Sudden throttle disengage

BitesWhenBitten

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Today while riding, I was doing about 70 on the expressway and the throttle suddenly quit working, was not shifting was not breaking couldn't hear any Rev when twisting the throttle either. Electrical control unit display stayed on and I watched my speed drop to about 50 as I started to make my way towards the side of the road to look at the bike. Before I even hit the rumble strips, yes I know it was before because I see the rubber mark on the yellow line, my front wheel started to wobble uncontrollably, and I eventually laid it down. On top of the insult that there is likely something wrong with the bike, I now get to replace the crankshaft cover which was entirely shredded. I'm curious if anybody else has had any similar experiences that may be able to shed light onto what the actual issue is. I would suspect the ECU, as I have had issues with the wiring to the display crunching and cutting off before, as well as a couple of other unexplained wobbling incidents, but not quite in this nature. Thank you.

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TownsendsFJR1300

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A little more detail please?

Did the engine DIE / stop running?

Is the throttle cable turning the throttle bodies?

Are you loosing ALL electrical power or just the engine stalled?

Kinda rare for the ECU to fail, but with the limited info posted, I would suspect your RED KILL SWITCH has a bad connection..

This thread shows, with pic's what happens when the KILL SWITCH fails:
http://www.600riders.com/forum/fz6-electrical/58255-kill-switch-problem.html

(Posted about your CCT cover already)


BTW, did you repair / find the electrical wire "crunching issue" and fix it?
 
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zixaq

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Depending on your exact riding geometry, tire condition, suspension settings, etc. it's not that unusual to have a little wobble at some speed while coasting. Mine used to do that around 45 mph, but new tires and some suspension tweaks resolved it. It's entirely possible that you were focused on the other problem or worried and gripping the bars a little too tight, which can turn a minor wobble into a tank slapper in a big hurry.

It does sound like your engine died due to an electrical malfunction, but as Townsend mentioned, ECU problems are very rare and you should assume it's NOT the ECU until you've checked everything else. Step one is that kill switch: Either give it a good cleaning or just short across it and see if the bike starts and runs okay
 

Motogiro

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:welcome: to out big family!Besides the kill switch or ignition switch and wiring (especially where the wires bend in the steering area) there might be a problem with the Throttle Position Sensor. Any error codes on your readout?

The front wobble should not occur unless there was a very bad condition in the road surface or you were hot n heavy under acceleration making the front light. Low front tire pressure with hard front brake might do the wobble. As already mentioned tire condition and steering geometry.

If you locked the rear you loose one of 2 gyroscopes and everything goes to a better possibility of unstable behavior.

Most important is you're on the forum and hopefully back on the bike asap. :)

Love that picture of you and Dad!
 
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BitesWhenBitten

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I will have to take a look at that thread.
The digital display stayed on through the whole incident.
The display cable only "crunched" on one trip, and I'm assuming that's what it was based on error codes and other forum posts. My intention was to find the wiring to move it from the pressure point if it kept occurring. When the cable crunched everything kept working, I just didn't have a display.
I kept rolling the throttle and getting zero response from the engine of any sort.
I have to get the new timing cover on it (shredded that, if I didn't mention), before I can do any further testing with the kill switch.


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BitesWhenBitten

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To be more specific: I'm not 100% certain the engine wasn't running. I wanted to look at my helmet video, but the SD card, of all things, flew out of its slot onto the road somewhere.
I know at a complete stop once before I laid it down (I saw a car at the last moment before takeoff and stopped with the bars bent), and the engine died without having to hit the kill switch. I assumed it was a safety feature.

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BitesWhenBitten

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How would I check if the cable is turning the bodies? That's not a term I've heard used before.

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BitesWhenBitten

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One thing I probably should have mentioned first, I had the bike lowered with a kit and via the forks by the same mechanics that sold me the bike.
Again, I know very little about the mechanics of bikes, I just enjoy them, so I'm not sure if that could be relevant to the wobbling.
I've had it wobble on a few occasions that didn't have any apparent explanation, but not as violent as this incident. I had always thought it probably had to do with the way I rode.

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BitesWhenBitten

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:welcome: to out big family!Besides the kill switch or ignition switch and wiring (especially where the wires bend in the steering area) there might be a problem with the Throttle Position Sensor. Any error codes on your readout?

