I bought an agility 50 about a month ago. Stock, it had a hard time climbing hills, accelerated slowly, and was restricted to a max speed of 30 on the speedometer (25 MPH by radar/GPS).
With 4 quick mods, done 1 at a time, I've seen a complete transformation of the bike.
1. Unrestricted CDI - bought one on eBay as part of kit (CDI, smooth boss, variator weights, and bigger main jet for about $40). Quick plug and play installation. Immediately the engine revved higher and faster, presumably from a different fuel mapping curve. And with the max speed de-restricted, down hill max speeds reached about 40 on the speedometer.
2. Smooth Variator Boss - part of the same eBay kit. (Also bought an impact wrench and metric set of bits for about $80 total, in order to remove the nut on the variator.) This mod has a big impact when you are full throttle on a limb flat. Allowed me to hit 40-45 MPH on the speedometer on long flats.
At this point, the bike felt a lot faster, but acceleration was still slow and uphills were embarrassing. The bike would crawl up a hill, leaving me with cars honking at me and passing in frustration.
3. Dr Pulley 6.5g variator sliders - ($20 on Amazon) these were a quick swap from the stock weights. Immediately made the bike change speeds more responsively and with a smoother power band. Up hill went better because of faster entry speed from better low end acceleration.
4. 1500 RPM torque spring - ($9 on Amazon for a yellow spring) this required me to buy some additional tools like a 39mm driver. But made a huge impact on the bike. Revs much higher before clutch engages. This gives a big lift on torque off the line and completely fixed the uphill issue.
Now top speed is slightly lower at about 45 MPH on the speedometer (37MPH on GPS/radar). However the bike easily maintains 30 MPH at all times, including when going up decent hills. There's one monstrous hill on my commute that slows it to 20MPH, which is really not too bad.
Overall, I love the pairing of the 6.5g sliders and 1500RPM torque spring.
Did all the work myself and happy to provide tips on completing the work to any community member with questions.
