I run 93 octane constantly and it hasn't helped much. And with spark plugs I am using NGK iridium and they are working great so far.

 

Running higher octane will do nothing for you, I promise, and have spent time on a dyno getting better power out of 87 straight from the pump then the 100+ sunoco stuff (and thats after advancing the ignition too), our bikes are tune for 87 and honestly everything will see more power gains with lower octane because the engine has to use less energy to ignite the fuel. The reason octane is increased is to avoid detonation not to increase power. As far as the electrical problems you guys are having have you guys checked your R/Rs? They are a known problem with F4s and early F4is and Honda has redesigned them so if you try to order the old one from a parts dealer you get the new one. I had this issue for awhile and it made me scratch my head too but, after going through and testing everything else with a multimeter, it was the R/R. Hope it helps.

Fun fact 87 race fuel costs more then its 100 counterpart.

 

I tried higher octane and it made it worst. I installed new Pilot and Main Jets and it helped tremendously. The only thing I didn't do, was replace the shims on the needle, that came with my Jet Kit. I'm sure once I do that, problem will be solved. But I don't know how to remove the needle from the diaphragm. Ugh.... Always something.

 

Hello I am new to the forum and ready for some input. I have a 2000 cbr f4 I got it with 21000 miles on it and bleed the brakes and fresh oil change and oil filter. Now my problem is ONE bike

 

i had the same identical issue plus the bike would get hot, except it wasn't from overheating type of hot, I know sounds goofy... All I did was cleaned the carbs, installed new jet kit (replaced shims on the needles also) and replaced spark plugs.... problem solved. Dunno if it will work for you but that's how I cured the issue.