PCX Tuning 64Mph Cap

[patmacessex]

Hi All i've been scratching my head and I have something that just doesn't make any sense and it drives me nuts....
I have a 125CC PCX 2016 Which has a Malossi 170CC upgrade this comes with the Malossi Force Master 2 which is a controller on the Fuel injection and the TP.
All is working but here comes the head scratcher... The bike refuses to go over 64 MPH Now all of you who have some experience with the PCX will shout at me "IT'S THE REV LIMITER" But no it isn't.... I changed the gears first of all to the default 150CC Setting which is basically replacing the 47T with a 44T which gives you a cool 64Mph I expected that... So when I was driving and it did 64/65/66 /67 GPS fair enough.. Now I have been playing with the gear ratio and what ever I do it sticks to 64 Mph at the moment it's on a 42/16 Gear ratio which should give me well over 70Mph but the bike just sits at 64Mph doing nothing e.g low revs... So there should be a restriction on the bike I'm not seeing or just can't find... Any ideas? By the was 64Mph is GPS Speed on the phone not Speedo meter speed...

[Mel46]

I am not the expert on this forum, but I can say that, though I have a 150cc, once I changed the variator so that the belt could go out farther, the top end went from 64 - 65 mph up to 74 - 75 mph. So, you MAY be restricted by the variator.

Still, as I said, I am not the expert on this forum.

[Gil]

As mel46 suggested, what variator kit do you have? Also what roller weights? Remember that the stock engine makes most of it's power at 8,000 rpm. I'm not sure what you're power curve is now with the 170cc kit, but it might have the peak power at the same RPM.


This Dyno run from one of our forum members shows how the power drops down at red line. Also what did you do for fuel management?
viewtopic.php?f=9&t=7303

[Gil]

The Dyno image from the thread does show the RPM. At 8,000 RPM is where the engine makes the most power. He also had heavy variator weights and you can see that he is at redline when his speed on the Dyno is 110 kmh.

Here is another thread talking about the variators.
https://www.hondapcx.org/viewtopic.php?f=9&t=7479

[patmacessex]

Thanks for the replies... First of all the variator I'm running on a malossi multivar 2000 with a kevlar Malossi drive belt I also have sports (Yellow) clutch springs and the yellow short contra spring I've put 12 Gram rollers in there. Nw to rule out the variator I changed it to the standard honda vario with all the stock springs and a brand new drive belt Top speed is the same. Now the fuel injection is handled by the Malossi Force master 2 which comes with the bore kit I wrote to malossi and they said change the mapping on there which I haven't tried yet. Also if it is true what you say about the 8000RPM then surely changing the gear ratio should have some impact but nothing changes not a single mile increase or even decrease....

[Gil]

I looked up the Malossi Force master 2 and it looks like it has a few different maps, but most importantly two fo the maps are for the 150cc big bore kit and no map is tuned for the 170cc big bore kit. I'm not too well versed in tuning, but I do know that the fuel ration and ignition timing are important. It could be that your engine needs more fuel, or less, at the higher rpm range. A local motorcycle dyno might shed some light on how your engine is tuned. At 170cc, you scooter should be up too 74 mph on the highway. The redline limited top speed on my scooter is 74 mph, only on a steep downhill or a strong tail wind LOL.

[Gil]

I think I found the kit that you installed. Looks like it is a 170cc paired with the malossi controller that you have. It also states that it has a higher redline than stock.

https://www.malossistore.eu/bw/alum-com ... c12518-M-P

[Mel46]

Our founder put a 170cc kit on his 125 and it definitely went faster than 64 mph. I will see if I can find his How-to. I am pretty sure he wrote one. There was a lot written on them back when this forum was young.

