[Guest]

I have a 93 katana with about 8K miles and it sputters and misfires VERY badly at about 5.8K-8K RPM like cruising at 70mph you almost have to give full throttle to maintain/gain speed. It also misfires/sputters from 2K-3.5K and barely idles/cuts off alot. But it runs perfect between 4K-5.5K rpm and above 8.5K rpm. The previous owner told me that the carbs had been rebuilt/rejetted, and it does seem to run rich like poring out black smoke at full throttle. Does anyone Have any Ideas :?: :?:

 

[gsxrjeffro]

1. pull your plugs and see if any of them look bad... 2. it might be a bad coil and wire as well.... just a guess and a couple places to start

 

[greatzippy]

I'm not going to say my answer is correct but I had a similar problem with a 94 Pontiac Grand Am I had. When I got up to high speeds, around 70+, the entire car would shake and sputter. Over time the car started doing it around 60 .... then 50.
Anyway, I checked the plugs and the ignition coils ... everything was fine.
However, one of the plug wires was damaged at the boot portion connecting to the plug. This was causeing sparks for one and making the plug misfire like crazy.

It's the same as gsxrjeffro suggested. The plugs and wires are the easiest places to start looking.

 

[Guest]

Thanks, I'll start with that.

 

[The Chad]

sounds like a wire problem to me to, it's to, all over the board to be much elts.

 

[Guest]

Thanks for everyone's help, is there a certain brand of plugs or wires that are the best that I should look for?

 

[87gsxrnut]

I've used NGK plugs for years. I think the dual-electrode JR9C plug will work in that bike. I prefer them because they give a more efficient burn of the fuel. All my racebikes have them. But, the stock NGK plugs will work fine too.

Get the stock coil/wires if you can find them, unless you want to upgrade the ignition system. Stock stuff is plentiful and cheap used. I am troubleshooting an '82 Honda Magna w/the same issues. Looks to be a plug wire on that bike too. I just got a CDI and coils/wires off eBay for next to nothing. Hopefully have it finished tonight.

- Nut

 

[Guest]

Thanks, I went to the bike shop, they gave me the NGK DR8ES-L plugs, Anyone know what they should be gapped to :?:

 

[cr25ovet]

NGK DR8ES-L (the others) - gap 0.6-0.7 mm (0.024-0.028 in)
http://www.katanacentral.co.uk/themodels/gsx1100s/specs.asp

 

[Guest]

Oil Change

I was also trying to change the oil today, Do you really have to take off the headers EVERY time you change the oil in a katana? On mine it's impossible to get the filter off/on otherwise!

 

[Guest]

Put the new plugs (gapped .026) in today and now it finally runs perfect! I also took off the stock air box and put the k&n filters on.... definitely feels a little stronger. Thanks for everyone's help