Hi everyone. I've been reading this forum since 2007 but this is my first post. I need help, I hope you can help me.
My 1967 Vespa SS180 (all stock) rides perfectly up to 3/4 throttle. In high revs it looses power and starts bogging. I (think I) know all possible causes and I have tried almost everything to solve this problem but I can't seem to get it right. The only thing left to try is BE2 atomizer and 190 air corrector but I am missing air here (am I?) and BE2 will just make it richer (will it?).
I've searched this forum and some other Italian and German ones and they all say that I have to use smaller main jet (running rich as you say). My current set is 160/BE3/120. I've tried 118 and 117. I also tried BE4 and BE5 mixers. I have ordered BE2 (according to some books, it should be original one) and BE1.
Stupidest thing is that when I kill the engine at high revs, the spark plug is almost perfect (B8ES), it's even a little white. So, according to spark plug, I'm running a little lean?!? OK, I've tried main jets 122 and 124. Then tried changing the fuel hose (60 cm), cleaning fuel tap, cleaning carburetor, removing carb fuel filter to get more fuel, changed the float needle.....
This is what I did so far:
- changed breaker points
- set it up perfectly (0,3 mm; 26°)
- tried different timing (from 32° down to 22°), different point gap (0,2 up to 0,5 mm)
- all kinds of spark plugs (Denso and NGK) - 6, 7 and 8 (coldest)
- mixture is perfect for idle and up to 3/4 throttle
- main jet 117, 118, 120, 122, 124
- atomizer BE3, BE4, BE5 - have ordered BE2 but...
- air corrector 160, have ordered 190...
- tried to ride without air filter, without rubber air hose, without a complete air filter housing...
- cleaned old one (one year old)
Any suggestions? Thanks!