The Honda PCX / Forza / ADV150 / SH Forums

I bought this Honda PCX Variator which was custom made by Mad Max Bangkok Shop. I get a very stable upper end top speed of 110km/h.

https://www.facebook.com/photo.php?fbid ... =1&theater

thats it? i do 109km/h with stock variator. all they probably did was do a little shaving to the slider ramps and are selling it. You can do the same for 20min of time.

alvinsgp wrote:I bought this Honda PCX Variator which was custom made by Mad Max Bangkok Shop. I get a very stable upper end top speed of 110km/h.

JDMChris wrote:thats it? i do 109km/h with stock variator.

One has to specify whether that is true speed or speedometer reading, otherwise the numbers are meaningless.

My PCX150 is stock and hits rev limit at 113km/hour (GPS).
But if not a steep enough downhill, it may look like top speed is somewhat less because there is not enough power to reach the rev limit.

I think for the sake of testing variators for top speed, I would test it on the stand (if I can reduce the vibration it currently has).
This would allow one to quickly and reliably assess any changes in rev-limited top speed.

alvinsgp wrote:I bought this Honda PCX Variator which was custom made by Mad Max Bangkok Shop. I get a very stable upper end top speed of 110km/h.

https://www.facebook.com/photo.php?fbid ... =1&theater

Does not look any different to a stock one?

wingz wrote: I think for the sake of testing variators for top speed, I would test it on the stand (if I can reduce the vibration it currently has).

Testing on the stand doesn't show much as there is no real-world wind resistance. Top speed at 13.5 hp is about 120 from TS=Cx(HP^1/3) Using 31.5 as the constant ( taken from previous 125 results)
This off course assumes that the engine doesn't run out of revs.

waspmike wrote:

wingz wrote: I think for the sake of testing variators for top speed, I would test it on the stand (if I can reduce the vibration it currently has).

Testing on the stand doesn't show much as there is no real-world wind resistance. Top speed at 13.5 hp is about 120 from TS=Cx(HP^1/3) Using 31.5 as the constant ( taken from previous 125 results)
This off course assumes that the engine doesn't run out of revs.

I disagree that testing on the stand doesn't show much. you can glean a lot of information by testing on the stand.
Thanks for that formula. I would like to use it. Please can you explain how you get 120 using that formula?

Please explain what you learn on the stand? It is not the real world.

Formula is what it is, use it 13.5hp and 31.5 Constant and you will get 120 kph. Most calculators have a power function if not use excel.

The constants are different for different bikes or types of bike but it works for Hyabusa road test etc.. just different constant, which can then be verified with a Honda Blackbird test.

The problem with PCX is there is little info on real top speed that isn't somehow muddled with speed or rev limit.
SYM 300 has a slightly lower constant which means it is less aerodynamic.

I am still looking for a formula about slope and what it adds so I can incorporate information about speed going downhill to my numbers.

Gravity is 9.81m/s^2.
If you have a 1/10 slope then the additional acceleration contributed by gravity is (1/10)*9.81 [m/s^2].

Regarding your formula, I got confused when I didn't get 120... then realised that it gives answer in mph.
Thanks, it is a nice formula.

What you learn on the stand is what difference the variator makes.
You first do the test WOT, record with camera speedometer and rpms. Plot a graph of rpm vs speed.
Then you can run WOT but use the rear brake to hold the speed constant at various speeds of interest, eg 60, 80 and 100km/h and not the rpm at each speed.
May/may not be any different from the plotted graph but at least it can be measured and confirmed.

The above procedure gives you a baseline. It is not supposed to simulate real world riding.
When you install a new variator, you run the same test.
This allows you to see what difference the variator makes.

The trouble with real riding is that you have variable conditions (wind, slope etc) which interfere with your measurements.
The key for any comparison is consistency.

Sounds like the engineers forum

I will incorporate this in my testing also Wingz. Ty for bringing up your point.

I did realize that one thing one gets is potential top speed at the rev limit as opposed to top speed limited by something other than revs, like a HP limiter.
I suppose also that applying more rear brake would show the action of the counter spring and simulate uphill riding and down shifting.

Most videos show the speedo to prove more speed, but we usually cannot tell if the road has a slight downhill slope or which way the wind is blowing.

Somewhere I have a photo of a Honda Wave speedo at 140 kph. It is broken and vibration has moved it to 140.

But I am still not wholly convinced that on the stand converts to the real world. Maybe a poor man's dyno

Yes , apologies my spread sheet shows kph because I converted. It is a revelation to see how much little speed HP increase yields.

What I now need to do is see how the down hill slope can be converted to HP. As that would aid the process of determining the HP at what speed.

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logepoge

May not be an engineer's forum but it helps to understand stuff before adding performance bits.

I would have no problem with it being an engineers forum since I am an engineering student. It's fun stuff, not boring, and fun to learn how stuff works

Two disclaimers regarding testing on the stand:

1. It might not be a good idea due to vibration. Be careful not to break something.
2. It is not intended to accurately simulate real world conditions. I believe it is more helpful though, because it gives one more control over the test conditions.

waspmike wrote: What I now need to do is see how the down hill slope can be converted to HP. As that would aid the process of determining the HP at what speed.

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logepoge

May not be an engineer's forum but it helps to understand stuff before adding performance bits.

Force = Mass x Acceleration where acceleration = 9.81 x slope factor.
Power = Force x Velocity.