Speedy Gonzales, Road Runner and the Red Rocket

Optimizing the Piaggio MASTER 500cc CVT part I

the last one is with a hat tip to Matt and Tray from South Park...

I read a lot about how to improve the acceleration of the Piaggio 500 cc MASTER engine.
There is the:
J. Costa Variator
Malossi Multivar 2000
Polini Variator
Dr. Pulley Sliding Roller Weights
Malossi Racing Spring Set
Malossi Maxi Fly Clutch
Dr Pulley HiT Clutch
and so on

I wanted to go with the Dr. Pulley sliding weights because it is the cheapest mod with the most impact for the money, but first I needed to know if I had the old 6 roller variator or the new 8 roller type.
So I opened the variator assembly to see and wondered what impact removing 2 rollers would have. I read in different boards, if you change the weight of the rollers you should not go below 8% of the original weight. I wanted to try an extreme setup to see how big the impact on acceleration and gas consumption would be.

The Mustang Conversion

I put the variator assembly back together with only 6 rollers and did some testing.

Let´s measure the acceleration:
0-60=6.5 sec
0-80=8.5 sec
0-100 ca.12 sec

I did the measurement myself. Looking on the street, on the speedometer and in the right second press the stopwatch on the right hand with the left is kind of not so good an exact. I did all runs at least 4 times since the street is a very slight grade. So I did it up and down at least 2 times. Add roughly 90 kg weight to the 210 kg from the Spidermax and you have 300 kg that needs to accelerated.
Here is the speed to rpm ratio with the 6 roller setup.
 60 km/h  = 4000 rpm
 80 km/h = 4500 rpm
100 km/h = 5000 rpm
120 km/h = 6000 rpm
140 km/h = 7000 rpm
160 km/h = 8000 rpm

The acceleration improved nicely but there is still the first 2 seconds what the engine needs to rev up what feel kind of sluggish but then you really feel an improvement. I needed to throttle down much faster than normal because I reached the desired speed.
While the normal acceleration was in the 4000+ rpm it is now in the more torque friendly 5000+ rpm band. Mostly the Spidermax is then already above 50 km/h.
Now lets see how much the gas consumption jumps up.
I used exactly 1 tank full. I filled her up to the brim last time and did the same this time.
She used exactly 5.02 liter per 100 km compared to around 4.8 I have normally. So we are talking around  4% higher consumption, but then I drove a bit more aggressive because it is just too much fun with the stronger acceleration.

She has a faster acceleration but there is still the first 2 seconds where she feels a bit sluggish. After that you have the wohaaaaaaaaaa feeling and need to throttle back because you are already at 70 in a 40 km/h zone.

 The Colt Conversion

Now let´s go crazy!
How about we remove 2 rollers more. Yupp you read right - reduce the 8 roller original setup to 4 rollers. Will the Spidermax run at all or just in very high rpm? Will she be usable at all on the street and in what astronomical regions will the gas consumption skyrocket?

The test setup with 4 rollers
and this time I rigged the stopwatch to the handlebar for a more secure and faster usage.

The acceleration changed to:
0-60=6.5 sec
0-80=7.5 sec
0-100=10.3 sec

 Here is the speed to rpm measurement:
 40 km/h = 4000 rpm
 60 km/h = 4500 rpm
 80 km/h = 5000 rpm
100 km/h = 5500 rpm
120 km/h = 6000 rpm
140 km/h = 7000 rpm
160 km/h = 8000 rpm
These measurements are not very accurate, since even the slightest incline or decline changes the rpm. At 100 km/h you can be at 5000 downhill or 7000 accelerating uphill. The instant response is amazing since above 40 km/h the MASTER engine is already in a good power band torque wise and 18 of the 40 horses are engaged. Rip open the throttle and she jumps eagerly in an instant to 5500 rpm and above.
28 out of 40 horses are pushing you back in the seat while the maximum torque is already reached at 5000 rpm.
In the range from 30 to 100 km/h it is the feeling you have if you got the next bigger engine. No not the 850 cc think more the Burgman 650. (I have to find me a Burgman 650 and race her)

Even if the 4 roller  setup seems much faster from the start the measurements from 0-60 are identical with the 6 roller setup. The main problem is that 300 kg need to be accelerated from stand still. The first 2 seconds it just needs to rev up the engine, engage the clutch and get moving. So the only thing to improve that would be a different clutch setup what engages at higher rpm.

The fluctuation in rpm is with the 4 roller setup the highest.
While with the 8 rollers setup when you open the throttle full above 40 km/h you jump in the mid 4000 rpm in the 6 roller setup you jump into the mid 5000 and in the 4 roller setup you quickly jump into the 6000 and soon higher.

