Alta Redshift MXR and MX on a Dyno - Riding Maps Demystified

[snydes]

@Fog 25 is having pretty good results with map 4 and a gearing change as far as battery life.

 

[Fod]

My last ride I didn't have time to charge the battery fully but wanted to get some laps in and so I rode map1 the whole time and it was actually super fun trying to keep my momentum! And the battery depletion was impressive for the pace I was at. (I did hit map 2 for a moment to get by another rider...I tried in map 1 but was getting pelted too much and couldn't make it stick). By the way screaming at riders on some bikes doesn't work 100% of the time and I have gotten in some pretty close calls making passes. Has anyone gone down in a collision due to the other rider cutting in or pushing wide on you?!?!

 

[snydes]

Have to mount an air horn on the bars....

 

[Philip]

Well... I was too impatient to wait for the dyno data, so I digitized the MXR Dyno pictures. I wanted to see what a 14-tooth front sprocket would do to these curves.

Here you go:

____ Power MXR Map 4
____ Power MXR Map 3
____ Power MXR Map 2
____ Power MXR Map 1

- - - Power MXR Map 4 with a 14-tooth front sprocket
- - - Power MXR Map 3 with a 14-tooth front sprocket
- - - Power MXR Map 2 with a 14-tooth front sprocket
- - - Power MXR Map 1 with a 14-tooth front sprocket

 

[Philip]

____ Torque MXR Map 4
____ Torque MXR Map 3
____ Torque MXR Map 2
____ Torque MXR Map 1

- - - Torque MXR Map 4 with a 14-tooth front sprocket
- - - Torque MXR Map 3 with a 14-tooth front sprocket
- - - Torque MXR Map 2 with a 14-tooth front sprocket
- - - Torque MXR Map 1 with a 14-tooth front sprocket

 

[Philip]

In motocross, at my local tracks, I never exceed 45mph.

So...with a 14-tooth front sprocket...

In Map 4, I would get the acceleration of the stock Map 3 at low speeds and the acceleration of the stock Map 4 at high speeds.

In Map 3, I would get the acceleration of the stock Map 2 at low speeds and the acceleration of the stock Map 2/3 at high speeds, plus about 5% extra.

Overall, you get more usable power with a 14-tooth front sprocket!

 

[Kurlon]

I think the estimates are slightly off, the HP should be reduced across the board as a result of the taller gearing. Remember we're looking at rear wheel HP, not estimated crank / countershaft HP.

 

[Philip]

Only torque (at the rear wheel, to be technically correct) changes with different gearing.

The HP does not change with gearing. Power = Torque * Speed. The torque goes down, the speed goes up, the HP stays the same. What changes is the speed where that max HP occurs.

 

[Philip]

I found some 2018 250cc dyno data. It bothers me that different dynos report such different numbers! And two of these dynos are DynoJets.

Dirt Bike Magazine 2018 250cc on the dyno:
https://dirtbikemagazine.com/friday-wrap-up-250-mx-bikes-on-the-dyno


Dirt Rider Magazine 2018 250cc on the dyno:
https://www.dirtrider.com/2018-250f-mx-shootout#page-3


Vital MX 2018 250cc on the dyno:
https://www.vitalmx.com/features/2018-Vital-MX-250-Shootout,5636

 

[snydes]

My last ride I didn't have time to charge the battery fully but wanted to get some laps in and so I rode map1 the whole time and it was actually super fun trying to keep my momentum! And the battery depletion was impressive for the pace I was at. (I did hit map 2 for a moment to get by another rider...I tried in map 1 but was getting pelted too much and couldn't make it stick). By the way screaming at riders on some bikes doesn't work 100% of the time and I have gotten in some pretty close calls making passes. Has anyone gone down in a collision due to the other rider cutting in or pushing wide on you?!?!

Found you a horn....

 

[Fod]

Found you a horn....View attachment 405

Ha ha, I need the center button on my map switch to toggle it! And I can use it when I get passed also to scare the rider off the track!

 

[snydes]

Maybe you could also strap a small chainsaw engine minus the bar and chain to the handlebars. That would probably win over the Ronnie Mac fans too.

 

[Fod]

Maybe you could also strap a small chainsaw engine minus the bar and chain to the handlebars. That would probably win over the Ronnie Mac fans too.

And it can charge up the battery! Hybrid safety!

 

[Mark911]

There are so many variables when it come to dynos and their operators it's almost impossible to get absolute numbers. At best, only a relative qualitative comparison is valid. The gear, the gear ratios, the load, the rear tire size and type, fuel, the dyno calibrations and compensations (many of which can be manipulated) are just a few and don't even consider difference between dynos and dyno types. Still interesting to see the relative differences between MX/MXR maps.

 

[Philip]

I am inclined to believe the dyno that I used. It reported HP numbers that are close to the advertised ones.

Wish I still had my Husky TC250 and a Yamaha YZ450F. Those would have been interesting add-ons to this data. But regardless, both the measured and the advertised numbers seem accurate, and they explain why the Alta bikes blow by the competition so easily. It would have to be a Glen Helen type of a track for a 450cc bike to beat the MXR, assuming the riders are of the same skill level.

 

[Philip]

I have added a 14/45 sprocket combination. It is initially similar to running in the stock Map 2, only with way more power above 28mph. Whole 15hp more at 45mph! Not a bad combination at all.

____ Power MXR Map 4 with stock 12/53 sprockets
____ Power MXR Map 3 with stock 12/53 sprockets
____ Power MXR Map 2 with stock 12/53 sprockets
____ Power MXR Map 1 with stock 12/53 sprockets

- - - Power MXR Map 4 with 14/53 sprockets
- - - Power MXR Map 3 with 14/53 sprockets
- - - Power MXR Map 2 with 14/53 sprockets
- - - Power MXR Map 1 with 14/53 sprockets

. . . . Power MXR Map 4 with 14/45 sprockets
. . . . Power MXR Map 3 with 14/45 sprockets
. . . . Power MXR Map 2 with 14/45 sprockets
. . . . Power MXR Map 1 with 14/45 sprockets


____ Torque MXR Map 4 with stock 12/53 sprockets
____ Torque MXR Map 3 with stock 12/53 sprockets
____ Torque MXR Map 2 with stock 12/53 sprockets]
____ Torque MXR Map 1 with stock 12/53 sprockets

- - - Torque MXR Map 4 with 14/53 sprockets
- - - Torque MXR Map 3 with 14/53 sprockets
- - - Torque MXR Map 2 with 14/53 sprockets
- - - Torque MXR Map 1 with 14/53 sprockets

. . . . Torque MXR Map 4 with 14/45 sprockets
. . . . Torque MXR Map 3 with 14/45 sprockets
. . . . Torque MXR Map 2 with 14/45 sprockets
. . . . Torque MXR Map 1 with 14/45 sprockets

 

[Fod]

Cool! Hp map 1-3?

 

[Philip]

Fixed!

 

[MattB]

Very cool! Not that I would ever get above 45mph on the track but I find it interesting that the power stays higher after 45mph!

 

[ElectroBraap]

Question. How is torque at the motor measured on the dyno? I'm imagining you would just measure it at the wheel and devide it by the gear reduction ratio?..Then we have the sprokets sizes to factor in as well? Forgive me if these are not the correct terms.

-Electro