Honda PCX125/Vario125 cheap EFFECTIVE mods

[clemence]

I just want to share some cheap effective mod here:
With standard spec the bike can only pull 118km/h static, 105km/h flat road, and 115+km/h down hill. I use this scooter everyday and found it to be too slow especially when I had to drive in highway (Bali highway). Because normal cruising speed in highway is around 80-90km/h without passing other vehicles.
Then I mod the variator using rotary burr and (mainly) small files and lots of sandpapers (the shape just didn't allowed my burr tips to do it properly) so that the roller can move out further and the pulley outer "dead space" can be used by the belt. And milling the center of the inner variator width by 0,5mm so that they don't butt together before the roller max out the travel. With this mod only the top speed didn't changed much because the engine still doesn't have enough power to reach the required RPM. The result was 130km/h static, 107km/h flat road, and 122km/h down hill
But you have the capacity to move faster down hill.

I then experimented with valve lash adjustment. The factory spec is 0,1mm (intake) and 0,25mm (exhaust), I forget the +/- ranges. Using 0,03-0,05-0,1-0,15-0,2-0,25 feeler gauges, the best power I got was with 0,05mm (intake) and 0,05mm (exhaust) but I suspect the exhaust valve was stuck open after a hard run, the idle turned rough. Now, I'm just using 0,05mm (intake) and 0,2mm (exhaust) for safety reason and got: 130km/h static, 117,5km/h flat road, and 128km/h down hill

By the way I use only 88 octane cheap gas everyday

I'll add some pics later...

[clemence]

Now, I'm just using 0,05mm (intake) and 0,2mm (exhaust) for safety reason and got: 130km/h static, 117,5km/h flat road, and 128km/h down hill

I'll add some pics later...

Edit: the result was 130km/h static, 117,5km/h flat road, and 122km/h downhill. The 128km/h downhill was measured in different road (Mandara toll way, very steep, and I also got back wind support) it's not relevant.
I always use Bypass Ngurah Rai highway for testing because it's safer and the wind is relative calm. Here in Bali the wind can reach to more than 30km/h constantly in the toll way.

Note: the bike's acceleration, power, and power characteristic below 90km/h doesn't change at all

By the way, I use only 88 octane cheap gas everyday. No knocking, pinging, or else. Tried the 92 and 94, better but too expensive for me (the price is more than twice). The downside of using this 88 octane fuel is only that the back of the intake valve got harder carbon deposit after 20.000(ish) km. Using 92 or 94 octane the deposit is very soft and easier to clean just using gasoline and coarse cotton cloth. Tearing down the valve train is way cheaper and I can do it myself. I drive more than 100km minimum in daily basis, so, fuel cost is something to consider.
Fuel mileage:
my height is 176cm, 62kg, solo no passenger
- 61km/liter (careful, super relax driving, no more than half throttle)
- 53-55km/liter (normal relax driving)
- 39km/liter (ïllegal" interstate road race )
- 48km/liter (average normal mixed driving)

[clemence]

The pictures:


Left modified, right standard. More than 6mm more belt travel without affecting the down low ratio.


Left modified, right standard


Left modified (I stopped carving at 1mm from the margin), right standard
Next mod, I should stop at about 2mm from the margin because this way, the variator continue to push inside farther than necessary. It's useless since the belt already moved to the edge of the pulley(variator).


Modified variator. Flat file first to make the datum, then 30 degree angled round file simoultaneously. Use sandpaper only to smooth the transitions. Most of the shaping is done using files. Lots of patience required

[/ur
Standard variator


Don't forget to mill the end face of the RIGHT pulley (variator) down 0,5mm otherwise, the variator will butt early and negate the roller groove modification. Only mill the variator (the right side pulley) otherwise the belt would be off center and could break as the bent belt will run hotter due to constant flexing and bending. Mine broke at 90km/h, I was lucky the rear wheel didn't locked up for too long . As you can see from pic 1, both of the mating face of the right and left variator (the one with fan) left indentation marks (dark and rough marks. That's because I cut the groove too deep, the roller continue to push the variator. I should add a very thin steel washer between these to pressing faces to prevent the aluminum faces to chip away each time they butt together.


The humble looking working bike, ladies and gentlemen

[clemence]

Warning!!! I posted wrong instruction at 6th picture!!!
Though I wrote to mill down only the right side pulley/variator (the one with rollers inside), I marked the wrong pulley side (left side, fan side). So please ignore the marker. Just use it as preference only. MILL DOWN 0,5MM ONLY THE VARIATOR, PULLEY WHICH HAS ROLLERS INSIDE

Sorry about this guys. I hope nobody has done the error

[clemence]

maybe the moderator could delete/edit the 6th pic? Thx

[clemence]

The result:
https://drive.google.com/file/d/0B_-Da3 ... sp=sharing

[iceman]

Is that speed test on rollers or something like it? The bike is not moving so how can top speed be judged?

[clemence]

Vario125 (or perhaps all the PCX variants) has the tachometer attached to the rear gear reduction. I wrote static tacho test, that means the bike ran at center stand position and not moving. I don't have a Gopro and don't want to risk myself holding a smartphone driving at that speed. So for now, I'm not be able to report the actual driving speed in movie.

[buddy1976]

Is that speed test on rollers or something like it? The bike is not moving so how can top speed be judged?

my scoot shows 82mph on the stand, max speed on the road indicates 78mph in the ideal conditions with no headwind although my speedo is around 4mph over the gps speed.

[iceman]

That good going - expected the top speed to fall off quite a bit when under real world, real load conditions

[buddy1976]

That good going - expected the top speed to fall off quite a bit when under real world, real load conditions

I know a windshield certainly helps, it stops your body acting as an airbrake.

[ScooterMan]

I wonder how this works with an aftermarket variator? I've mentioned before that I have 3 PCX150's and that (2) have the NCY variator and drive face. One goes 79mph while the other goes 77mph. I'm thinking that one was milled slightly. I suppose it could be difference in the belt too. Although, I was using an OEM belt with only 50 miles on it when it hit only 77mph while the other hit 79mph with a new belt and is still hitting 78-78.5mph with an OEM belt (not the original) with over 1k miles on it.

Anyway, would love to get it up even a little faster, and since I'm light enough (150lbs) I think it's possible in favorable conditions in a full tuck. But, don't want to mess up an expensive part.

Also, someone mentioned recently running the 125 belt on the 150 as that would provide an increase in top speed due to it's shorter length. Might be worth a try, but if anyone has tried that already...speak up!