so i bought a 2002 F4I. the longer i own it and prep it for track days, the more horrible mods and just shotty work i discover. not joking so many things were disconected, arcing falling off, it only goes to prove how bullet proof hondas can be. so as i persistently cure these issues one issue is persistently building. it used to run clean all the way through my local canyon and back. then slowly as it got hot (mind u my engine has only seen 200 degrees once) i would come to a red light and it would idle rough, almost like it was dropping a cylinder. if i semi launched the bike as oppsed to slowly rolling into as if cops were behind me, it would go away. then it started doing it at 15% percent throttle or less. and everyday when shed fire up it would sounds ****. but if i rode on the street at all as opppsed to the freeway the problem would return faster and faster. then one day i got stuck behind a chp for 4 miles stuck at low rpm and 25% throttle. clear him and it was running on 3 for sure. it sounded like a ninja 250. it never cleared out all the wsay home. now when i start it the problem is there before the guages even register temp. ive replaced vacum lines and sealed them better, replaced in correct plugs, tested coils and injectors........ive had the engine completely out 3 times in the last month. my first track day of the year is monday, and short of a miracle im not gonna make it. oh and the only code that comes up is speed sensor. i have triple digit hours invested in this bike, over $4500 and its my only escape from everything. my father could die any day hes more heart broken by the fact that i can put 18 hr days into this biike day after day, and now its not even rideable. more importantly i cant go do laps. being the god son of the owner of willow springs raceway going to the track is my purpose waking up. im pretty much outta money. if anybody tooke the time to read this and has any suggestiions im humble enough to try any of them, even if i already have. i apologize for the length but i felt it was necesary to put the whole situation into perspective.

 

Hi Scott, the only other things that I can suggest are the fuel pump and / or fuel pressure regulator which have been known to give those sort of issues.
Hope you get it sorted and can bash out some laps

Cheers
Al

 

I'd start with the pressure regulator.
When its cold it needs extra gas, so a bad reg dumping gas might be masked.
At freeway speeds and hi rpm, it needs more gas, again masking the issue.

Otherwise, I'd guess something wiring wise judging by your description. Might be worthwhile to do a whole harness swap. Had to do that to an ex's R6 that she had up in MN for a few years.

 

To kick in the obvious open door:
For proper power 3 things are required:
- heat( spark, however you replaced the sparkplugs and coils)
- Air (Have you cleansed the throttle bodies and are the valves turning smoothly) I dont expect the airfilter because then in high rpm's you would loose power.
- Fuel, Do you hear de fuelpump prime? If it starts easy I would not suspect the fuelpump but rather the fuel filter or any other supply line...
Please also consider the post above where the fuelpressure is mentioned.

I hope this might help. And never give up. The problem is not diffucult, just hard to find...

 

Sounds EXACTLY like the typical honda regulator/rectifier failure. Replace the r/r with a mosfet unit from a 600RR or suzuki.