2014 motor cut out over large jump...

That's the bad news... The good news is, aside from some deep bruising and overall soreness, I'll be fine.

 

Question is, why did it shut off? Here is what happened...

 

2nd moto (with a short 1st moto's gas missing from my initial full tank) and the track is in great shape. I hit a triple that is pretty good sized, but built well and is pretty easy to do. I have hit it a thousand times so I don't believe I did anything out of the ordinary. I was leaned over the front of the bike just before landing, I go to give it gas and it dies. It happened so fast and so close to the landing that there was nothing I could do but tuck and roll. 

 

Considering what had just happened, I was able to spring to my feet relatively quickly and picked up the bike. After I pushed it off the track and getting my bearings back, it fired right up.

 

Not sure if they are related, but here are a few things to consider...

 

- My clutch is slipping a little and with a fresh, softish track, it may have been running a little warm. Could I have vapor locked the fuel?

- I have heard all sorts of issues with the kill switches on these late model Yamahas. Could it be shorting out?

- Most of the larger jumps had big g-outs before the faces so you would almost be unloading the suspension and slamming the face to get over them. Does something like this matter with FI?

 

I am leaning towards a possible faulty kill switch, but curious if the other items would be a concern as well. I DO NOT want this to be in my head so I am really hoping for some wisdom on this. 

The bars took the brunt of it. I'd say we both made it out pretty lucky...

 

 

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My 2011 started cutting out when I lifted the front to get over a tree stump or lifting the wheel over whoops, or jumping, never did it on flat ground,

It would not do it with a full tank only half a tank of gas or less

Replaced the fuel pump and it was fixed, bike had low hours on it

I have nothing to add but to say glad your alright...

Tip over sensor? I know nothing about the 14 yz450 but have read other models if the sensor goes bad it causes cut out in various situations?

I had to replace my kill switch at 15 hours. First time ever on a bike. I have the '14 YZ 450 as well.

Riding my bike on weds with the throttle body mod. Helps with throttle response.... Should be interesting.

I'm not familiar with the tip over sensor and my bike often stays running when it is tipped over. What does it do?

 

motoxjeff, did you replace your kill switch because it was cutting out? What made you replace it?

I'm not familiar with the tip over sensor and my bike often stays running when it is tipped over. What does it do?

motoxjeff, did you replace your kill switch because it was cutting out? What made you replace it?

As far as I know about them is from my experience with my brothers 2010 artic cat 700 atv. It's pretty much a level that sense when the bike/atv is past a certain angle so it cuts power to the plug so the motor stops running and doesn't flood or burn oil or what ever. If those sensors go bad it could miss read that it's upside down or not work at all ..

I don't believe motocross bikes are equipped as such, though I don't know for sure. I do know that my bike rarely remains perpendicular to the ground, both on the ground and in the air. 

I don't believe motocross bikes are equipped as such, though I don't know for sure. I do know that my bike rarely remains perpendicular to the ground, both on the ground and in the air.

I don't they have them either but I wa just explaining what the sensor does and how I think it would fail

I don't believe motocross bikes are equipped as such, though I don't know for sure. I do know that my bike rarely remains perpendicular to the ground, both on the ground and in the air.

I know KTMs have one...

The YZ does have a tip-over sensor built into the ECU.  They usually allow the engine to remain running for 20 seconds or so once they are down.  Haven't heard of one failing in any way, but I have heard of people mounting headlights and crap relocating the ECU incorrectly and the bike not running because of it.

Interested to hear the culprit on this one as I care not to have this happen on my '14.

So I had the same issue with my 09 crf 450 and it was the fuel filter in the tank I replaced it and it hasn't bogged since. idk if this is any help but it would only bog on the face of jumps or under a hArd load

MXA says the bike is very lean with the stock map and "feels like it wants to cut out on some landings" or something to that effect. I haven't experienced it but some things that come to mind are: 

 

1. which map are you running?

2. Idle speed too low?

3. How much fuel did you really have? Is it possible that with the above factors and a very low fuel level, a long zero G flight and nose down attitude could cause a flameout?

This is the map I'm running, borrowed from a thread on here a while back...

 

FI: 333     IG: 222
     343           232
     233           222
 
 
I have always tried to keep my idle speed nominal. I don't like it too high, but don't want it to die either. I will definitely make a conscious check of it.
 
 
The tank was definitely full. I had just topped it off and checked it again after evaluating the carnage. 
 

The way you describe it though seems spot on. It was like it just ran out of fuel, and being over a large jump with seemingly less downward force, I suppose that could happen. But it seems odd to be sure. I'm scared to ride the stupid thing and that pisses me off.

 
Edited by swaldrop

Glad to hear you're OK.  My 2011 never cut out, but my '12 did bog once over a minor jump - landed on top instead of on the downside.  No crash, but it did shake me a little to wonder if it will happen again.  I haven't been able to replicate it, but suspect it was a slightly lean condition.  Another thought - does the '14 have a fuel check valve?  If so, that might be clogged.  I've never trusted those, anyway.

Issues like this have come up in the past, and so far, they have been traced back to the fuel pump one way or other.   So far, the problems have been caused more by dirt in the fuel than any other single factor.  The fuel filters in the EFI systems are MUCH finer than the filters used with carburetors (KTM uses a 10 micron filter), and it doesn't take a lot to close them down, so that would be one place to look. 

 

Clean your gas cans. ;)

Go to your local hardware store and buy a large pack of paper paint filters. It's a PITA but an easy way to catch debris out of the dirty pump fuel.

Dam I remember you telling me your bike cut out last week at bartow but I was unaware you crashed. This is Keith you know the one with the new white 13 yz450f...anyhow dont rule out water in fuel. A small amount of water will stay seperated and kill the motor at will. I would dump full first into clear container and inspect before I go ripping into the bike.

I haven't done much yet but replace the bars and clutch lever. I am hesitant to start tearing it apart without having a clear direction. I will probably drain the fuel and inspect the fuel pump for debris. I may even bypass the kill switch. Other than that, I am not real sure what to do.

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