[No Worries]

I was reading the "Tech Q&A" section in the February, 2004 issue of Rider Magazine and found a question about fouled plugs on a Katana. The bike in question is a 2002 600, but might apply to the 750 and other years.

The rider had dry black plugs, but the float level was correct, the jets were correct and tight, and the float needles and seats were perfect. With only 2,000 miles on the bike, he changed the plugs and they fouled again. What was the problem?

The Mikuni carbs on the Katana use plastic float needle seats that are pressed in with a sealing O-ring. The O-ring shrinks from heat allowing gas to bypass the needle, seat and float. It's not a gusher, but it allows excess gas to foul the plugs. So check those O-rings if you have this problem.

 

[jeeps84]

:readng: Thanks N W. :dthumb:
I've been working on friends 2000 Kat 600 that has the same issue. I've cleaned and adjusted everything so many times I told him to take it some where else. I had no luck at all. What really confused me was, It didn't foul the same plug every time.

 

[No Worries]

: What really confused me was, It didn't foul the same plug every time.

I also had the problem of different plugs fouling on my 79 GS 1000. Dirt would get between the float needle and seat of one carb, and then overflow the float. But other plugs also fouled.

All the carbs float chambers are hooked together and then use two end vents. The gas from the flooded carb traveled to the other carbs through the connections. But years ago I had added a clear inline fuel filter near the petcock and still had chunks of dirt clogging the float needle. Solution: I replaced the old fuel line which was flaking off pieces of rubber inside.

 

[Gas Man]

NW...you are a constant sourse of good info!