I have been working on a 2000 SR50 for many months now and just can't figure out why it wont rev out and run better than original. I am a relatively knowledgeable mechanic and have even written an article for putting a kit on a LX50 on ModernVespa.com.
Back story - it took me many weeks/month to get the right parts from Germany. They sent 2 Morini barrels (70cc) and Morini exhaust, before I got the right parts for a Minerelli. The kit is a Motor sport kit (70cc), looks generic/not polini or molossi. That is what Scooter Center Germany offered up.
So at this point it is all together. On the center stand it revs out great! But under load, it is boggy and hardly runs well. I almost have to choke it to keep it running.
I have changed rollers to 3 different sizes. I checked the belt to be the right size, still using stock belt (may be problem). I have ridden the scooter for 10-20 miles and ran it for additional hours, so I think it is broken it at this point. Enough where it should have power off the line. Another weird thing is the power bands are crazy curves. A few spots were it does start to have power. Finally, it I am going down a hill and it can rev up, the power really does kick in.
What I am thinking it could be at this point:
1. Carb - Maybe I need to upjet more, I upjetted a bit. But I wouldnt think it would rev on center stand if jetting was off and the spark plug color is nice. Or maybe carb is dirty or flow/float issue.
2. Belt - maybe the belt is slipping, too much power for stock belt????
3. Leo Vinci Exhaust - maybe there is something wrong with the exhaust. I have not tried putting stock exhaust back on yet. I did cut the restrictor out.
4. Is there anything weird with the CDI or a computer control?
The customer has been really patient with me and this horrible project which should be an easy bolt on, gas and go. But we are both very frustrated and angry at this point.
Thanks for any knowledgeable help and hopefully someone has experince with this.