The front wobble should not occur unless there was a very bad condition in the road surface or you were hot n heavy under acceleration making the front light. Low front tire pressure with hard front brake might do the wobble. As already mentioned tire condition and steering geometry.

If you locked the rear you loose one of 2 gyroscopes and everything goes to a better possibility of unstable behavior.

Most important is you're on the forum and hopefully back on the bike asap. :)

Love that picture of you and Dad!
I didn't get any error codes.


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BitesWhenBitten

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:welcome: to out big family!Besides the kill switch or ignition switch and wiring (especially where the wires bend in the steering area) there might be a problem with the Throttle Position Sensor. Any error codes on your readout?

The front wobble should not occur unless there was a very bad condition in the road surface or you were hot n heavy under acceleration making the front light. Low front tire pressure with hard front brake might do the wobble. As already mentioned tire condition and steering geometry.

If you locked the rear you loose one of 2 gyroscopes and everything goes to a better possibility of unstable behavior.

Most important is you're on the forum and hopefully back on the bike asap. :)

Love that picture of you and Dad!
I wasn't using any of the brakes either, I was just trying to glide to the side of the road and let the engine stall.
I had considered that maybe the throttle had kicked back in at the last second.
I wish I had the video for an objective view.

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BitesWhenBitten

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I apologize for not replying directly, I'm still getting used to the forum controls.

Thank you for the leads.

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BitesWhenBitten

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Saw the kill switch thread, when I can I will disassemble mine to see how bad it is.

But first, to cycle gear for a brand new helmet.

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TownsendsFJR1300

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How would I check if the cable is turning the bodies?

Look just under the left side of the fuel tank. You'll see a "disc" with TWO cables attached to it. One on top, one on the bottom.

One is the PULL (acceleration) cable, the other is a safety RETURN cable.

That disc, when turned (with the cables) opens and closes the throttle (and engine RPMs). If it doesn't move with the throttle movement, you have a broke cable (not likely)..

And your correct about the engine stopping when tipped over. There's a "Tip Over Switch" under the RS pod that kills the engine when you tip / fall over.
Nothing to re-set, just lift the bike up. If your curious, remove the RS pod, there will be a black rectangular unit that has "UP" printed on it...
 

Gary in NJ

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There's a lot going on in this thread...but I wanted to respond to one topic.

There are no circumstances where front end wobble is "normal" on an FZ6. If you are experiencing wobble, you have an underlying problem that needs to be solved. Typically wobble is caused by a tire that is under inflated or cupped, worn wheel bearings, loose axle, worn steering head bearings or poorly functioning suspension components (broken spring, low oil, wrong oil, poor damping). In your case, you have made suspension mods, which in and of themselves may be the root cause of instability. When forks are internally lowered (or raised in the triple clamps) the steering geometry (rake & trail) are also changed. At 25 degrees of rake and just 98mm of trail, the FZ6 already has an aggressive steering geometry. If the forks and shock on your bike have not been lowered proportionally you may have introduced a condition whereby the steering geometry is now inherently unstable. If that is the case you will need to install a steering damper.

I would have the maintenance items noted above inspected and confirmed to be in serviceable condition. If all checks out there, I would review the modifications to the suspension. Do you happen to know what was done to the suspension to lower the bike? Do you know how much travel has been reduced. Please don't tell me that after making suspension changes that the mechanic allowed you to ride off without setting static and race sag.
 

BitesWhenBitten

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Look just under the left side of the fuel tank. You'll see a "disc" with TWO cables attached to it. One on top, one on the bottom.

One is the PULL (acceleration) cable, the other is a safety RETURN cable.

That disc, when turned (with the cables) opens and closes the throttle (and engine RPMs). If it doesn't move with the throttle movement, you have a broke cable (not likely)..

And your correct about the engine stopping when tipped over. There's a "Tip Over Switch" under the RS pod that kills the engine when you tip / fall over.
Nothing to re-set, just lift the bike up. If your curious, remove the RS pod, there will be a black rectangular unit that has "UP" printed on it...
OK, based on everyone's response, I think it is likely I have a grimey kill switch shorting. But I will check this as well.

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BitesWhenBitten

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Plus 1 ^^^.

You SHOULDN'T have any de-cel wobble at all..

