So, first attention is on its transmission. We have to find the best setup follow our body weight. Now for zoomer pgm fi, start with clutch. Zoomer has bad performance clutch, its only 2 pads installed, we have to replace it. Change your complete clutch system with yamaha's jog/zuma 50 or grand axis 100. They have 3 clutch pads and easy to repair. Jog has smaller pulley diameter than grand axis, 10mm. Jog's is find but I prefer grand axis for better acceleration. We have to add 4mm ring washer to install them and find the biggest clutch+bell clutch which can fit inside the case cover. I am used Yamaha Mio rear pulley kit and its racing clutch, but for bell clutch I have to modified its yamaha tooth spline with honda zoomer's at welding workshop. Change the torque spring with stiffer one 1000-1500-2000rpm and torque driver with racing type, this will give slower upshift than stock and don't forget to change clutch spring with at least 1500/2000rpm for better take off power. For jog's pulley we can still use zoomer's belt (always buy new belt before tuning) but for Mio's pulley use Honda Beat/Icon belt 787x18.5x30 (stock 785x18x30). Then for front pulley or variator, I recommend 2 brands, Kitaco MKIII or Polini. Kitaco and Polini have bigger diameter than stock, but kitaco completed with fan sheave, polini still use stock fan sheave. Start running test with your stock roller weight, feel the acceleration and mark the highest top speed and highest rpm that you can get. With this tuning you have to get at least 60 kph easily and top speed around 64-68 kph depend on your body weight. You have to try lighter roller if acceleration is to slow, get the best weight for roller by try, try and try. In other word, the best weight is when you've got the highest top speed, quick acceleration and highest rev/rpm at the same time, I recommend Dr Pulley slider for best result and the most important is realized that zoomer only has 50cc displacement, thanks God if you can get 70kph top speed on real flat road (GPS verified), sometime stock speedometer is about 2-5 kph faster than real speed. Kitaco and Polini variator has different character, kitaco good for city ride and polini for long distance riding, kitaco will make us easy to touch rev limit and acceleration will quite good but it is dangerous for long hour ride. Then polini will give smooth acceleration without rpm screaming, but for both topspeed almost same.
Then second, lets we upgrade the stock engine performance. The little Zoomer PGM Fi stock engine actually has good performance than stock carb type one, but performance upgrade will take more dollars than carb type. I don't recommend yet for big bore piston, beause the risk is too high compare to only 9cc increased (49 to 58), my experiment at the past for my other scooter gave me 2 times engine broken because of big bore(113 to 125, 163 and now 155cc). The engine will over heat for long distance or daily ride, big bore will worth for race purpose only which take just 1-2 hours ride. Don't do too extreme modification with this fuel injection engine type, just do the safe way only. Increase the rev limit by Polini or Kitaco imap, both work good. For my zoomer, I installed Kitaco i-map to increase rev limit 10000rpm (stock only 8000rpm) after replacing polini cdi because its some problem after few months, kitaco is better for long use. I installed too Andrion IM8 kit (Indonesian local part) to increase the torque power. Don't forget to replace our stock TCI coil with bigger one, I used Honda VFR 800 coil(TEC MP-06), this better also. This ignition parts combination will give more power and you will really satisfied, I guarantee, you will get wider power band for this tiny engine. The only problem is the Andrion IM8 kit only available in Indonesia market, Mr Andres, the genious guy, this kit creator is very helpfull to guide me about how to increase the injection bike power with only cheating the ECU/ECM. There is another kit for power increase, dynoboost AFR tuner, but this only made richer AFR ratio and didn't give significant improvement.
Third step, replaced the stock exhaust with racing free flow type, this will help a lot for tuned engine. And replace the stock air filter with thin sponge or foam type to let the engine breath better.And theThe last step is find again the best roller weight for this final setup, see the first step above, if your result is more than 2 gram lighter than stock it means your engine power is bad or your body too heavy, but if you get stock weight or heavier it means your engine is really powerful. But again, this final roller weight theory will works for approx 75 kg guys, for heavier than that will need lighter roller weight. If you feel the engine power is enough to change your final gear ratio, do it, may be kitaco and honda Metropolitan gear are too heavy ratio, my suggestion build it at good lathe workshop with maximum ratio 3.23 (Kitaco 3.15 and stock 3.50), finally you will get more top speed, faster acceleration, better take off and powerful on hilly road with only based on stock engine. Happy tuning !
This blog is only base on my own experiments, I just want to share with you all, hope can help you before doing performance tune.
