6.6 volts also will cause weak spark.

 

hmm when i swapped fuel cut relays i only got an increase to 7.7v at idle. I know my brothers relay is good. His bike runs fine. I will test the stator also along with pulling the plugs. Its odd because it ran fine for about three weeks. This problem is new.

So check plugs, check stator output.

 

Start with voltage readings at battery terminals, then check other systems, at 6.6 volts lights would be very dim.

 

I checked voltage with the bike off and it was 14ish volts. haven't checked with the bike running yet. Also running full led lights so my headlights are still pretty bright.

 

Then focus on wiring for fuel pump and ground connections.

 

connections for pump are all good, will report back after i check plugs and stator

 

Still need to get full 12vdc at pump terminal/connection.

 

hmm i guess i could jumper wire the relay out and see what i get at the red connector. I thought the relay was either on or off?

 

Contacts should not drop voltage, fact that you tried a second relay confirms contact OK, look for bad connection or bad ground.

 

Checked all connections and everything is good. Checked stator also good. Heres my udpate

ok update: Changed the fuel pump runs a bit more consistantly now. No more stuttering in the hi gears on the highway. Current specs:

40 pilot
130 main
one shim on needle
KN air filter
Open pipe
Pilot screws 1.5 turns out

Im having a slight bogging just off idle when i start moving. I have to ride the clutch a little bit to bring the revs up. Haven't stalled yet, but its noticeable.

Second problem is at highway speeds im still having to be 80%-WOT in order to maintain speed (probably around 80mph - no speedo). If there is increased load such as the hills on highway 4, trying to pass in 6th gear is very difficult. Im pinned WOT and I will just be able to slowly pass cars.

Not quite sure where to start this new diagnosis. I know its running a bit lean on the main jet as Im getting quite a bit of backfiring on decel. I had it jetted at 42/140/2shims and it ran like shit. I put the 40/130/1shim back in and it ran well enough to ride to work but with the symptoms mentioned above. I will be pulling plugs tonight.

One thing ive noticed is the exhaust note isn't "Crisp". A non baffled vfr750 v4 should have a very sharp nascar tone to it. It sounds kind of boggy and soft if that makes any sense.

Also just got rid of the pair system. Capped off the two vacuum ports on the front two cylinders and capped off the ports on the heads. I think thats it for things to cap off. I found this thread after the fact and saw all the evap crap. My bike didnt come with any of that. What should i check to make sure they capped off all the things for evap removal. I cant find any clear threads on that. Here is the thread i am referring to. primarily post 34
http://www.vfrdiscussion.com/forum/index.php/topic/74133-jetting-after-pair-valve-removal/page-4

Any ideas?

 

Running too open an exhaust will cause problems at various rpms that can't always be dialed out, besides the excessive noise. Trying for the supposed sound of horsepower may actually be reducing hp !

Off -idle stumble needs custom tuning of pilot screws, backing out 1/2 turn up to possibly 3 1/2 turns until problem disappears. Maybe larger pilot jet would help. No doubt made worse by open exhaust.