Hey guys, I'm new to the site.. I've been lurking for a while, but my latest problem led me to register.My bike is a Red/Black 99 F4. Its got around 17k miles on it with a few mods.

The problem im currently having is with throttle response. It seems to be worse when its colder rather then hot, which makes me think I may be a bit lean? I've been doing a lot of wheelies lately, and when I blip the throttle to clutch it, it hesitates and struggles to get up in rpm's.

I have only owned this bike for about 3k miles now, so I dont know when the carbs were cleaned last. I replaced the plugswhen I got it, so that shouldnt be it, TheK&N isof the same age as well.I was going to sync the carbs today thinking it might help, but they were all very close to eachother and decided to leave it alone. If the clutch is engaged and im riding around I dont really notice any hesitation, unless im in 1st gear and give it alot of gas. Once it gets up in rpms, it seems fine though.

I've done several pulls next to my friend with an 02 F4i with like 4k miles on it and a PCIII and Two Bros pipe and were DEAD EVEN after like 7-8k rpms on up. He seems to have a tiny bit stronger pull in the mid range (4-7k) which happened since he added the PC.

I thought about just cleaning the carbs, as it seems like maybe the pilot jets(I think thats the jet that controls partial throttle) may be gummed up. Should I add a jet kit while im in there? Two brothers doesnt recomend one according to their site, but I didn't know what kind of experience you guys have with them. Id like the throttle response more then a gain in hp at this point.

If anyone has any other suggestions, Id really appreciate it. Thanks alot!




Heres a pic of my bike. Thanks again!

 

I would start off by getting the factory Honda Service Manual because of its trouble shooting. Make sure everything is in its proper placement such as the hoses. When you took off the spark plugs what color were they dark = rich and light gray = lean. You'll need a pilot screw driver to reach and adjust the pilot screw to get the proper setting. California type is 2 3/8 turn after it is seated and non -Cal is 3 1/8 of a turn. Once it is adjusted then you need to sync your carbs. Alot of details and you need a synchro equipment. Get the factory manual especially if you do the work yourself.
As far as jetting your bike, I did mine when I got the bike in 99 with Dynojet. Cost about $125 and took my time like getting paid by the hour. If your going to clean out the carbs mindswellchange the jets since your there. Recharge your K&N and make sure the hoses are in its place. Follow the instructions and you shouldn't have any problems.

Good luck bro

 

Thanks for the advice. I have the service manual too. All of the hoses are good, and the plugs looked good when I took them out too. When I changed the plugs, I took out the nasty bug encrusted stock filter, and put the k&n on, which is maybe why it feels a little lean now.

I checked out the troubleshooting section before, but nothing really applies to me. It runs great at WOT, and even most of the other time.This only really happens when I have a big change in throttle input, and the engine is either in a low enough gear to increase in rpms quickly, or if I have the clutch in to pop it up. If im cruising along in 5th for example, and twist the throttle, it gets up and goes, but I dont notice any hesitation because the rpm's arent changing fast enough for the problem to occur.

The only other time this happens is when the bike is cold. Like within the first few minutes of starting it, it runs horribly. It starts right up and idles good, It just doesnt like any input from the throttle.

I put the stock exhaust back on last night and it felt alot better, though ALOT quiter haha. I almost fliped the bike once because the response was so much better. When I got home, I put the Two Bros pipe back on and I went out again. The throttle response seemed better then its been, and it was cooler out last night which is when I've been having problems. It still wasnt quite up to par with the stock pipe though. ThenI did a few pulls from 2k on up, and felt no flat spots in the power band. It actually felt pretty linear, except for the little surge at 9k.

I think im going to try cleaning the carbs out this week if I get a chance. Thanks again.

 

Based on the fact you have a new pipe you most likely need a jet kit and to have it tuned by a professional.