The 0 Euro Tuning - Piaggio MASTER engine 500 cc -

Optimizing the Piaggio MASTER 500cc CVT part II

The facts and measurements how to make her accelerate faster
2000 km after the Colt Conversion (see posting before) I wanted to know how much more the real increase in acceleration is.
So today I put the 4 rollers I had removed for the Colt Conversion back in the variator and did some measurements.
Sounds like gibberish to you so far, please read first this post.

OK let me tell you how it actually feels driving with the unmodified engine again. 
After being back to the original 8 roller setup, I have the feeling I drive a my old Volkswagen Jetta diesel again.
Compared to the sports car feeling before with the Colt Conversion.
Passing cars in some situation gets kind of risky again.

But to get as much comparable measurements as possible and as exactly as I can, I will "suffer" for sciences sake a few days longer.

UPDATE one day later

Went into the mountains today to get an idea how the bike normally behaved. After a couple months and 2000 km with the Colt Conversion I had forgotten how bad unmodified was before.

I took a leisurely stroll with my significant other in the back and we were just enjoying our selfs in the speed between a 50 cc and a 125 cc. (Yes, sometime I like to ride just slow to enjoy the scenery.)
Oh my what difference it was. The paint shaker was omni present because of the rpm´s which stayed in the 3000 band.  The poor belt was constantly flapping around and beating down on the anti flapper wheel.  In one little stretch slightly up hill at 40 km/h when the rpm was at 4000 and I opened the throttle full I could not believe my eyes.
The acceleration was something like this: 4000 rpm - wait a second - 4100 rpm - wait a second - 4200 rpm - wait a second - 4300 rpm - wait a second -.
This was apparently the worse case scenario I just hit there by bad luck.

Remember we are talking mountains and twisties and hair pin  turns here.
I tried several situation where at a speed between 40 and 60 km/h a ripped open throttle should provide some sort of acceleration and it always was very bad. The rpm always climbed slowly in the 3000 and 4000 band. So the main problem with the 8 roller original setup is that there is no fast moving up in rpm as we have with the Colt Conversion and a little bit more moderate with the Mustang Conversion.
Let´s get back to my old Jetta Diesel with the comparison for a second. Since Piaggio decided that the MASTER engine should stay in the low rpm´s you are often in the 3000 to 4000 rpm band. At least riding moderately inside the town. The MASTER engine but is happy in the 5000 rpm band and above. That is where she has the maximum torque and runs smoother than in the lower rpm bands. While in the lower rpm bands she shows that she has to work hard - with noise, vibrations and a not stellar performance the moment she is in the upper rpm bands it is like the turbo kicks in and she purrs away.

So, are there any drawbacks so far?
Well, the engine runs hotter since the rpm are higher and I think I noticed a slightly change in the color of the stainless steel exhaust from silver slight brown to a little darker silver slight brown, but I am not sure about that.
With the next oil change I will switch to full synthetic motor oil to be on the safe side here.Hah, the next day the change oil came up and I have her now on full synthetic 5w40.

Since the 3000 rpm band is seldom used with the Colt Conversion and even the 4000 rpm band is mostly used in the upper area there is virtually no vibration anymore. So now I noticed a slight vibration in the 6000 to 6500 band. The funny thing is that it is changing the vibration speed even if the rpm and the speed stays the same. It is not bad but it is noticeable. Checking with the 8 rollers setup there was a bit vibration there too but lighter.
There might be an issue with the metal plate where the rollers press against to move the variator.  I will investigate further and will update this posting here if I find out more.

During my 8 roller test I left the silver noise cover off from the tansmission case. This results in a better cooling of the clutch and the strangled sealion was nearly absent during this ride.

Transmission cover and the foam noise dampeners.

You can see clearly where the air holes are covered (black area on the white foam) and that there is no air intake filter anymore what they had in the first model of the MASTER engine.

With the silver plastic cover removed it is quite easy to check in what shape the belt is in if you look into the bottom center air holes.

With the cover installed the clutch and the driven pulley just have the lower back opening to expel hot air. With the cover removed, the air flow is out of all holes around the clutch. This way the heat is much faster removed and also the metal lid expels the heat much better than with the plastic cover installed. So the screaming clutch (strangled sealion) is less likely to happen because the heat is much faster removed. The drawback is, you hear the transmission noise a bit more and I do not think it is a good idea if you have rain where you are riding. With nearly no rain here in the south, I opt for better ventilation and leave the cover off.

Airflow with and without (orange arrows) silver plastic cover

... and yes, I know the air intake looks a bit ugly, so I will look for a nice cover. You will see it here if I find a pleasing solution.