Worn tires and steering head bearings (loose / worn) are the biggest culprits..
I guess I need to look at the bearings, I had a brand new tire put on the bike when I bought it, the old tire had dry rot.
I normally don't have wobble while decelerating, just a handful of times. Which I guess I hadn't thought about it, but all have been while decelerating, lol.

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BitesWhenBitten

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There's a lot going on in this thread...but I wanted to respond to one topic.

There are no circumstances where front end wobble is "normal" on an FZ6. If you are experiencing wobble, you have an underlying problem that needs to be solved. Typically wobble is caused by a tire that is under inflated or cupped, worn wheel bearings, loose axle, worn steering head bearings or poorly functioning suspension components (broken spring, low oil, wrong oil, poor damping). In your case, you have made suspension mods, which in and of themselves may be the root cause of instability. When forks are internally lowered (or raised in the triple clamps) the steering geometry (rake & trail) are also changed. At 25 degrees of rake and just 98mm of trail, the FZ6 already has an aggressive steering geometry. If the forks and shock on your bike have not been lowered proportionally you may have introduced a condition whereby the steering geometry is now inherently unstable. If that is the case you will need to install a steering damper.

I would have the maintenance items noted above inspected and confirmed to be in serviceable condition. If all checks out there, I would review the modifications to the suspension. Do you happen to know what was done to the suspension to lower the bike? Do you know how much travel has been reduced. Please don't tell me that after making suspension changes that the mechanic allowed you to ride off without setting static and race sag.
Lol, um, maybe?
It's looking like I won't be taking the bike back to the same mechanic I bought it from.

We did a lowering kit off Amazon as well as a lowering by the forks. (not sure how to articulate what they did, though I watched. It seemed they loosened the forks in order to push them up)
If all else turns out well, I'll have them undo the fork lowering.
I've since regretted having it lowered for a number of reasons, primarily the pain it is to get on center stand first, and I've come to understand in riding other big bikes that I don't really need it anyhow.

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Motogiro

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Keep in mind that when the bike suspension height is changed you might modify the side stand. This may have been done already. The fact that you have front end wobble is the 1st thing you want to solve before getting back on your bike.

Dropping the front of the bike even 1/8 inch will increase what is termed "turn in" Too much turn in could result in wobble but as Gary has listed, there are many things that can attribute to that anomaly.
 

Gary in NJ

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Lol, um, maybe?
It's looking like I won't be taking the bike back to the same mechanic I bought it from.

We did a lowering kit off Amazon as well as a lowering by the forks. (not sure how to articulate what they did, though I watched. It seemed they loosened the forks in order to push them up)
If all else turns out well, I'll have them undo the fork lowering.
I've since regretted having it lowered for a number of reasons, primarily the pain it is to get on center stand first, and I've come to understand in riding other big bikes that I don't really need it anyhow.

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I'm not sure what a lowering kit on a the FZ6 would consist of. The FZ6 uses a linkless shock, so there aren't any traditional lowering links (nor should they be used because they change the ratio). Perhaps a shorter spring was installed. Then that begs the question - "what rate"?

Raising the forks in the triple clamps effectively decrease rake and trail. Rake is the effective steering head angle. On the FZ6 fork angle and steering head angle are one in the same. 25 degrees is already on the "sporty" side of things. As a point of reference, Standard bikes are typically in the range of 25 to 28 degrees, Cruisers are in the range of 30 to 35 degrees, and race bikes are 24-25 degrees. So you can see you really don't want your steering much faster then what Yamaha has already provided. Trail describes the stability of the steering as it relates to the rake. In the range of 100mm (4 inches) is fairly common for a standard and even sport bikes. The FZ6 is 98mm (3.78 inches) so it's once again on the sporty side of things.

By raising the forks you may have decreased rake (faster steering) and trail (less natural stability). I say "may have" because I don't know what was done to the shock, nor do I (or you) know the sag settings. I guess the point of the post is this; don't change things until you understand the effect of the change. If you don't NEED the suspension lowered (i.e. you can't properly touch the ground) - then don't do it. If you need the suspension lowered, and now you have an unstable steering geometry, than you need to address that through other means, such as a steering damper.

I would never ride a bike that makes me uncomfortable. Unpredictable handling is #1 on that list.
 
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