Katana 600 sudden stalls

[aggierider]

I have owned a katana for over two years now, and I love it. However over the past couple months I have been experiencing a problem which is getting degenerately worse, and I can't wait any longer to fix it. When driving, I will lose power suddenly and without warning. At first it happened under load. However during my last trip it was fine for the first half mile, then quickly got worse and worse to where the engine cut out every hundred yards. If anyone has had a similar problem please let me know (more detailed description and thoughts below)

More details on problem:
I have noticed that when the problem wasn’t as bad, I could simply back off the throttle and it would be fine again in a couple seconds. Now I need to completely pull in the clutch so that the engine doesn’t shut down. When I cannot save it, it would backfire upon starting again. I think this is not a part of the problem, simply a symptom of the engine stopping while the bike is operating at relatively high RPMs. I think that there could be several things going wrong here:

1. The first thing which I know is a problem is the kickstand bouncing and setting off the safety interlock circuit. However I think this is not the main problem as the motorcycle would always turn off. Instead I am able to “save” the motor from being killed by pulling in the clutch (note that this is 5th gear and on the highway).
2. The fuel filter is clogged. Finger’s crossed that this ends up being the problem
3. The carbs are clogged or are experiencing some other type of problem. The fact that this has been getting worse and worse makes me believe that is this or the previous problem.
4. The Pulse generator coils are failing. I have mentally ruled out this possibility as the constant progressive nature of the problems reoccurrence doesn't suggest an electrical problem.

Any help I can get before I strip it this weekend or take it into the shop would be much appreciated!

[RossW]

1, 2, and 3 are quick and easy. Try bypassing the side stand safety switch, if the problem goes away, there's your culprit. You should probably replace the fuel filter and do a thorough carb cleaning regardless. Also make sure none of your fuel lines are pinched.

[Kreylyn]

My first guess would be electrical.

Check the sidestand switch, clutch switch, and check all your main power connections to make sure they are not corroded or loose. Apply dielectric grease as nessasary after cleaning them all.

Krey

[JayBell]

gradual loss of power may also indicate a cracked or broken vac line to the petcock, or leaky petcock diaphram.... especially since if you back off the throttle it smooths out.

if the vac line is broken or restricted, it may not be allowing enough vac pressure to keep the fuel flowing.

your bike may literally be running out of gas due to draining the bowls at higher RPMs.

next time it happens, switch the fuel to PRI and see if it solves it.

if it does, check the petcock and associated vacuum lines, and yeah, check replace the fuel filter.
this doesn't sound electrical to me, sounds fuel starvation related.

same behavior on my 01 750 when the vac line got plugged.

also, telling us the YEAR of your bike may lead to additional troubleshooting help.

[aggierider]

All,

Sounds advice from everyone. I will work on it this weekend. My bike is a 1999.

[smokintalon]

had a very very similar problem a few days ago on mine. Tracked it down to a bad connection in the plug wires. I pulled the whole ignition system and bench tested everything. Checked the wires with an ohm meter, and two of the four were hit and miss on the meter. Separated the boots from the wires. The wires all ohmed out at 0. The boots all ohmed out at 9 to 11 ohms. So, I cut about 1/4" off the ends of the "bad" wires, put it back together and she'll drag you around like a scalded dog.

I would clean or replace the fuel filter anyway. Wouldn't hurt. Make sure you road test it close to home everytime you change something and anytime you work on it. This will let you know if what you just did actually did anything at all, or was the wrong thing to do. Check your wires too. With the boots on, they should ohm out around 10 (+/- 1) ohms. 5 minutes to check. Just don't break the plastic clips on the ends of the wires!!!

[burningmetalmaniac]

My experience says ignition coils or bad wires as smokin' said. Usually when coils go bad, they start going when hot and when wires and plugs go bad, it starts under a load.
my 2cents

[aggierider]

Answer

Hey everyone, thanks for your input. I ended up replacing the fuel filter and draining the carbs. I also did some other things, but I think that one of these to fixed the problem. I think it was the filter since it was pretty clogged when I pulled it out. Again, thanks for all of the advice!

[SuzukiJoeDirt]

I have owned a katana for over two years now, and I love it. However over the past couple months I have been experiencing a problem which is getting degenerately worse, and I can't wait any longer to fix it. When driving, I will lose power suddenly and without warning. At first it happened under load. However during my last trip it was fine for the first half mile, then quickly got worse and worse to where the engine cut out every hundred yards. If anyone has had a similar problem please let me know (more detailed description and thoughts below)

More details on problem:
I have noticed that when the problem wasn’t as bad, I could simply back off the throttle and it would be fine again in a couple seconds. Now I need to completely pull in the clutch so that the engine doesn’t shut down. When I cannot save it, it would backfire upon starting again. I think this is not a part of the problem, simply a symptom of the engine stopping while the bike is operating at relatively high RPMs. I think that there could be several things going wrong here:

1. The first thing which I know is a problem is the kickstand bouncing and setting off the safety interlock circuit. However I think this is not the main problem as the motorcycle would always turn off. Instead I am able to “save” the motor from being killed by pulling in the clutch (note that this is 5th gear and on the highway).
2. The fuel filter is clogged. Finger’s crossed that this ends up being the problem
3. The carbs are clogged or are experiencing some other type of problem. The fact that this has been getting worse and worse makes me believe that is this or the previous problem.
4. The Pulse generator coils are failing. I have mentally ruled out this possibility as the constant progressive nature of the problems reoccurrence doesn't suggest an electrical problem.

Any help I can get before I strip it this weekend or take it into the shop would be much appreciated!

I'm not saying this is it but I had a similar problem with my Kat 1100. Only it would do it when ever it was like really wet and rainy outside. I would have moister in my spark plug holes and I wouldn't be able to get spark. When I figured out the issue I put some dielectric grease on them heavily and every other connection open to moisture. Haven't had an issue since.

[smokintalon]

its funny how you can have 20 bikes, all the same, and all with the exact same symptoms, but they all turn out to be something different! Gotta love it!

Glad you got it fixed though!