Bought a 02' F4i 3 months ago with 3600 miles. Currently has 6700 miles. Recently the following issue started:

Turn on bike and the engine bogs down as if either one cylinder not working or engine is on choke. This is even after the bike heats up to 175 F+. Recently replaced spark plugs to try to fix the issue. Noticed that 2 of the old sparks in the middle on the engine block were black, but the ones outside weren't. Ran good for a day and now I'm having the same issue. Engine Bogs down. I think my bike is running super rich and is causing residue on the sparks. Don't know y though.. sensor is bad or is it the injectors? My friends and I have no clue. Any expert mechanics out there willing to take a shot at this one?

 

sounds kinda similar to what happened to me....couple of questions
does it surge at constant speeds?

is there rust in the gas tank?

has someone removed the airbox before?

The palcement of the velocity sttacks are very important to how the bike runs the stacks are staggered and the taller stacks go on the outer sides not in the center.

the rust thing... you are not going to like this "if" this is the problem. The tank will need to be replaced or coated inside. tthe fuel pump and filter may need to be replaced as well as injectors. they may be sticking open and washing out your cylinders. This is worst case and may not be the problem. One way to tell if they are leaking is to smell your oil to see if it smells like gas or if the level has gone "up" for no reason. Very poor gas mileage is another clue(less than 100 miles per tank)

This is just suggestions and may not be the problem... it could also be electrical does the bike sit in the rain... if all else fails... Take it to the dealer or a good honda mechanic.
hope this helped

 

sounds kinda similar to what happened to me....couple of questions
does it surge at constant speeds?
Yes it does surge at constant speeds.

is there rust in the gas tank?
Couldn't check the inside of the tank for rust. Nothing that I saw.

has someone removed the airbox before?
I removed the airbox a week ago to replace the sparkplugs. All the sensors are plugged in.

When I was replacing my spark plugs. I ran a multimeter to test to voltage of my battery just to make sure it was good but it kept reading at 19Vs. I don't tihnk that's normal. And I just smelled my oil and it definately smells like gas =/. What does that mean? Gaskets? Clogged Injectors? Leaking Injectors?

 

Can't he put the ECU into diagnostic mode on this one?

 

what was the last thing you did before the bike started to act up?

did you just pump gas, etc.?

 

I am not 100% sure about these answers but this is what worked for me.

constant speed surge
Your v-stacks are backwards... You would think from looking at it that the tall ones go in the center, but they don't. Mine were in backwards and when I put them in the right way... man what a difference it made...There is a "small" tab on the base of the stack on one set and there is a small tab on the air box where the stacks sit. They are not meant to line up but if you line them up the tabs will crush. This little detail made a big difference on my bike.

as for the black plugs
you need to have a leakage test done on your motor not a compression test. There is a difference. a compression test will tell you a difference in pressures between cylinders and a leakage test will determine "where" the air is going i.e. valves(which one..exh. int.) or rings.

I have the same symptoms as you do so I knw why you say "even when the bike warms up" because most of the time it runs like crap until it warms up and even then you may have a little trouble starting and those who follow you tell you you are running rich.

Ever try to start your bike and it seems like the battery dies cause the motor wont turn and you come back a while later and it starts?

oh well.
do the leakdown test and if it is the rings you and I are in the same boat trying to plug the holes with our fingers when what we really need is a new boat... or should I say motor.

 

Prob. started a month ago.. it would do it from time to time. But would eventually go away. My friend just rode my bike and told me that's its f**ked. Most likely a leaking injector. Runs so rich that eventually the spark plugs go bad. The bike smell gas and the oil smells like gas. I would take it to honda.. but the cost of their service, it would prob. be cheaper to just replace the entire fuel system myself. =/. Any of you guys know how to properly test each injector? I already put 10 miles on it with a full tank and Techron Fuel Injector Cleaner with no difference.

 

:Bump:

 

Hey dpg let me tell you what I am in the process of doing. I am about to change all these items probably tomorrow.

FUEL TANK (USED NO RUST GOOD COND)
FUEL PUMP(IF SOMETHING SCREWED THE INJECTORS THERE IS A GOOD CHANCE THE PUMP IS BAD OR WILL BE NEXT)
INJECTORS(i HAVE 1 CYL THAT FOULS PLUGS BUT AM CHANGING ALL 4)
Even though I change all these items I truly belive that the plugs are black due to oil leakage through rings. BUT before I change the motor I gotta fix what caused it to go bad.... Yes I did say change the motor. because after this I already changed every thing else. DPG there are places that recondition injectors. I have heard of places that flow balance them too but all I am tryin to do is get my bike to run smoothly.

 

i had a problem with an f4i i just bought that is similar in some respects. i never rode it out of first gear before tearing it apart to make it into a track bike. but i did notice it ran like crap when i first started it. to make a long story short, the map sensor vacuum hose was cut, and the guage cluster wouldn't register an FI error code (i had an extra one lying around which did and helped me solve the problem).

i got some vacuum hose from advance auto and it ran great after that.