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Second part about the derestriction of a Yamaha C3 scooter.
Edit, July 17th 2008:
Final setup, which I am pretty satisfied with:
-6x3.5 grams Malossi roller weights
-Red Doppler clutch springs
-Restricting washer NOT removed
-Grinded variator lip to allow roller weights to move a little further.
Excellent acceleration, great hill climbing, top speed on flats, no wind: 45 mph, 72 km/h.
Stiffer clutch springs greatly improve startup acceleration (0-10mph). If your C3 seem to take too long to "catch-up" it's acceleration from a full stop, stiffer clutch springs is the solution.
For details about variator grinding, check the forum at c3rider.com
Edit, June 21st 2008:
Removing three roller weights to improve acceleration (like mentioned in previous update) may not work well for everyone. Dividing by half the shifting weights is rather extreme. You may need to fine-tune the total amount of weight in the variator in order to get good results. I weight 210-215lbs, and a total weight of 18 grams in the var seem to be ok for me (stock roller weights are six grams, btw).
Someone on the C3 forum said acceleration did improved after he took off the three rollers, but he couldn't get over 40mph anymore. He was weighting 225 lbs. It seems that just ten pounds more can make a significant difference, so if you are over 210lbs, the acceleration mod may not work well for you. Someone else said he got better results using three 7grams rollers.
DO NOT EVEN TRY to just add one more weight (four instead of three). The way this variator is made requires that EITHER six or three weights be used, because any other number would cause the var to be off-balance (remember, if you use three weights, there must be an empty weight slot between every weight). Also, you may use two different set of three weights in the var (ex: three 4grams and three 3grams) for as long as you keep things balanced: when two sets are used, their position in the var must alternate.
So, with the stock rollers, you only have two possibilities for total weight: 18 or 36 grams. In order to fine-tune the var for optimal acceleration without compromising top-speed, you may need to buy aftermarket roller weights.
Once you have found the perfect total weight in the var, it could be a good idea to fill all six slots if possible, because if only three weights are used, they will wear twice faster than six weights (wear signs on rollers can be seen as flat spots on the outer circumference). For example: if, like me, you are satisfied with 18 grams total (3x6grams), then you should consider getting 6x3grams instead.
Finally, if your C3 is brand new, you should wait and complete the recommended break-in process before you remove any weight in the var: with less weight, the engine RPM are higher at low speed, thus, it would be harder to be "easy" on the engine for the first 600 miles break-in period.
Edit, June 11th:
Double the acceleration for free!
Well, maybe not double, but enormously improved.
C3rider.com member Patrickhove suggested to remove three roller weights to improve the acceleration, and I just did it. I always tought about changing the transmission gearing by using lighter roller weights, but was too lazy to actually buy them. I never dared to remove three roller weights because it seemed far too much to me, I was sure there would be great loss in top speed.
But Patrick convinced me to try it...
The results are surprising: If acceleration has not doubled, it certainly feels like it has. The C3 can climb hills much more easily, even accelerate in hills where it was losing speed before.
Top speed is the same. I left the restricting washer in, but I suppose it would make more sense to remove it now.
There is one downside: If you often travel at low speed (30 km/h or 20 mph) you will get a higher fuel consumption because the engine rpm is now quite higher at low speed.
How to do it? Very simple: Follow the videos I made, and when you take off the variator, just put three of the six roller weights back in. It is very important that the three weights left in are evenly spaced, do not put them on the same side of the variator!
It is quite ironic that the way for better acceleration has been within reach for all this time, yet none of us tought about it.
Edit June 10th: It seems that a lot of people are using my video guides to derestrict scooters other than the C3/Vox/Giggle.
Let me be clear: I am not a pro mechanic, this C3 is the only scooter I've ever owned. I used a well known derestriction method on this C3, and I learn by trial and errors, perhaps you should do the same. I don't know nothing about other scooters, so if you have something else than a C3/Vox/Giggle, then I can't help you, sorry.
If you have a 2 stroke, you should check this, though:
http://www.provoscooter.com/shop/howtovar.php
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