Poor running, losing rpm

[matthew]

I bought my bandit about 3 months ago, not running.  I cleaned the carbs, changed fluids and filters, changed the plugs, and fixed the ignitor.  I've finally gotten it running but not very well and i'm stumped.

It's fairly hard to start, but once it's running and warmed up a bit, it idles fairly well with no choke, although it dies occasionally.  The idle is not very clean and surges up and down some.

When I rev the thottle it will rev responsively and drop back down to an idle.  However, if I turn the thottle and hold it at around 8K and do not move my hand it will hold that rpm for a second and start dying down.  If I try to give it any more thottle once it starts dying it will make it die faster.  

If I let go of the throttle it will drop back down to an idle and let me rev on it once again after a few seconds.

Fuel flow from the tank to the carbs seems to be good with no air in the line.  Spark seems to be good.

The only other thing I can think of is that the carbs have not been balanced since they were cleaned.  I did have to remove the #4 carb for some repairs so i'm sure they're not perfectly synced.  I have some gauges on the way but I have my doubts as to whether that's causing this running problem.  I'm sure the balance will help out the idle surging but I wouldn't think it would make that big of a difference at the higher rpm. Any ideas?

[matthew]

Well, i answered my own question today.  The solution to my high-rpm problems was a new battery.  As best as I can figure, the ignitor wasn't getting a good signal.  

Now if I can just get my idle problems solved I'll be in business.  Right now it's usually hard to start but sometimes pops right on.  Once it's running, it won't idle under 4K without dying and is still hard to keep running anyway.  I did a significant bit of tweaking on the idle mix to get it as far as it is.  I'm thinking the mix is still not right or possibly my idle jets are just worn and it's time for new ones.

[nlr126]

So you're saying that a new battery helped your bike run better at higher RPM?  I have a similar problem – my bike is a little tough starting, and always requires fiddling with the idle adjustment.  Sometimes it just starts to sputter, and I have to hold the throttle open once it’s off of choke to prevent it from dying.  And once I get it running, it’s ok until I hit high RPMs.  On the highway, it just starts cutting out after a while to the point where it feels like I’m running out of gas and it won’t rev above about 9k RPMs and eventually stalls the next time I pull in the clutch.  

I have discovered that there’s some gas in my oil, so a battery is likely not my only problem, but I’ve checked everything in the electrical system (by parts swapping with my brothers 92 B4) and have had the same consistent problem.  

Does this sound similar to the problem you rectified with a battery?

Nevin

[magicGoose]

Hey guys,
I had symptoms similar to Nevin's, bike would die at idle at stop lights, and would cut out at high RPMs like it was running out of fuel. My problem was the Reg/Rect. I would suggest going through the tests in the service manual to be sure your charging system is working OK. Mine looked good at idle, but when RPM was increased the voltage would climb quickly, and then suddenly cut out.
Steve