Hey, everyone! I've been creeping on this site for the last few months and have learned and fixed a lot because of it. but I cant seem to find a fix for my problem.

I bought a 99 cbr f4 about a month or so ago with around 34k on it. I live in nyc and have been sticking mainly to the streets. A few weeks ago I took it on the highway for the first time. as I got off at my exit going around 50 I pull in the clutch as there's a red light coming up and the bike died. it started back up no problem. I figured it was something I did... a few days later (second time on highway) same trip same thing happened. get off the exit pull the clutch bike stalls. this time it didnt really want to start back up. It dropped off sharply to 500rpm for a few seconds before falling to zero and dieing if I'm not mistaken.

I put in a new R/R because it was stalling when I had my turn signals on and the fan would kick on at red lights... the R/R fixed that problem and I was hopping it would fix this as well. I also took it to my local shop explained my problem waited around a few hours and I'm 99% sure all he did was raise my idle... to high.

So last night the highway was pretty empty and I was riding with a friend so we went on the highway (after we've already been riding for an hour or so) I was going about 70-80 and maintaining around 7k rpms for a good 10 minutes, then came up to a slight incline, and felt the bike slowdown. I gave it a bit more gas and felt it barely maintain speed. So I up shifted (IDK why lol). still feeling wrong and slugish, so I turned the throttle all the way and looked down and saw it was at 4000 rpms. I was luckly pretty close to an exit and was able to putter off the highway at about 4000rpms with the throttle fully open... while on the exit ramp it dies, oil light turns on (which is normal right? mine is always on if the engine isn't turning.) I tried a few times to start it back up while rolling, didn't start.

So I'm pulled over tried starting it a few times it wouldn't start. I oppened the gas tank to hear if I heard air rush into it. nothing. Sat for a few minutes tried two more times, it started but sounded really weird. really uneven sounding, it sounded to me like one cylinder wasn't firing (but I don't know what that sounds like lol). let it sit a few more minutes and it started fine, and I rode it home on the streets with no problems.
Sorry for all the details but I feel they must be important! lol.

Some other info i feel may be relevant. My hot idle is around 1500. I changed the oil after buying it and used castrol full synthetic 10w40. from what I understand I shouldn't really be using this but I figured I could get away with a few hundred miles before changing again (could this be the issue?). I just flushed and changed my coolant today (read somwhere somone with a similar problem did this and it fixed it), there was some crud in the bottom of the reservoir even after flushing (the coolant looked very clean though)... I decided it would be too much work to get it out... filled it up and trying to erase the crud from my memory... I changed the spark plugs a few weeks back with iridium ngk's... the regular ngk's I took out looked beautiful though . bought the battery the day after I bought the bike, put it on a tender almost every night. All the connections are tight and secure (checked today). The vacuum lines on the air box look like they could use replacing (kind of dried and cracked looking, could that be it?).

also my oil pan plug screw (that's what I'm calling it) seems to be dripping the slightest bit of oil, its always all wet with the stuff, but there are no droplets in my garage.

I think thats about it... If you made it through all that thank you so much! any help would be greatly appreciated!

 

Just got back a little while ago, tried the highway again, same story cruising around 70 at around 7k rpm, and the rpms just started dropping for no reason around 4k I pulled in clutch and it stalled. tried turning it back on while rolling, no go. I had to walk it up part of the exit ramp tonight :/. I tried starting it and nothing. sat for 5 min tried again, started but sounded weird again, blipped the throttle a few times and it barely idled at 1000 but sounded okay. After a few blocks of riding my idle speed was suddenly 2000 which is 500 over what its been all month... So i put it back at 1500 and rode home with no other issues...
thanks again!

 

Just curious... you're sure you put the right amount of oil in? And does the bike call for 10w40?

10w40, 40 meaning it will be thicker when warmed up.You said the problem occured after running it awhile with no issues.

I have heard(never experienced) that too much oil or oil that is too thick can cause these motors to run like complete ****, if at all.

I know its an obvious one but I figured Id ask anyways.

 

Hey Chris thanks for the reply,
Yup manual calls for 10w40 "Honda gn4 4 stroke oil or equivalent motor oil" to be exact... I thought any 10w40 would work but the guy at the shop said I should be using motorcycle specific oil... IDK

There's a possibility that there is too much oil but I don't think so... I feel like I'm always checking the oil all wrong, but I think I just think too much lol. When I check it I've been turning it on, letting it run for a minute or two. Then I shut the bike off wait a few seconds, pull toward me as straight as I can get it and look at the window, and make sure the level is between the two lines...
I guess an oil change is in my near future lol

I've put almost 600 miles on this thing since I bought it and have had no problems with it except for on the highway. I just don't understand why it runs perfectly on roads at all speeds and rpms, but on highways it just doesn't.

When I first bought it I took it to the shop and was told I needed new steering bearings, top and bottom (I think thats what they were called), a new fork seal and my calipers rebuilt. So I let the shop do that stuff as it seemed pretty hard. I also just ceramic coated the exhaust and have a leak in my slip on the last few days... I know, I know... I'm working on it
I don't know if any of these things change anything (pretty sure they don't)... just figured since I was typing :P

Chris Thanks again for your response!

