Like it is not getting enough fuel, so I pulled the tank and fuel filter, they feed enough fuel no problem there. ran it with a small tank directly to carbs, runs good when cold but starts to cut out when temperature is about halfway, fan is on. Pulled one sparkplug, it's black, can the plugs cause this behavior? or does something else get hot so there is no spark?
Thanks

 

Mine has been doing this the last couple of days as well. I'm thinking either spark plugs or a fuel issue. It only happens to me between 5K-7K RPMs under mild to moderate acceleration. I'd like to hear other input as well.

 

Just talked to a Honda tech and since it happens when it's hot he seems to think electrical, specifically coil or pulse generator. I just tried to reproduce the problem while not moving with the tank off but off course it didn't do it.
It seems only diagnosable when the problem is there when it is very hot i guess.

 

Does anyone else have any input on this?

 

Black plugs is a problem because it means they're fouled. Black is an indication the A/F mixture is too fat and needs to be leaned out. The color you're looking for is a tanish color. Is there a jet kit installed? Does the stalling happen when you come to a stop or is it when attempting to get high RPMs? This could be an electircal issue, but you'll need to replicate the conditions... hot. If you have a multi meter, let the bike idle and get things hot. At this point, disconnect the pulse generator (2 pin red plug next to battery) and turn the bike over with the test probes in the pulse generator connector (White/Yellow + / Yellow - ). You should be looking for a reading no lower than .7 V. I had a pulse generator with low output (.35 V) on my 600 RR and wouldn't start. Post your results and we can go from there. By the way. While things are hot, test the voltage going into the battery with the RPMs around 4500. Your voltage should be 13 to 15 volts. I've had RRs that work just fine when cold and then crap out once they get hot.

 

Thanks for that , here is where I am , pulled all plugs this morning and 1 and 2 were blackish, 3 and 4 were tannish, replaced all plugs and cannot replicate the problem whith a hot bike fan going. So I hope that was all, I will do the other measurements next time I take the seat off.
Thanks

 

Spoke too soon, after the hot bike sat for 30 minutes He started it to go to school and the same problem appeared.
Yes it has a jet kit, carbs were rebuilt last december, new fuel lines and filter, bypassed fuel pump. I will take voltage measurements later.

 

Thanks, once I have time later this week I'll get into it and check things out. Mine idles just fine at any temp, but above a water temp of about 160deg, it has problems above 5000 rpms or so. It is hard to tell because of the engine speed but it seems to be fine above 8000 at any temp as well. That's why I'm confused about what it could be.
Thanks again and I'll report back later.

 

What stage of kit did you go to? After the carbs were rebuilt, were they synced? Why is the fuel pump being bypassed?

 

I am not sure, and can't remember the numbers it was in there when I got it, the PO gave up on this bike and I got it for $600 for my son, I just remembered he told me about the hot starting running problem, we just didn't notice it in the winter and it ran fine for months now.
I did not sync the carbs, it is on the list.
Pump was bypassed because of a faulty relay, I ordered a used one and bypassed it in the mean time to get it running, but never put it back because there was no problem.