The response is with the 4 roller setup instantly. Tested the twisties today with my honey in the back so 370 kilo incl. luggage. The response in the very slow to drive (5 to 10 km/h) hairpin curves uphill was absolute glorious. Instant power, no strangled sealion (that dreadful squealing noise when the automatic clutch has not engaged fully and still slips) except once in the worst steep, tiny hairpin curve. I also noticed that there was no more paint shaker (the shudder when the belt flops up and down and you feel vibrations because the rpm is to low for the and you do not have the torque you need).
The whole behavior is now much more civilized like a fine tuned Japanese engine what is now optimized for acceleration.

I wrote in Test Track:
The Spidermax has the most talketive motor. From the sound of an old farming tractor (20 km/h 2800 rpm uphill) to the sonor sound of a big thumper bike you hear a wide variety of sounds. She always lets you know how she feels, the Italian girl. Also, she does like her vibrator, the Burgman and even the Pegaso dampened vibrations better. It is not too bad though. She is also not too fast getting up to go, but that might be improved with a different variator. She has the same engine as all Italian 500 cc Scooter. I had the feeling the Burgman was a bit faster from the start.
With the 6 and 4 roller setup, you can strike the above paragraph!
The 20 km/h uphill are now around 4000 rpm and she runs smooth as a greased pig.

Also the acceleration with a pillion is now even more dynamic than with the 8 rollers solo rider. From a near stand still in a roundabout you have now no painful second or two until the speed is there to make that gap. It is there in an instant. From the stand still at a roundabout if you crank up the rpm a bit before start you are much faster also.

Lets see how high the bill on the gas station is for that...
I filled her again to the brim at the same gas station and needed 12.51 liter. With that I drove 261 km. Around 110 km were 2 up into the mountains, 100 km highway with speeds between 120 km/h and 140 km/h slightly hilly and some wind and 50 km urban roads with in town traffic. No red lights, no stop and go. The 150 km were just me. So if I did the math right my gas consumption on this ride was back to my normal 4.8 liter per 100 km.
WOW - somebody pinch me.

I will definitely leave the 4 roller set up and will use at least 2 more tanks to be sure about these results.
I will update this post when I am back from the gas station next time.

next time 1:
204.6 km and 10.41 liter makes 5.1 liter per 100 km.
I went into the mountains and I never had so hot brakes driving up hill. ;)
After 50 km into the mountains, I went the rest on the highway with speeds 120 to 140 km/h. I really rode her hard this time and compared to what she normally uses, that is the normal millage for this kind of riding style, should have even been a bit higher.

next time 2:
215.1 km and 9.82 liter makes 4.56 liter per 100 km.
This tank I rode within the speed limit always. No full throttle starts and all in all very conservative and leisurely riding style. 2 up into the mountains and some highway and rural roads.
This is one of the lowest consumptions and it proofs, that the 4 roller Colt conversion has the same gas consumption like the standard 8 roller setup (see chart below).
If you ride aggressive you pay around 12% max more at the pump same with 4 or 8 rollers.
next time 3:
272.4 km and 12.92 liter makes 4.74 liter per 100 km. Normal riding conditions. Oh and I made the 20.000 km today too. So happy birthday (or so) Spidermax.
So the fantastic news is, that the 6 roller Mustang conversion or the 4 roller Colt conversion does not use more gas than the standard 8 roller setup!
(You probably will use a bit more, because you riding style will definitely change but it will be in the area of 2%- 5%)

Here is a comparison how thirsty she was with the factory setup.

I will monitor the gas consumption now for a while, and so can you. These are the actual millages I get and it will be automatically updated every time I am back from the gas station. If you click on the millage below, it will bring you to my logbook.
on the right column you find the consumption and the logbook from the factory standard 8 roller setup.

I will log down in this post any problems or observation I make regarding the Colt conversion. You will find it at the end of this post.

Since I changed her from this, the good girl next door,

to a fiery red head red rocket,

it is not only much more fun to ride her, I also ride her different, much more sporty ... (ahem -  have to watch my mirrors permanently for bears and often have to slap me on my hands because I am already speeding again ...)

I am glad I could give her and me the temperament to match her color.
So I guess the right color for the bike is an important thing. Sadly Malaguti just makes her in boring colors.
But then, 4 spray cans, some masking tape and old newspaper is all you need to have it your way.

Now let´s have a look at the MASTER engine to see where the torque and the power is.

She is the power plant in these nice scooters:
Aprilia Atlantic 500
Aprilia Scarabeo 500
Gilera Nexus 500
Gilera Fuoco 500
Piaggio Beverly 500
Piaggio MP3 500
Piaggio X9 500
Peugeot Satelis 500
Malaguti Spidermax GT500
Malaguti Spidermax RS500
and more...

Power and torque range MASTER engine 500

The different acceleration areas regarding to the number of installed rollers.
It is not very accurate, but gives you an idea where the extra speed is coming from.
Vertical scale corrected (Piaggio had an error in it, see original above)

There is no reason why this setup should not also work fine with the 400 cc Piaggio engine. It is the same engine just the bore is reduced from 94 mm to 85.8 mm and the stroke is reduced from 71 mm to 69 mm.