 

yo zan try the spark plugs check them... bc if u have bad spark plugs u tend to no get any power out of a motor, before i got my civic, the lady said it wont go up a hill, so im like sure lol, but once it got home i checked and it needed spark plugs and wires, and usually they tend to bog down and u cant go over that many rpms, for me i couldnt go over 2500

 

Cuetip thanks for the reply. I'm going to check the plugs today if I get around to it but I'm 99% sure they'll be fine. I just replaced them a few weeks ago and the old ones looked brand new.
But I ride up some steep hills all the time with no issue (on the streets) And the engine runs fine at all RPMs its just something about steady even riding that kills it...

I'm trying to take off and clean the carbs right now... followed the manual to a T... I can get the carb assembly to come off the cylinder heads for some reason

 

get that carb cleaned, lol if not grab an f4i motor since it will bolt right up to that frame

 

I'm not as familiar with the F4 as I am the F3, however there are many similarities. The F3 was notorious for having the Fuel Pump fail (it's the contacts that go bad) and leaving you stranded on the side of the road.

The symptoms you're describing certainly seem fuel related. It seems that you're bike is starving for fuel at higher speeds. Do you have the Honda Shop Manual for your F4 ? I was looking at it this morning, reviewing the Fuel Pump control and the Wiring Diagram. Honda added something to the F4 that wasn't on the F3 and that's a Fuel Pump Transfer Relay.

During slow speeds, less than 18 mph, the fuel pump gets a pulsed signal to it for operation. It's controlled by the same signal that handles the #1 Ignition Coil/Spark Plug. When your bike reaches 18 mph the Speedometer provides a Ground to the Pink/Yellow wire coming from 2 relays. One is the Solenoid Valve Relay (controls air flow to the carburetors) and the other is the Fuel Pump Transfer Relay. The Fuel Pump Transfer Relay provides battery power to the Fuel Pump so it's running continuously.

A couple questions for you.

1. Does your Speedometer work ?
2. Do you know if the Solenoid Valve Relay is working ?

The Solenoid Valve Relay is turned on as soon as your turn on your Ignition Switch and the Engine Stop Switch is in the run position. It makes an audible click when it does. You can flip the Engine Stop Switch from Run to Stop with the Ignition Switch turned on and you should be able to hear that relay cycling. It's located near the rear of the fuel tank towards the right side of the bike as you sit on it.

Let us know what you find out and we'll try to go from here.

 

Yes I do have the service manual IDo (couldn't help myself :P)
Yea I'm fairly certain my issue is fuel related, unfortunately I have to run to jersey right now so I can't check these things out today
My speedometer works fine... but I dont think I've seen it go as low as 18mph :P.
I'm looking at the page right now with the solenoid relay... Should I run the beaker test they mention?
I did notice the other day (for the first time) that when I would turn the key to on, with the kill switch also on that the bike made a clicking sound from under the right side of the rear cowl, I'm fairly sure that what that was making that sound, right?
I think I remember reading somewhere the other day that just because its making the sound it should be making doesn't mean that its not broken. So I would say no I don't know if its working but I assume so lol.

Now the bike is a 99 and I'm the third owner. The guy I bought it from bought it about 8 years ago and only put about 5k on it. It dosnt seem to me that he did all that he could and should to make sure it would run well for a long time... I was kind of hopping all I had to do was clean the carbs... but now I hope that's not the issue as I still can't get them off!
Can I call it quits on the carb?
or any ideas why I can't get it off? I disconnected all the hoses and tubes, loosened the 4 insulator screws as far as I was comfortable loosening them, and took off the choke cable. (didn't take off the throttle stop screw yet, figured I'd do that once the carbs were loose) And after all that the darn thing only wiggles maybe 5mm when I try moving it with all my strength.
I was also wondering if a dirty fuel filter can cause these problems? should I replace it? and also my fuel filter's rubber mounting thing is ripped completely off, I'm thinking I'm going to replace the both of them.

Let me know what you think, Thanks!

 

It woudn't hurt to do that. You'd be able to see the fuel pump in operation. The fuel pump has a single screw that holds the black cap on end. Taking that loose will allow you to watch the pump working. The reason for a working speedometer is that the Pink/Yellow wire gets a signal from it to turn the valve you're hearing off. It's true that hearing the sound doesn't prove it's working correctly, but it's a start.

Your bike is 13 or so years old. The rubber boots holding the carburetors to the Intake manifolds are hard and stiff. It can take a bit of elbow grease to get them off. You should be loosening the clamps that are closest to the cylinder heads as opposed to the ones closest to the carburetor bodies. On the F3, there was a place on the left side of the top part of the frame that I could put a hefty screw driver against as well as between the carburetor bowl/body and encourage them to come loose from the head. Naturally you've got to use some caution when applying this method of getting them loose as you could conceivably crack or break the carburetor body (that's a bad thing) and this is to be avoided at all cost. I too don't take the throttle cables off until I've got the bodies loose from the heads.

I wouldn't be too terribly concerned about a dirty filter, other than to say replace it at your earliest convenience.