Anyone solve their Hot F4 Stall issue yet?
 

The "fan turns on and my F4 starts stalling" issue seems to be a pretty prevalent one at the moment. Has anyone found a solution. Since my bike has the same problem, I figured I'd try to condense a bit of the info. So far, the operating theories are

• Bad CDI
• Bad Battery/stator
• Bad R/R
• Bad Fan

All of the above seem to suggest that it is an electrical problem that kicks in when the fan turns on because of the extra draw.

There is also the "your carbs are messed up" theory which most posters seem to abandon after spending a bunch of money or doing a bunch of work.

Am I missing any other explanations that have come up?
Has anyone had any luck yet?

I think what the F4 needs is the F4i stator/ RR as it kicks out 90 watts more than the F4. I think part of that extra wattage was for the fuel injection, but the rest was because the F4 was under powered.

If you do consider swapping the R/R then get one off a current CBR 1000RR or FJR - they're a different type of system... they are not as wasteful and tolerate more abuse.

Here are a few links:
http://www.vfrdiscussion.com/forum/i...howtopic=32021

http://www.triumphrat.net/maintenanc...r-upgrade.html

"Best widely available R/R on the market today is the Shindengen FH012AA used on the late (06+) Yamaha FJR, 07+ Yamaha R1, 08+ Honda CBR100RR among others "

I haven't done the swap yet - but I think I will.

Now would certainly be an excellent time - search on EBay for Shindengen & you will find a vendor who is selling ~50 of these at an incredible price!
(absolutely no affiliation with seller!)

Incidentally your quote referencing the 08+ CBR1000 has been updated - that R/R is actually an 014 model - uses different connectors.
I'm sure just as effective, just no known connectors available in the after-market (unlike the 012)

Did you happen to keep the link? I didn't find the 012

I would say for certain that it's purely electrical. Now, some bikes may have carb issues in addition which compounds the problem but the root cause is still the electrical power supply. I would agree that the charging system is undersized for the full load of the system but the battery is undersized as well. The electrical load is designed to all to be fed by the battery which in turn is re-charged by the stator-R/R combo. The battery has really 2 purposes. A) supply power for starting of the bike B) act as a surge suppressor for the load demand of the electrical system. In reality you could run the bike strictly from the stator-R/R combo but when different loads turn on and off, there would be a wild fluctuation in R/R output voltage and current. This over time would no doubt lead to the stator-R/R failing fairly quick. Vice versa you could run the bike strictly off of a fully charged battery, but obviously only for a certain period of time, as it wouldn't be recieving a charge from anything.

Now what's happening when the cooling fan comes on is an increase in electrical load. (Being fused at 10 amps using a 150% over load factor, would lead me to believe that the fan motor's energy consumption is roughly 6.7A or 80-90 watts. With the engine at a slow rpm, the stator-R/R can't work at full capicity (343 watts @>5000 rpm). The extra load in turn causes the battery voltage to drop resulting in what is really a brown out. Everything on the entire bike will be affected by this including the ICM and more importantly the ignition coils. If they aren't being supplied with the designed amount of voltage/current, there peak voltage output will not be as high as it should.

So all of that summed means that the poor run condition in hot conditions is mainly caused by poor ignition spark and/or erroneous ICM behaviour.

To correct this, I would install a stator-R/R combo with a greater output capacity and a larger capacity battery.

To test and troubleshoot this idea, in theory reducing the electrical load considerably should prove it. (Remove fuses A and C which supply the headlight, signals, tail light, brake light and combination meter). Monitoring the battery voltage under the increased load condition would also assist in proving this idea.

I completely agree MartiniRossy.

For me I simply avoid traffic. On back roads or on the track I have had no issues. Why? The revs are up so the battery stays charged, the bike is moving so the fan doesn't need to come on.

One other thing that might help would be to clean the fan motor... or to setup a pulse width modulator on the fan's power supply. With a small potentiometer you could drive the fan at 50% so you'd get some cooling with a lot less electrical draw.

I still agree - the best solution is an R/R swap. The F4i stator should be able to be made to fit... and the Shinden RR would handle the extra juice easily.

The final step would be to find a way to shim in a bigger battery. There is *some* extra room under the seat so some careful hacking and fabrication could be done to mount a slightly bigger battery.

Aside from the charging system problems I think these factors would exasperate the problem:

- riding in heavy traffic (low speed, low rpm)
- dirty radiator
- poor electrical connections on fan motor
- old coolant or improperly mixed coolant
- old battery
- running lean (runs hotter, needs the fan more - could be result of not tuning after installing an aftermarket pipe)

+100 on all that as well! Good idea with the pot too, I never thought about doing that!

changing the plug out on the R/R isnt hard either ;)

Thanks for the info gents. I'll start working through the maintenance issue while I look for an R/R. I can't wait to solve this thing. I'll make sure I post the progress. I do think its going to keep coming up for other people. I can find 6 posts about the same issue in the first two pages of the forum.

I will say that the fan on=bike off aspect of it has always felt like something electrical. I just don't have the diagnostic skill to track it down. The taking apart and putting back together, no problem. But I've always viewed people who are good with 12v systems as having tall, pointy hats and wands they wave over broken stuff that is then magically fixed. I swear I'll read some on 12v one of these days.

The fan will be on as long as the key is on... turn the key off. :D