We had a customer with a GSX1200S Inazuma 1200 oil-cooled Katana that’s been running for 200,000 kilometers. They came in for an oil change on two bikes.
I said, “Hey, let me give your GSX1200S a one-touch start too,” and applied the usual fix, but…
The image is for reference only. (Not this particular bike.)
Most owners of these bikes know the quirks well, so there’s basically no starting problem. However, if you don’t know about it, you’ll find yourself in a slightly awkward situation.
Now, this rough starting issue comes in about two patterns.
• Repeatedly toggling the main key ON/OFF makes it worse.
• Using the kill switch ON/OFF makes it worse.
When you hear this, you think, “Wait, really?”
You might say, “Well, you don’t toggle it that often anyway,” but…
For example, turning off with the kill switch at a red light, then turning off with the main key—that’s when it gets rough.
To begin with, the Inazuma 1200 has a resistor in the main key. The Katana’s main key doesn’t have a resistor, so we need to add a 100Ω resistor afterward. (Of course, it’s already installed.)
But rough starting still happens. We know the cause, but we still don’t understand the reason—it’s a puzzling situation.
*Image is for reference only.
This GSX1200S has a Watanabe full-power kit installed.
The main harness was recently replaced with a genuine GSX1200 (Inazuma 1200) harness.
Even after the harness and Watanabe swap, this bike still had extremely poor starting, just like before. (It’s fine as long as you don’t use the kill switch.)
I’ve been going on for a while, but I added the fix to this situation, and…
“No change”—absolutely no change at all. (Bit of a shock.)
Since I’ve learned a painful lesson recently, there’s an easy way to investigate.
• Temporarily swap the main key cylinder with one from an Inazuma or similar.
• Swap the Watanabe unit.
That’s it.
The result: a Watanabe unit over 10 years old was dragging things down. As Watanabe units age, their versions improve, so in this case, the only option was to replace the unit—a situation we found ourselves in. (We didn’t replace it, though.)
