New here so first off I would like to say hi all. I have read alot of the threads here and have picked up a great deal of knowledge. I know this kind of issue has been touched on quite a bit but from I have read and tested I have been unable to solve my problem, so here it is. I bought my 2000 f4 about 5 months ago and have been loving every minute of it up untill it started doing this. I am having the common problem of when my bike gets up to operating temp and the fan comes on it wants to stall but I can keep it running by increasing the idle. I have ran a number of tests from this site and here's what I have come up with. When my bike and everything on it is cool it runs great and charges at around 14 volts, which is fine and dandy. Once it gets up to temperature and has cycled the cooling fan a few times my charge drops to around 12.6 volts. When i rev it up to about 2500 rpm it charges at about 13.5 volts. I have changed out the RR with a new one and same thing. I have also checked the battery and it holds stong at 12.5 volts. The stator checks out fine aswell. I have aslo checked all my grounds ect. And have been unable to solve the problem. I will also say that I checked everything at cold and hot with no difference other then the voltage at the battery. Any help or advise on what else would be very helpful and sorry for the long post but i wanted to make sure it was clear as to whats happening with it.

 

Mines doing the same thing.... baffling!

 

I'm pretty sure you guys are having the same problem I've had for 2 years and I finally got mine fixed - been running for 2 weeks with not a single stutter and it's been in the 90's and 100's these last week. Here is what you need to test to see if you have the same problem. After riding your bike home from work or something and your bike is stuttering, pull your seat and rear fairing off and check the voltage on the black/white wire on this (see pic below) relay (there are 2 black/white wires - either will work). Report your voltages back here. I'm getting ~10v and it drops to around 7v when the fuel pump kicks on. Let me know what your voltages are so I know we're all having the same issue.



If yours is doing close to the same thing I have an EASY $5 fix for you.

 

when the fuel pump kicks in or when the fan kicks on? What is that relay for anyway? it's listed as just a "RELAY, POWER (5P)". Mfg. Part Number: 39793-SV4-003

I guess that 5P means 5 pole..

 

dug up an old post that (if correct) describes what the power relay does... cause mine still does it when the fan kicks on.. slight but its there.. doesnt stall.. but I'm pretty sure it's not a voltage issue either...

Posted from https://cbrforum.com/forum/cbr-600f4...stions-110917/

A new power relay from Ron Ayers is only $25 but from you are saying the relay isnt the problem.. its the voltage that it's getting (or lack thereof)

 

You are correct, it's not the relay or any part for that matter. It's either a connector up by ignition or a bad wire in the harness. But what I've found is that circuit is able to get enough power. Not because it's shorting out, it just simply isn't getting enough power. I ran a wire from the battery to that circuit and instantly my bike was running like it's supposed to. I've been running it like this for a few weeks and I haven't had a single problem. And my voltage doesn't drop below like 12v on that circuit. I'm going on vacation next week, but I'm going to build a new circuit that has a relay on it that turns on that circuit instead of the wiring running from the battery all the way up to the handle bars and back to the back of the bike - that's a lot of wire for something to go wrong. So I'm going to simplify it and see what happens.

 

I'm anxious to hear your findings... Im inclined to agree with you that the charging system itself is not necessarily to blame here.. When my fan is on Im seeing high 12vs at the battery (DVOM).. and it has that stutter.. well when I start it up cold and turn the choke off. the idle can drop to even 1000 rpm, where the throttle response is crisp and I measured the same high 12s with the same DVOM.. so therefore although the charging voltage might have something to do with it, it doesnt seem to be dependent solely on charging voltage... I am going to pull my tank and check my chassis grounds.. I believe that there is one common ground on the crossbar that runs under the back of the tank.. I think there is another ground point at the starter... are there any others? I'd like to be sure that they are getting a good ground.. maybe run another wire from the negative battery terminal to that large comomn just to be certain to take that out of the equation... cheap and easy to do and test..

 

Turbulenz - have you checked your voltage on the circuit I'm talking about??? It's not a grounding issue either, or I would be having the same problem even with the jumper wire connected. Take your DVOM and check the voltage on that relay I have in the pic above - if it's dropping below 10v, you have the same problem as I do.

 

No I have not. I will try to do so this week and let you know. I just don't understand that this being such an incredibly common to the f4 and nearly everything that I have read leaves it unsolves or as a "deal with" issue. A low number of people have found success with new regulators but for the most part this seems to be a dark art....

<shrug>

 

I'm honestly thinking it's too small of guage wire for some of the circuits then you add older age to them and they just don't flow enough current like they used to. It could be a connector issue too, but I haven't been able to find anything that seem to be the culprit. Once I get back from vacation I'm going to install a relay to replace my jumper harness and see if it continues to work as well as it has the last few weeks. Please let me know what you find by testing the voltage at that relay.