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2012 NTX sudden loss of performance, burning plastic smell

defied

Tuned and Synch'ed
Joined
Sep 11, 2017
Messages
41
Location
Tacoma, WA
Hi all,

So for background, I have the 2012 and last fall had a shop replace the cam assemblies (that defect we all know about).

Anyways, I brought it home, and kept it stored over the winter and spring (occasionally warming it up to keep it lubricated and healthy).

So I finally pulled the bike out for the summer about two weeks ago, and have ridden it probably 5 or 7 times a few miles here and there (maybe put about 60 miles on it tops).

Riding home today, I heard something spinning (like a 'ZZzzzzzzzzzzzzzzzzz!!!!!' noise), and immediately lost horsepower. I got control of my bike and brought it to the side of the highway, hazards on. I took a look around and didn't see anything out of order, so I limped the bike the last mile home and parked it.

When I hopped off again, I still smelled burning plastic, and I can't see anything that would make me nervous (which makes me even more nervous thinking it's in the engine).

The motor sounded completely different. It wasn't the clap clap when the cams were going bad, and it wasn't the usual rumble. I'd almost say it was louder and deeper, and more staggered.

Has anyone experienced this, or have an idea of what could have happened?

Thanks in advance,
D
 
Isn't this one of the bikes that had some troubles with spark plug boots? Could one of your spark plug boots be grounding out and making it run only on one cylinder?
 
That would be the 1st thing I'd look at and I have seen the wires unplug from coil. There is a thread here on replacing the caps with NGK hard caps. Look it up for good info.
 
I was actually thinking the same thing when I was out for dinner. That's what I'm going to check today. Thanks!

D
 
I remember doing the NGK mod a few years back, I tested arc and they appear to work just fine.

That said, it def looks like a cylinder timing or mis-firing issue.
When I leave the left spark detached and fire up the engine, it's that same deep throttle I described earlier.
When I plug it back in, I still get that deep throttle, but every once in a while there's a pop.

What do you guys think? Bad sparkplug? Fuel filter? Anything besides that (remembering this bike has only 60-ish miles on it since they replaced the upper end of both cylinders?
 
If only one side, not the fuel filter. Only items that work on that side. Coil, spark plug, spark wire, or injector. With the burnt plastic smell, I'm thinking a coil may have cooked.
 
If only one side, not the fuel filter. Only items that work on that side. Coil, spark plug, spark wire, or injector. With the burnt plastic smell, I'm thinking a coil may have cooked.
Thanks! I'm hauling it to my buddy's shop this week. I'll take a look then.
 
If only one side, not the fuel filter. Only items that work on that side. Coil, spark plug, spark wire, or injector. With the burnt plastic smell, I'm thinking a coil may have cooked.
As I'm thinking about it, if the coil was shot I shouldn't be getting an arc down to the plug, should I?
 
May not be enough voltage to fire the spark plug under compression.
It got me pretty good when I got too close. Lol!

Yeah, I've got an appointment to take it in and have the guys who did the tappit mod to take a look at. If it's not from their work, then we should be able to find out what's wrong.

At that point, I may fix it and sell it. It almost threw me over the bars on a major highway. I have trust issues at the moment.

D
 
Might be worth checking the Alternator Belt.
If that failed, you'd probably get a burning smell, either from the Belt itself slipping, or from it flailing around against the Plastic Front Cover.
The loss of power is puzzling though, if it is anything to do with the Belt.

I've had a misfire before that cut both Cylinders momentarily, the effect was no worse than shutting the Throttle fully at speed.

Could an Electrical fault cause the Starter Motor to engage?
That would probably feel like slamming the Brakes on . . .
 
Might be worth checking the Alternator Belt.
If that failed, you'd probably get a burning smell, either from the Belt itself slipping, or from it flailing around against the Plastic Front Cover.
The loss of power is puzzling though, if it is anything to do with the Belt.

I've had a misfire before that cut both Cylinders momentarily, the effect was no worse than shutting the Throttle fully at speed.

Could an Electrical fault cause the Starter Motor to engage?
That would probably feel like slamming the Brakes on . . .

I think it was more the engine spinning down from such a high speed after it shut off. It didn't feel like hard braking, more no engine power, doing speed down the highway in gear.

Interesting thought about it being the belt.
 
Was just trying to think of something spinning under/behind a Plastic Cover.
Again, it's the sudden loss of Power that's puzzling.

The comment "It almost threw me over the bars on a major highway" made me think it was more 'violent' than just closing the Throttle (or flicking the Kill Switch) would feel.

I'd lean towards something that would have been disturbed during the Roller Kit fitting.
Did it feel like it was running on one Cylinder, or was it totally 'dead'?
 
So, the shop came back and said it was the lambda sensor. They recommend replacing both. Parts and labor look to be around $700.

I think the "zzzzzz' noise was because the engine was in gear and powering down.
My understanding of lambda sensors and the fuel injection control *could* see this as making sense. What do you guys think? Could it be a that?

D
 
Parts and labor look to be around $700.

You need to RUN, not WALK away from that shop! They are trying to rip you off.

The longer sensor (660 mm), part # 896110, Moto Guzzi List Price is $119.70 and the shorter (325mm), Part # 584344, Moto Guzzi List Price is $115.30

That totals $235. It does not take $465 labor to install 2 λ sensors. Takes about 15 minutes each.


Buy them from Todd here on the site in the STORE section. You can install them yourself as they are EASY and save yourself $$$$.
 
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I would not believe that it is the Λ sensors unless there is a code thrown in dashboard OBD.

Lambda Probe Error ECU 21

It's in the Service Manual in the Downloads section.

Screen Shot 2021 07 15 at 51030 PM
 
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