C 400 GT: Top Speed in Agreement With Owner's Manual

wspollack

Active member
In case anyone was wondering ...

The owner's manual for my 2022 C 400 GT lists (on page 197) a top speed of 86 MPH. I recently received footage of that scoot, with post-break-in mileage on it, confirming that figure. The anonymous rider noted that the throttle was held WFO, and that the display's readout during max speed was a steady, if slightly higher, 88 MPH:


(Telemetry was courtesy of a GoPro Hero9 Black, which has a commendable sampling rate of 18 Hz.)
 

byee

Active member
I have had my 2019 C400GT up just past 140kph but the RPM’s was not screaming. Probably can still go faster.
 

wspollack

Active member
I have had my 2019 C400GT up just past 140kph but the RPM’s was not screaming. Probably can still go faster.
Some comments on your comment:

1) To reiterate and amplify, the speedo had a rock-solid, unwavering, reading of 88 MPH for those three or four seconds in the video.

I was recording using the GPS capability of my GoPro Hero9 Black. This is a good GPS, as it has a sampling rate of 18 Hz, which is very high (most phones, for instance, only check in with satellites at 1 Hz). So I trust that much more than the bike's speedo, or phone apps that check speed.

2) The 88 MPH reading is, therefore c. 2.3% higher than (the GoPro's) reality. That figure is, in my experience noting such things over the years, actually quite low, i.e., reasonably accurate. On both of my Burgman 650s (an '07 and an '08), I added a Speedo Healer, and set both of those to -9.2% (with new, full-siping-depth, tires, and using a couple of Garmin devices and a phone app), which is on the other extreme.

All of those discrepancies are legal, of course. There are complicated rules in place in Europe and the US regarding allowable discrepancies, based on the type of vehicle and some other factors (I researched this a long time ago), but certainly 10% over is acceptable.

Am I correct that your 140 KPH (87 MPH) reading was based on looking at the speedometer, not based on some GPS or other timing device?

3) I'm in agreement with you that the revs didn't seem to max out.

Given that, and given the rock-solid nature of the speedo display when I was doing that test run, and given that it was downhill, I'm beginning to think that the top speed -- the 86 MPH -- listed in the owner's manual is governed somehow by the bike's electronics. That is, I think it could go a bit faster, if not for such interference.

4) One of these days, I'll make another video test. But this time I'll mount the GoPro such that it's looking at the bike's speedo AND a phone-based speedo app while its recording. And maybe find a longer downhill stretch. Then we'll both be able to see this in action, preserved in video.

5) BTW, I've done a few experiments of 200+ miles each during and after my post-breakin period, and found the bike's odometer to be within a tenth of a percent or so, i.e., basically dead-nuts on, as the expression goes.
 
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wspollack

Active member
Update, Four Months Later:

Near the tail end of a day trip today -- during which the odometer rolled past the 4,000-mile mark -- I decided to do another test. The intervening miles seem to have done the engine no harm, as I squeaked out an actual speed of 89 MPH (143 KPH, for those who make better use of the decimal system):


Incidentally, the TFT was displaying 92 for those split-seconds that the actual speed got up to 89, or about a 3% high reading (vs. the about 2% high reading in my first post above -- I suspect the difference is somewhere between the two), which isn't bad (both of my 650 Burgman Execs read about 9.2% high).
 

byee

Active member
I’ve gotten my C400GT up at 141kph. Never thought of pushing it all the way nor did I realize I was a couple kph away for the top speed.

I had no issues getting it up there either.
 

janpoko

New member
…..thinking the GT designation should give us at least + 5kph than your C400X

😀
I will try the top speed next week also with a video. Nevertheless I hate to put the scooter to its limits, so I am trying not to ride above its paper maximum often. :)
 

wspollack

Active member
@byee, @janpoko, et al.:

First of all, let's make sure we're on the same page, comparing apples to apples, and other such expressions.

That is to say, the top speeds I listed in this thread -- 86 MPH (138 KPH), after about 1,000 miles on the scoot, and 89 MPH (143 KPH), after about 4,000 miles -- were the speeds as determined by a GPS (in my case, an 18 Hz GPS chip on the GoPro Hero9, and a 10 Hz Hero11 chip). These were NOT the speeds listed on the bike's display; those approximate speeds (i.e., 2% - 3% higher than reality, per my observations) were, respectively, 88 MPH (142 KPH) and 92 MPH (148 KPH).

(To recap: the 86/138 figure is what's listed in my owner's manual as the top speed, and after the break-in period I thought I confirmed that. However, with additional mileage, I have now confirmed 89/143. And by "confirm," I mean using a GPS.)

So, are the speeds you folks are posting about GPS-determined speeds, or speedometer-listed speeds? If the latter, they're perhaps indicative of relative speeds, but not real speeds.

Next, I, too, had no problem getting up to those speeds, as you can see in my videos ... especially the last one (post #4), when I was on level ground, and just gave it some more throttle. Only took a few seconds to top out.

I hadn't really planned on this second test, but I noticed I was going pretty fast, had recently passed a LEO on the side of the road who was giving someone a ticket, and so just decided to wick it up. I still have to do a planned test again, with a second camera recording the display, and with the display set on Urban, to show both the speedometer and engine RPM display. I'm not sure I can get this in before the season ends for me, but I'll see what I can do.

