How to make a scooter accelerate faster by tinkering with the variator

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 decided 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.

Let´s 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%)