Varying redline ...?

[Grumpy Goat]

Went for a ride yesterday when the ambient temperature was a cool 55 deg.F or so. After the bike warmed up the tachometer showed the redline as being the usual 9000 rpm.

However as I continued the 130 mile non-stop ride I happened to notice at some point the indicated redline had dropped to 8000 rpm. That was weird, I thought. Engine was warmed up so what was with the lower redline?

I checked ambient temperature (57 or so deg.F) and then the engine temperature (169 - 171 deg,F) and figured that maybe because the engine was running cool the redline was decreased ...? After all when you first start the bike for the day the engine is not warmed up and the redline is like 4000 rpm until the normal operating temperature is reached. I was riding between 65 and 75 mph, so it was not like I was riding slowly. I did not ride the bike to the indicated redline to see whether it would cut power at 8000 rpm.

Anyone else notice this? Just curious. I am not bothered about this on my bike.

From what I read, redline is the maximum continuous rating below which the engine and its components are designed to operate without suffering damage to itself or other parts directly connected to it. So it would depend on primary factors such as stroke / displacement, mass of components, material composition of components, mechanical arrangement, etc. Makes sense to me.

BMW Motorrad limits the redline of our engines electronically to force operation to be in a lower safe zone while the engine is being warmed up. During that time the oil is not distributed throughout the engine as designed, and the engine tolerances are not yet expanded to their design values. Makes sense to do that.

So that leaves me to wonder ... is the electronic nanny so picky that, even after warming up, it would still vary the redline depending on the cooler ambient temperature? The redline did eventually go back to 9000 rpm, but then it also dropped back to 8000 rpm at least at one point before the end of the ride.

[Lee]

I have no idea as I rarely look at the bar scale tach on my bike.
When I check the tack I look at the digital readout.
I didn't realize the rev limiter would kick in early when the tach is showing a lower redline.

[BobAin'tStoppin']

I wonder if you have a sensor issue. You are correct, or course, about red line and proper warm up. The issue is more oil temp rather than water temp. I don't know what the bike looks at to make it's decision. I have never noticed this on my bike, but really don't pay attention to the indicated red line.

[Grumpy Goat]

I wonder if you have a sensor issue. You are correct, or course, about red line and proper warm up. The issue is more oil temp rather than water temp. I don't know what the bike looks at to make it's decision. I have never noticed this on my bike, but really don't pay attention to the indicated red line.

Bob you might be right, and like you I don't know what it is looking at. Today I went out ("Christmas shopping" ) and it was a little warmer (by the end of the ride about these suburbs) and I was riding much slower - 45 - 50 mph max. The redline showed both 9000 rpm when the engine had reached temp but it was like 55 deg.F and I was driving at the speed mentioned above. And then it also showed 8000 rpm when driving the same speed and the ambient temp was slightly higher. So who knows ...

Weird, that's all.

[Grumpy Goat]

I wonder if you have a sensor issue. You are correct, or course, about red line and proper warm up. The issue is more oil temp rather than water temp. I don't know what the bike looks at to make it's decision. I have never noticed this on my bike, but really don't pay attention to the indicated red line.

Bob you might be right, and like you I don't know what it is looking at. I also don't bother with the redline either ... just that I happened to notice this yesterday and wondered why I lost 1000 rpm of power range ... I was riding more aggressively yesterday.

Today I went out ("Christmas shopping" ) and it was a little warmer (by the end of the ride about these suburbs) and I was riding much slower - 45 - 50 mph max. The redline showed both 9000 rpm when the engine had reached temp but it was like 55 deg.F and I was driving at the speed mentioned above. And then it also showed 8000 rpm when driving the same speed and the ambient temp was slightly higher. So who knows ...

Weird, that's all.

[mspratz]

It would be interesting to switch the display to Engine Temperature next time you see the redline drop like that. I've ridden plenty of times in temps just above freezing, and I don't recall ever seeing the redline drop once the bike is warmed up. Generally the engine temp seems to be around 170-180 F on a cold day.
I'd be wondering if, as suggested earlier, it might be a failing temperature sensor, or alternatively a failing thermostat. The thermostat might be opening prematurely and keeping the engine temp below the ideal range on cool days.

[Lee]

Is it normal for the redline to display 4000, then 8000 as the oil warms then 9000 when the oil reaches safe operating temp. ?
I figured it went from 4,000 to 9,000.
Seems odd to have the redline jump from 4,000 to 8,000, then have a small jump to 9,000.
Like I mentioned before I rarely look at the tach bar scale.

[Grumpy Goat]

Is it normal for the redline to display 4000, then 8000 as the oil warms then 9000 when the oil reaches safe operating temp. ?
I figured it went from 4,000 to 9,000.
Seems odd to have the redline jump from 4,000 to 8,000, then have a small jump to 9,000.
Like I mentioned before I rarely look at the tach bar scale.

Oh, mine does not jump from 4000 to 8000 ... it just starts at about 4000 and gradually progresses up to 9000 rpm.

This behaviour I am describing is after it has warmed up to the normal 9000 rpm limit, it periodically drops down to 8000 rpm, and then may also jump back up to 9000 rpm. All while the engine and ambient conditions are more or less constant.

Like Mike and Bob have suggested, I am suspecting a sensor acting up.

[Grumpy Goat]

I'd be wondering if, as suggested earlier, it might be a failing temperature sensor, or alternatively a failing thermostat. The thermostat might be opening prematurely and keeping the engine temp below the ideal range on cool days.

I guess the thermostat could also contribute to this problem although the engine temp seems to be at the lower end of the range you mentioned. I expect to be going out tomorrow again, to review a Cool Covers seat cover, and maybe finish off my Christmas shopping ... , so I will also be keeping an eye on the engine temp on my replacement Nav VI.

[Lee]

This behaviour I am describing is after it has warmed up to the normal 9000 rpm limit, it periodically drops down to 8000 rpm, and then may also jump back up to 9000 rpm. All while the engine and ambient conditions are more or less constant.

Yep, I understood your original post, I was just asking what was normal behavior.
The gradual redline change you describe make sense.

[Ray]

However as I continued the 130 mile non-stop ride I happened to notice at some point the indicated redline had dropped to 8000 rpm. That was weird, I thought. ...

Anyone else notice this?...

Nope.

[Olgry1]

Not sure if the GS911 will tell you anything but you may want to hook one up and see what it shows.

[Ray]

...This behaviour I am describing is after it has warmed up to the normal 9000 rpm limit, it periodically drops down to 8000 rpm, and then may also jump back up to 9000 rpm. All while the engine and ambient conditions are more or less constant.

Like Mike and Bob have suggested, I am suspecting a sensor acting up.

I'm going to guess that this is related to your NAV VI issues.... ()

Olgry's thought seems good, as usual.

[Grumpy Goat]

Yep, I understood your original post, I was just asking what was normal behavior.
The gradual redline change you describe make sense.

Oh, OK. Yes it starts at 4000 rpm and then increases gradually to 9000 rpm. I went for another ride today but totally neglected to look at the tach. Today was the warmest day of the week so far.

[Grumpy Goat]

Not sure if the GS911 will tell you anything but you may want to hook one up and see what it shows.

Yes, I thought about that ... great idea. Will do that maybe tomorrow, and report back.

[Grumpy Goat]

I'm going to guess that this is related to your NAV VI issues.... ()

Hahaha ...

Imagine if this bike was made by Garmin! The horror!!