Modern Vespa

Hi All,

Hope everyone is having a good day! I have a VNB with a 150 Bajaj motor. Before I changed the exhaust I would say it ran pretty good. It would always start by the third kick. This winter I changed the exhaust to the SIP replica Ken Cobbing. From what I've read it seems like this exhaust keeps about the same or maybe slightly decreases proformance. When I started tuning it was very rich (I fouled one new spark plug). I got it tuned to what I thought was correct but it just did not seem like it had quite as power but I thought that was ok.

I had been talking to one of my friends who races dirt bikes about it. He took a look and said it was not revving out like a two stroke at the high end. He said it was kinda hesitating. He had me remove the filter (which I had cleaned previously). He then revved it and said now it sounds like a two stroke. I took it for a ride and now it is seriously faster than ever was (even when I had Scooter Works tune it). I have been riding it like that for the past 2 weeks (no filter) besides being faster it also starts super easy and first kick every time.

I put a new filter on it and it hesitates again so I removed it. So do I now potentially have a jetting issue? Thanks in advance for any help.

Maybe... but I wouldn't run without a filter... too much of a potential of something getting sucked down into the rotary pad area and seizing the motor.. I've seen it on a motor.. and had Hot Rod Al fix it after I bought it from the guy.