1989 Katana 1100 misfire?

[masx]

Not sure if I have a spark plug problem on my 1989 Kat 1100. It was running great during a short ride and when I parked it for a few days, it started but with what seemed to be a misfire or erratic fire. I rode for a bit and tried to clear a fouled plug but it didn't help. It sort of feels like one plug stopped, although no like a fouled plug, more like one just quit. I got it home and parked it. My plugs were changed in 2017. They are JR9Bs. Could one plug just go bad that quickly?
Brand new Yuasa battery. Do I have an electrical problem somewhere else. What should I look for? Could it be a fuse? A loose wire somewhere?
I have not tried to look yet because I just spent a lot of money on wheel bearings, new tires, sprockets and chain and am afraid because I am broke! lol
What seems odd to me is that the last ride it had full power and ran like gangbusters.
Thanks for any input and ideas.
Bob

(I hope people are still coming here because it seems like most post are years old.)

[masx]

Addition to problem - I put in new plugs. I found one lead loose while installing but installed all new ones anyway. My old plugs were not fouled at all and only a nice even grey color. Then started it and it ran but didn't ride it.
Then a day later went to ride it, it started ok and idled at speed. Then put it in gear and started to move slowly in 1st gear and it seemed to misfire again. Got about 100 feet and it was terribly misfiring and had to walk it back home. Than it would not start at all.
So I have no idea what to look for from here. It has to be electrical because it was running beautifully before.
I hope to get an answer here just suggestions.
Thanks anyone.
Bob

[jetta90]

Hello masx - I think in the past there used to be considerably more people on this forum. Life as a way of getting in the way sometimes - it's unfortunate but can't be helped.

Related to your running issue on the 1100 - it would be good to know what kind of mileage is on the bike? Have you owned it for some time? Do you know the history?
Has it been sitting for a long time?

I am in BC as well and have an 88 - 1100 Katana that I am debating on whether or not it merits resuscitating.

[masx]

Hi, Yes I bought the bike new in 1990. This happened ONE day after riding it. Not stored. 120,000 km on it. I now think it is a fuel feed problem.
As to your 88, 1100 Katana, if you can afford it and get it going well, there is not a better bike to ride for power and comfort. I had so many great Duffy Lake rides where it excels. Be aware that parts are still available because most are the same to 1993 I think. But it takes awhile to get them. (if you can shake them up a bit) lol If you can do work yourself, all the better.