93 Katana 600 low power, bad throttle response

[phatality]

Hello everybody, I am new to this forum, so please be kind.

I have a stock 93 katana 600 that I have been happily riding for a year or so now. Up until this spring, it has been running great.

This spring I have taken it out of storage and gone through a couple tanks of gas with no issue. One day I rode it to work and the bike was way down on power. The throttle was slow to react and it didn't sound quite right either.

In light of this issue, I changed the spark plugs since they haven't been changed in a while. This seemed to have solved the problem. The next day I was out for a ride, when I got caught in a thunderstorm. I slowed way down until the storm passed. When I went to accelerate again, I had the same problem I had a few days earlier (low power, bad throttle response, not quite right sound)!

Since then, I have reexamined the plugs. They were black and carboned up, but it just wiped off. I have also replaced the plug boots on the wires. This had no effect on the running condition.

Tonight I plan to check voltage on the battery, and I am also currently running some carb cleaner through the gas tank.

I am currently trying to determine if the problem is spark or fuel.

Any suggestions are greatly appreciated.

Sorry for the lengthly first post.

- Brett
Blue? 93 Suzuki Katana

[87gsxrnut]

Brett,

See the '88 post below. Sounds like your carbs might need a good cleaning.

- Nut

[smarvel]

Originally Posted by phatality

Hello everybody, I am new to this forum, so please be kind.

I have a stock 93 katana 600 that I have been happily riding for a year or so now. Up until this spring, it has been running great.

This spring I have taken it out of storage and gone through a couple tanks of gas with no issue. One day I rode it to work and the bike was way down on power. The throttle was slow to react and it didn't sound quite right either.

In light of this issue, I changed the spark plugs since they haven't been changed in a while. This seemed to have solved the problem. The next day I was out for a ride, when I got caught in a thunderstorm. I slowed way down until the storm passed. When I went to accelerate again, I had the same problem I had a few days earlier (low power, bad throttle response, not quite right sound)!

Since then, I have reexamined the plugs. They were black and carboned up, but it just wiped off. I have also replaced the plug boots on the wires. This had no effect on the running condition.

Tonight I plan to check voltage on the battery, and I am also currently running some carb cleaner through the gas tank.

I am currently trying to determine if the problem is spark or fuel.

Any suggestions are greatly appreciated.

Sorry for the lengthly first post.

- Brett
Blue? 93 Suzuki Katana

[smarvel]

Considering that I am new to the ol forum thing. Brett, just wanted to seee if you had a good resolution to your "wet" katana. we have same pro lem.

smarvel
jamesstevenmarvel@cox.net

[phatality]

Update:

I dissassembled everything again and rechecked the plugs. This time plugs 1 and 3 were wet with gas. I am assuming that it is not firing on those cylinders.

I went throught the diagnosic procedure layed out in my clymer manual for testing the ignition system. According to one of the tests, both of my coils are bad. The test indicates that I test the resistance between the spark plug leads with the spark plug caps (boots?) attached. If the resistance is not within a specified range, then the coil needs to be replaced.

Just for fun, I tested the resistance between the leads with the plug boots off, and the resistance is now within the specified range. I know the plug boots are not a fault, because I replaced them and the new ones are identical to the old ones. That and their resistance tests to what is stamped on the side of them.

The thing that puzzles me is, how can both coils die at nearly the exact same time, in the exact same way and both exhibit the exact same resistance between their plug leads (with or without plug boots)? I would think that one would be different from the other in some way if one or both were bad.

Anyway, at the moment, I am going to assume that both my coils are bad and attempt to find a known good coil to test and see if the resistance is the same as mine.

If anybody can shed any more light or suggestions, it is most appreciated.

- Brett

[87gsxrnut]

Check your crank trigger and also your connections to the CDI box. Also, check the CDI box if you can. Sometimes a broken magnet on a crank trigger can cause all kinds of headaches.

- Nut

[smarvel]

Originally Posted by phatality

Update:

I dissassembled everything again and rechecked the plugs. This time plugs 1 and 3 were wet with gas. I am assuming that it is not firing on those cylinders.

I went throught the diagnosic procedure layed out in my clymer manual for testing the ignition system. According to one of the tests, both of my coils are bad. The test indicates that I test the resistance between the spark plug leads with the spark plug caps (boots?) attached. If the resistance is not within a specified range, then the coil needs to be replaced.

Just for fun, I tested the resistance between the leads with the plug boots off, and the resistance is now within the specified range. I know the plug boots are not a fault, because I replaced them and the new ones are identical to the old ones. That and their resistance tests to what is stamped on the side of them.

The thing that puzzles me is, how can both coils die at nearly the exact same time, in the exact same way and both exhibit the exact same resistance between their plug leads (with or without plug boots)? I would think that one would be different from the other in some way if one or both were bad.

Anyway, at the moment, I am going to assume that both my coils are bad and attempt to find a known good coil to test and see if the resistance is the same as mine.

If anybody can shed any more light or suggestions, it is most appreciated.

- Brett

Hey Brett, we took my sons Katana to a first class place today, Tulsa Cycle Supply, these guys are full time mechanics, owners of the high performance shop and make up the local race team. Serious riders but great guys. Not like a dealership for sure. Sure enough, first thing they did was lightly pull on the coil wires and one of them came right out. Anyway, they are running additional diag on it but we feel a lot better about my son's purchase now. As soon as we get resolution I will post and pm you as well. Thanks to all for being such a great community!!

[smarvel]

Originally Posted by 87gsxrnut

Check your crank trigger and also your connections to the CDI box. Also, check the CDI box if you can. Sometimes a broken magnet on a crank trigger can cause all kinds of headaches.

- Nut

Dear 87 gsxrnut, what exactly is a crank trigger and a cdi box. sorry for such a dumb question but sure are tryin to learn. thanks buddy

[smarvel]

Brett, smarvel here from Broken Arrow, Oklahoma. We replaced both coils on my sons 93 Katana 600 and it completely fixed the problem. Runs like a new bike. thought I would let you know. good luck