(By the way, it bugs me that the RPMs are only displayed on the Urban setting. I usually run with the My Vehicle display, which has room for a tach readout. And which certainly doesn't need to display a picture of the scoot -- I know what it looks like. If some programmer is really proud of that bike picture, it could be displayed for a few seconds on start-up, and then disappear. But I digress.)

Last, I wouldn't worry at all about keeping the bike at top speed for an extended period of time. A friend of mine -- he and his wife were with my wife and me, when we did the Edelweiss "Tuscany by Scooter" tour this past May -- did an IBA "Saddlesore 1000" on his C 400 GT a few months ago: see www.youtube.com/watch?v=mqo-P_uSO50, if you're interested in a quick overview he put up.

That's 1,000 miles in less than 24 hours (in his particular case, it was about 20 hours). He wrote to me afterwards, "I am convinced you can ride this thing W.O.T. all day long." As I say, I wouldn't worry about running a little faster than some of us run much of the time on highways. It certainly would be informative to see what the RPMs are at top speed, though.
 
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byee

Active member
It’s common knowledge the speedos are incorrect. I have used apps such as speedometer to check speeds. It’s GPS driven but don’t know what the error margin is
 

janpoko

New member
@byee, @janpoko, et al.:

First of all, let's make sure we're on the same page, comparing apples to apples, and other such expressions.

That is to say, the top speeds I listed in this thread -- 86 MPH (138 KPH), after about 1,000 miles on the scoot, and 89 MPH (143 KPH), after about 4,000 miles -- were the speeds as determined by a GPS (in my case, an 18 Hz GPS chip on the GoPro Hero9, and a 10 Hz Hero11 chip). These were NOT the speeds listed on the bike's display; those approximate speeds (i.e., 2% - 3% higher than reality, per my observations) were, respectively, 88 MPH (142 KPH) and 92 MPH (148 KPH).

(To recap: the 86/138 figure is what's listed in my owner's manual as the top speed, and after the break-in period I thought I confirmed that. However, with additional mileage, I have now confirmed 89/143. And by "confirm," I mean using a GPS.)

So, are the speeds you folks are posting about GPS-determined speeds, or speedometer-listed speeds? If the latter, they're perhaps indicative of relative speeds, but not real speeds.

Next, I, too, had no problem getting up to those speeds, as you can see in my videos ... especially the last one (post #4), when I was on level ground, and just gave it some more throttle. Only took a few seconds to top out.

I hadn't really planned on this second test, but I noticed I was going pretty fast, had recently passed a LEO on the side of the road who was giving someone a ticket, and so just decided to wick it up. I still have to do a planned test again, with a second camera recording the display, and with the display set on Urban, to show both the speedometer and engine RPM display. I'm not sure I can get this in before the season ends for me, but I'll see what I can do.

(By the way, it bugs me that the RPMs are only displayed on the Urban setting. I usually run with the My Vehicle display, which has room for a tach readout. And which certainly doesn't need to display a picture of the scoot -- I know what it looks like. If some programmer is really proud of that bike picture, it could be displayed for a few seconds on start-up, and then disappear. But I digress.)

Last, I wouldn't worry at all about keeping the bike at top speed for an extended period of time. A friend of mine -- he and his wife were with my wife and me, when we did the Edelweiss "Tuscany by Scooter" tour this past May -- did an IBA "Saddlesore 1000" on his C 400 GT a few months ago: see www.youtube.com/watch?v=mqo-P_uSO50, if you're interested in a quick overview he put up.

That's 1,000 miles in less than 24 hours (in his particular case, it was about 20 hours). He wrote to me afterwards, "I am convinced you can ride this thing W.O.T. all day long." As I say, I wouldn't worry about running a little faster than some of us run much of the time on highways. It certainly would be informative to see what the RPMs are at top speed, though.
Ok, sorry. I havent noticed that you used GPS to measure. The real speed is of course a bit slower. Anyway, I will try the GPS to see the difference.
 

wspollack

Active member
LONG DOWNHILL RUN, TACH INCLUDED:

Okay, I went for a ride yesterday, which I'm pretty sure now was the end of the season for me. I aimed a camera at the TFT for awhile, with the Urban (i.e., tach) display on. The center of this pic is the area in the video, a long downhill stretch of a state road (west to east, in my case):

Screen Shot 2022-11-08 at 8.20.48 AM.jpg

And here's the video (two minutes), showing two WOT chunks, the second (faster) of which shows:

- A max displayed speed of 94 mph (151 kph).
- A max GPS speed of 91.6 mph (147 kph).
- A max RPM display of 8800.

This was during a drop of about 630 feet (c. 190 meters), over the course of about 2.6 miles (4.2 km). Here's the video:


I'm done with this C 400 top-speed experiment, unless I can do it on the autobahn sometime. Oh, and of course your speed may vary. I forgot to note anywhere in this thread that I have Wonderlich's "Marathon" windscreen, which is bigger than the stocker, and my guess has more wind resistance. And I'm no featherweight, either, coming in at about 94 kg (plus gear).
 

mzflorida

Active member
It’s common knowledge the speedos are incorrect. I have used apps such as speedometer to check speeds. It’s GPS driven but don’t know what the error margin is
Rviving an old post. On my 23 GT, the speedo seems optimistic up to about 45 actual MPH, then starts to align somewhat accurately, then becomes a pessimistic above that where your actual speed is slightly higher than the speedo. It's early for me, but that is my impression thus far.
 
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