I try to figure out, why the gas consumption does not go up even if I use every chance to let her bolt. The only explanation what makes sense to me is that she instantly is in her optimal torque band and does not need to go there from 3000 rpm as in the standard 8 roller setup.
If you have any other ideas or want to talk to me, use   to talk to me.
Famous last words:
I often read that people who enjoy riding their scooter have a big fat smile on their face.
Well, I enjoyed the Kymco, Burgman and now my Spidermax and once a while I crack a grin but that big fat smile I could never fathom.
With the Mustang conversion the big fat smile was there after the first minute and did not wanted to go away.
With the Colt conversion it is accompanied by the occasional WHOHOOOOOOOOOO and it is so much more fun to ride that "new kick ass sports bike".
So is everything now only speed an performance? Will you just have a race horse instead of a medium tempered one? What if you miss the "strangled sealiaon" calling for you once a while?
 Never fear. If you just crank the throttle a quarter to a third you have you old bike back.
The paint shaker and the "strangled sealion" will be with you instantly. In fact for my 3rd test tank full I am doing just that.

Why the funny names?
Well the 6 roller setup reminded me of a wild (Ford) Mustang what enjoys to run.

The 4 roller setup what is even more dynamic and jumps to action at the smallest movement of the wrist reminded me of a young horse (colt) what bolts away just for the fun of it.

To better understand what I did it is important to know the roller weights:
Original are 8 rollers a 18 gram, so that is 18 gram x 8 = 144 gram combined roller weight.

You can get rollers for tuning in:
16 gram x 8 rollers = 128 gram total
15 gram x 8 rollers = 120 gram total

What I did is:
6 rollers is 18 gram x 6 = 108 gram total
4 rollers is 18 gram x 4 = 72 gram total

I just reread this posting and stumbled over an inconsistency.

I did not have a precision scale when I wrote this to check on the weight myself.
A year later I have one and 4 rollers add up to 85 gram what what makes one roller 21.25 gram and not 18 gram.

It seems the original rollers are 21.5 gram, what accounts for the missing 1 gram of the plastic which I removed during the woody conversion test from the outside of the plastic.

So the paragraph above would be correct read:
What I did is:
6 rollers is 21.25 gram x 6 = 128 gram total
4 rollers is 21.25 gram x 4 = 85 gram total

 I got these information from my friend Sloper from Bella Italia and he warns that the higher rpm are not good for the motor. Since he has the chance to run the MASTER 500 in his Spidermax at full speed, I concur. But in my case the speed limit is 120 km/h and I am seldom above 7000 rpm.
I noticed when I did the 160 km/h test that at exactly 160 the limiter was cutting the acceleration since I reached 8000 rpm. With the 8 rollers I could get to 165 km/h. But I am much happier with my 4 roller setup.

So if you want to try a Mustang or Colt Conversion on your bike, be aware that bad things can happen. So don`t blame me for exploding motors, speeding tickets, facial distortions due to permanent grinning like an idiot, that your spouse left you because she won the lottery or any thing else. If you fiddle with your bike it is your responsibility.
Update after 1500 km
It is so much more fun to ride with her even with a passenger in the back. Today on the highway I had some situations where the extra power was very welcome. Passing a car and accelerating from 100 to 130 is much more fun now. In the roundabouts with stop and go and the sprints to enter the roundabout is much more snappy now. While with the 8 rollers I had to open up for the first quarter of the roundabout, now after half a quarter I have to throttle back to not get carried out of the roundabout because of my speed I already have.
After spending the last 2 tank fulls with high speed on the highway (interstate / Autobahn) and that with lots of wind first in front so that with a full throttle sometimes not more than 130 km/h was possible and later with it in the back the consumption is between 5 and 5.25 liters per 100 km what is the same if I did this kind of rinding with the 8 roller version.
Oh we have warm days here around 30 degrees celsius and with the sun around the whole day and the bike really getting hot on the highway I noticed the strangled sealion  when I have to accelerate slowly and are below 3000 rpm once a while. It is way not as bad as before but when the clutch bell is hot and the acceleration is slow then a light screaming is there.


  1. Hey would you happen to have a Solidworks model of this engine?? as i am working on a project involving a Piaggio MP3 400cc

  2. sorry ray, I don´t have a Solidworks model

  3. a few years ago i had this engine in my fuoco.
    now i have a majesty 400 and was having some troubles with the dr pulley sliders flipping over (probably installed wrong by myself).
    but then i remembered your mustang/clot mod on the vario and tried it out on the majesty.
    6 out of 8 in total stayed in (original rollers,i beleive 18grams) and it's working super! don't know if i'll go test again to install the dr pulleys correctly :-p
    thanks for testing and writing this very long lest ride of about 55000km!
    Ciao, Hannes from Belgium.

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