Now let´s have some numbers to get an idea how the different roller setups work out.
acceleration - 8 rollers - 6 rollers - 4 rollers
0- 60 km/h - 7.00 sec - 6.5 sec - 6.5 sec
0- 80 km/h - 9.50 sec -  8.5 sec - 7.5 sec
0-100 km/h - 14.5 sec -  12 sec - 10.3 sec

speed - 8 rollers - 6 rollers - 4 rollers
020 - 2100 rpm - not measured - 3000 rpm
040 - 3000 rpm - not measured - 4000 rpm
060 - 3700 rpm - 4000 rpm - 4500 rpm
080 - 4500 rpm - 4500 rpm - 5000 rpm
100 - 5200 rpm - 5200 rpm - 5500 rpm
120 - 6000 rpm - 6000 rpm - 6000 rpm
140 - 7000 rpm - 7000 rpm - 7000 rpm
160 - 8000 rpm  - 8000 rpm - 8000 rpm

What these numbers do not show yet, is the extreme acceleration when the bike is already moving. I will do some additional measurements in this area.
acceleration - 8 rollers - 4 rollers
20-60 km/h - 5.1 sec - 4 sec
30-80 km/h - 7  sec - 5.3 sec
40-80 km/h - 6.7 sec - 4.6 sec
40-100 km/h - 10.0 sec - 7.1 sec
60-120 km/h - 14.5 sec - 9.8 sec

All measurements were done 4 times up and down the same road and were repeated if there was a noticeable difference.
The speed was read from the speedometer. The speedometer was checked for accuracy via the gps see here.
The Spidermax with the rider and the add ons was around 300 kg.
The air flow was checked on the center stand with the engine running in different speeds and the hand in front of the holes.
Update 2009.09.18
Even with the 8 roller standard setup and the silver cover off there is virtually no screaming sealion any more. So the cover will stay of permanently. I just need to find a suitable cover for the air intake.Rummaging in my garage produced this vent cover.
It has exactly the right size to clip into the hole from the air intake.

It just needed to cut off a bit and the 3 tabs from the clamps needed to be shortened too.
Since 3 stores did not have my non glossy black, I painted it in the bike red.
I think I might like that even better than black.

Update 2009.09.30
After not hearing the "strangled sealion" since I took of the silver cover from the transmission no matter in which extreme situations I wanted to test my clutch bell air cooling theory.
Under harshest riding conditions I tried to produce a single noise from the clutch. With barely 3000 rpm and a speed between 10 to 20 km/h I drove like a snail up hilly streets. No matter how hard I fried even with rpm below 2500 there was not a single squeak or squeal to hear. Testing the clutch bell after 10 min ultra slow climbing through the air holes carefully with a wet fingertip produced a hissing sound.

So the clutch got hot during the abuse but the air cooling prevented any too high temperatures and the strangled sealion is now gone for ever.

If you have problem with the noise (thinking of the Burgmann  AN400 K7) and all the other scooters where I read about similar noises, the solution is simple. If you have a cover remove it to test if your problem is gone. Uncover the air holed and if you do not have any, see if you can make a few to help the clutch to get better cooled.
Update 2009.10.02
While riding I got an idea how people who have to ride in wet conditions can improver the clutch cooling without loosing the silver plastic cover.

Here you can see the foam what covers the air holes. You see also that the foam is pretty thick.
One way would be just to drill six 10 mm holes through the plastic cover where the 3 big upper and lower holes are covered by the foam.

If you do not want to drill holes into your cover, just remove the yellow marked area of foam carefully (so you can stick it back in case you want it). These are just the lower holes from the clutch vent but they also are close to the central bottom vent ( the 6 cut outs you see above). This should already get enough air flowing to cool the clutch and eliminate or at least reduce the "strangled sealion" noise.
Drop me a line if you tried it and tell me how it worked out for you.

Update 2009.11.07
5000 km with the Colt Conversion

Here is the log from the gas station, some times I forgot to log an entry but they were all in the same range.

The median consumption is 4,84 l/100 km compared to 4,77 l/100 km with the original 8 roller setup. So that is next to nothing if you consider the more sporty way the bike handles and gets driven.The belt change came on with 24000 km and since the belt still looks the same as 5000 km ago it will not be replaced. I will check at 30000 km again but I think it will be good for much longer - even with the bit higher stress on it because of the Colt Conversion.
The roller plastic shows a bit more wear but that is to be expected since 4 rollers have to do the work from 8.
When I check the state they are in, I think they should last another 24000 km without a problem and if the plastic does not disintegrate, for much longer.

So the belt and roller change every 12000 km is in my eyes a very unnecessary step. Both should last easy 30000 to 50000 km depending on the riding conditions.

The lower vibrations ( paint shaker around 2800 rpm)  are gone 100%. The whole riding experience is very joyously with the Colt Conversion and no ill effects can be reported within the 5000 km test.
There is no question that I will stick with this setup until some problems should arise, what I really doubt.
Update 2009.12.08
Ending the strangled Sealion the simple and fast way

I tried the removal of the yellow marked foam piece and then took the silver lid back off to see the way the air can flow. After that I decided, that the whole foam would be unnecessary around the clutch area.

So I removed it all, just left the foam strips what cover the belt area. The result is promising, no more squealing, the clutch gets sufficiently ventilated.
Problem solved!
Just take the 4 screws off to remove the silver cover, remove the half round foam stripes completely, screw it back on, that´s it.


  1. hello friend I have a mp3 400 what kind of belt I need and where I get the 4 roller variator thank you.

    1. You just use six or four of the original weights


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