Katana needs help...

[kiwiman555]

My Katana stopped working right before winter started up. I found out the voltage regulator/rectifier was busted so I installed a "new" from e-bay alternator and got a new battery. After I put those in I hit the starter button and hear a bang. I figure I should have opened the engine up to see what the hell the noise was but I didn't feel like it, it still turned over.

After some cranking with the choke on (or Enricher in this case) it started and revved up to about 5K. It seemed to lack power when I fiddled with the throttle and sounded very funny. Then when I took the choke off, it immediately died. So, I can start it with the choke and rev it, but when the choke is off it's like it doesn't have any fuel at all.

I had the same fuel sitting in the carbs and the tank for about a month, I changed the fuel in the tank today and assumed the fuel in the carbs would have evaporated by now.

Here's the million dollar question. I am opening up the carbs right after I write this, to check the float bowl area for crud that I will hopefully find and solve my problems; But other than that, what else could be wrong? I'm assuming it's a fueling problem but could it be something else?

Thanks in advance for the help.

~Rick

[kiwiman555]

I forgot to mention, the float bowls had gas in them after I took them off.

I just opened up the first carburetor and found it clean as a whistle. Just as I had feared and assumed.

What, pray tell, could possibly be wrong?!?!?! AAHHHH!!!

I'll continue to take apart the carbs and make sure they're all pretty. Thanks peeps!

[The CyberPoet]

Well, a bang is normally a result of there being too little or too much fuel in the cylinder to fire (and it subsequently firing in the exhaust when another cylinder dumps a sucessful ignition). Clogged jets, or clogged air intake (filter, passage) could play into it, as could bad spark on a cylinder. Clean out the airbox while you're at it...

Are you getting spark in all four cylinders?
Have you checked your signal generator, and your charging/static voltages?
My advice: start by changing plugs, cleaning out the carbs (which you're doing already) and then checking the voltage at the battery with the bike off and again with it running...

Post what you find!

Good Luck!
=-= The CyberPoet

[kiwiman555]

Well, I got it running and took it around the block. It goes fine in the upper RPMs, still sounds a bit funky, kind of rumbly and rough. When I pull in the clutch while riding the Tach needle swings down and putters around idle for a second or two then stops. I haven't checked the signal generator, that's the thing on the right side of the crankshaft right?

The carbs are clean, I put some techron in there just in case. In the gas I mean.

I have K&N pod filters that were cleaned not more than a month ago. I wasn't running with the filters on when I went around the block though. In the garage when I got it started I looked at the slides in the carbs, when I gave it throttle off of idle the slides kind of jiggled up and down as if the cylinder wasn't firing for a few revs then they opened up all the way when it revved cleanly. Kind of neat looking, but most likely bad for it.

As for voltages:
Off: 12.6 (brand new battery)
Idle: ~14V
Revving: Just barely hits 15V, usually around 14.5V

Another thing I noticed is when it got up to temperature it "something"-fired when decelerating. not sure if it was out the exhaust or the carbs (I didn't want to stick my head or hands down to check). but it sounded bubbly like a racecar. When I got back on the throttle in the higher RPMs it was very responsive, no lag at all.

I'm going to go check the sparks now. They were weak before I replaced the Battery and Alternator, so they may still be weak now. I need a big fat blue spark right?

I'll check the signal generator too. I'm assuming it's not drenched in oil, at least I hope it isn't designed to, I just changed the oil!

I have some early model GSX-R600 ignition coils around here somewhere too, so I'll try using them if the spark is weak. Unless that's horrible then someone yell at me quick.


I'm hoping I didn't forget anything. I apologise for the random thought order and thank you very much for the help!

[The CyberPoet]

Well, I got it running and took it around the block. It goes fine in the upper RPMs, still sounds a bit funky, kind of rumbly and rough. When I pull in the clutch while riding the Tach needle swings down and putters around idle for a second or two then stops...
I wasn't running with the filters on when I went around the block though. In the garage when I got it started I looked at the slides in the carbs, when I gave it throttle off of idle the slides kind of jiggled up and down as if the cylinder wasn't firing for a few revs then they opened up all the way when it revved cleanly.

Based on your answers, vacuum issues are causing the slides to jiggle (not unusual at idle with the filtration off). The after-fire was from it going too lean at idle. Did you rejet when you put in the K&N filters? You can forget the signal generator -- given what you said, that's no long an issue.

Basically, it's down to three possible issues (by order of likeliness):

1. Idle circuit needs enrichment or is partially blocked (dirty). Upping the pilot screws settings usually should resolve it, but if you changed filtration without rejetting, then it may take more than just an extra rotation on the pilot screws.

2. Vacuum leak somewhere in the intake stream, like a poorly capped carb sync nipple.

3. Bad (fouled) spark plugs.

Cheers
=-= The CyberPoet

[kiwiman555]

WOO HOOO!!!!!!!!

IT WORKS!!!!!!

weak spark. I put in the other ignition coils and it started right up!

this is awesome. Time to go ride around all day long.

Thanks for your help Cyber!