2004 Yamaha fz6 - throttle issue

[Alvito]

Hi,

I was riding a couple weeks ago and while passing a truck with the throttle pinned, the bike locked itself into the 16,000rpm range. It went full tilt for a couple seconds before I pulled the clutch back in and hit the kill engine switch.

Once parked on the shoulder, I tested the throttle and it was springing back into place. Once the bike cooled down. I restarted it and it immediately went full RPMs. I shut down the bike and had it towed home.

In April, I had a private driveway mechanic do a valve clearance adjustment, spark plugs, cam chain, oil change, and brake fluid flush. I rode the bike 2 or 3 times before the RPMs started to run away.

Google gemini thinks the throttle cable is pinched or twisted in a way which locks it into the wide open position.

It also suggests that there may be unmetered air getting into the engine.

I wasn't comfortable doing the valve clearance job. I'm debating if I should try to dig into it and see if I can reseat the throttle cable/find an obvious air leak.

Any thoughts and encouragement would be appreciated. As well as a shop near Lawrence and Victoria park that could help tow the bike and sort it out for me.

Side note: the tow operater had the kickstand down while strapping the bike down. I was not a fan of that. The kick stand feels "loose" when engageling it. Should I get a shop to check this out too?

 

[GreyGhost]

Rev limiter while in gear should not be an air leak. While a leak can increase revs in neutral, most leaks are small and dont unleash substantial hp.

I would be focusing on the throttle cables. Your second paragraph where throttle tube was springing back and bike went to redline is strange. I'd have to look at diagrams to figure that one out. Can the cables move without moving the actual throttle?

This thread seems similar:

Stuck Throttle, not cables or grip.

'07 FZ6 I know what you're thinking, yet another stuck throttle thread. Just lube the cables! I've dissembled the grip & cable housing, everything's moving freely there (well, the grip needs some TLC, 10 years of being an "outside bike", but it still turns freely with the cables...

www.600riders.com

 

[Mad Mike]

I’ve seen that happen on an FJR, it was corrosion on the rod actuating the throttle body.

Here’s what I’d do.

1. Disconnect both the cables from the throttle body and check they are a) routed correctly, and b) smooth back and forth. If they are not smooth, disassemble the throttle, make sure it’s not binding, then test each cable for smoothness. If anything is binding, don’t lube - replace.

2. With cables off, actuate the throttle body rod. It should be smooth and it should snap back forcefully. If it doesn’t, shoot some penetrating fluid (I like Zep or PB blaster over WD40). Work the shaft until it snaps back every time.

3. Check for correct routing. Sharp radius on cables can cause binding even when they test smooth.

Don’t do any of these tests when the engine is running. Once you’re certain all is smooth, then run the motor for a final test

Air leak is not going to cause a WOT condition, it might cause a slow return to idle, rough idle, and sputter or surging on acceleration - and of course engine damage over time from running lean.

 

[Alvito]

Rev limiter while in gear should not be an air leak. While a leak can increase revs in neutral, most leaks are small and dont unleash substantial hp.

I would be focusing on the throttle cables. Your second paragraph where throttle tube was springing back and bike went to redline is strange. I'd have to look at diagrams to figure that one out. Can the cables move without moving the actual throttle?

This thread seems similar:

Stuck Throttle, not cables or grip.

'07 FZ6 I know what you're thinking, yet another stuck throttle thread. Just lube the cables! I've dissembled the grip & cable housing, everything's moving freely there (well, the grip needs some TLC, 10 years of being an "outside bike", but it still turns freely with the cables...

www.600riders.com

Yeah. Throttle tube springs back. Is it possible for the throttle cable to open and get stuck open, but still allow the return cable to put the throttle tube back in place?