Here is one posting of his.
viewtopic.php?f=9&t=2252&hilit=170cc

And another.
viewtopic.php?f=9&t=4559&hilit=170cc

And another.
viewtopic.php?f=19&t=4471&hilit=170cc

And this one.
viewtopic.php?f=19&t=3204&hilit=170cc

[Mel46]

And another, but you get the idea. There are/were several "whisperers" on this forum who had done it all to their bikes. Hopefully some of the are still around and can give you guidance.

viewtopic.php?f=3&t=2939&hilit=Big+bore+kit

[patmacessex]

Yes Gil thats the kit I bought bu like I said before mapping no difference it is like something is restricting the bike and when I find what it is all the power will be released if that makes sense at the moment nothing i change makes a difference gear ratio no difference mapping no difference it's like it somehow stuck or held back.... Like others said 74Mph is not too much to ask with this set up... and I would expect a difference if a negative one if I make a change but nothing I do changes anything....

[Scootyman]

Are any of the others that have fitted the kit and done the mods you have based in the UK? I'm wondering if its something to do with the UK specific model and particularly the VS sensor located in the gearbox housing that's sending a speed signal and restricting your speed. Does your scoot accelerate better than before and feel like it has more power, just it stops like its a speed limiter fitted?
Something similar is occurring for a friend with a Zoomer FI that has a Kitaco imap fitted and the consensus was it was the software not removing the injector fuel cut off at the standard rpm limit.
It might not be but if you have added power and performance up to the top speed and then nothing more, I would say that sounds like an electronic limiter still kicking in somewhere. If you search for a company named DILTS in Japan, they make a unit called Enigma which is a fuel controller. Have a trawl around their site and you will find lots of info spread around the site. It might not be specific to PCX either but it applies as some of it is generic. You will need to translate with Google etc but it may be worth your while. I have been doing similar stuff to a Vision 110esp around fuelling etc and the DILTS website helped with the knowledge side of things.

Hope that might help a little

[Gil]

@patmacessex Any other UK riders here with 125cc PCX?

[Oyabun]

Wohoo... Finally a topic I'm interested in. Seems that I have to check back to this site more frequently.
I have a heavily modified pcx with a Yuminashi high compression big bore kit, large throttle body, larger fuel injector, big camshaft, altered gearing, Malossi multivar 2000 and other goods and this is my sexond pcx with a big bore kit.
As for electronics I've used a simple engine temp cheater variable resistor on the first, the went the Dilts Enigma and later the APItech fuel controller way, but I don't know the malossi fuel controller.
All have their limitations, and don't really good without proper fuel mapping on a dyno.
Having said that, I'd start by doing some data logging. If you buy a cable (lonelec.co.uk) to connect to the bike's diagnostic port, and mate it to a bluetooth obd dongle what is able to communicate the ISO13040 protocol what the ecu talks, then you can use an application on your phone (e.g. Torque pro) to log all the parameters from the ecu. This will give an approximate lambda reading, a very accurate RPM, engine load, coolant temp etc.
From this data it is possible to start troubleshooting your issue.

[Marko]

I bought a scanner cable from lonelec.co.uk, it didn't work, wouldn't connect to my Foxwell scanner.
I emailed Lonelec, they took a week to answer and just said that it may not connect to all Honda motorcycles. £22 down the drain. Don't bother.

[Oyabun]

Marko, just use a cheap ass Bluetooth dongle what is capable of K-line communications. Mine was like 6usd from eBay.
Works like a charm

[Conelite]

Marko, just use a cheap ass Bluetooth dongle what is capable of K-line communications. Mine was like 6usd from eBay.
Works like a charm

I bought the Kitaco OBD adapter and I could not get any kind of scanner to work including one of those bluetooth dongle. It see's power but no data transfers.

Screen Shot 2020-11-12 at 3.54.04 PM.png (242.04 KiB) Viewed 5769 times

[pcx888]

Did you ever get obd2 to work. I cant get mine to communicate I have a 2011 tho.

[Conelite]

Did you ever get obd2 to work. I cant get mine to communicate I have a 2011 tho.

Nope, I gave up.