Modern Vespa

Hi everyone, first time user. I'm stuck .I want to purchase a new exhaust for my vespa sprint vbb 1969. I'm torn between the bgm bigbox touring or the sip road 2. I have fitted a pinasco 177 kit and had the scooter converted to a vespatronic 12v system. My next step is the exhaust, I want to be able to cruise along at a decent speed and maybe now and the take a passenger. At the moment my scooter doesn't sound well at around 40 to 50 mph .sounds like its screaming but I know there more life in there . Also do I need to change the main jet

Can a mod move this?

I'm leaning towards the road as the box is smaller than the BGMs I've seen. Don't want to bottom out in turns etc.

As far as upjetting. Yes!!! Tell us what size carb you have and what 3 numbers are stamped into the existing main jet stack.

Thanks for the reply. Looked at all the evidence and most forims are towing towards the bgm regarding build quality and performance. Yes there is 2cm extra but I don't think I will be scaping my knees any time soon lol. Don't know the size of main jet , I will have a look tomorrow. The carb is a 20/20

I haven't heard of SIP road 2's having build quality issues. Now if we want to talk fitment issues, then yes SIP Road 2 has room for improvement. On my Road 2 I had to bend both hanger tabs some to get the angle correct so the exhaust would line up to the stub, and grind the opening bigger on one of the tabs. Annoying but almost every aftermarket part I have ever bought has needed tweaking. FYI SIP Road 3 has come out, however I do not have an opinion on it yet.

I will say ground clearance for turns is not a big deal for me, however having enough ground clearance to roll my scooter on and off curbs is huge. But I am on 8", so I am already at a disadvantage.

As to performance, I don't recall there being a huge difference between SIP Road 2 and BGM BB touring. Check out this SLUK article from a few years ago comparing big box exhaust. Take it for what you will. Almost anything will be better than your (presumably) coked up vintage exhaust.

Sound: One thing I did not think about was sound when I was buying an exhaust. FMP compared 15 different exhaust sounds, you might want to take a listen.

Jetting: Did you upjet already for your new top end?

Hi thanks for your reply. When my vespa went in for the 12v upgrade it was given a new main jet. Don't know the size I will have to check this out. The guy from the scooter shop did say it would run better and advised me to change the exhaust which seemed the sensible thing to do. The scooter seems to me to be running as if the choke is slightly out until it gets warmed up. Until I get my new exhaust I don't know

On the subject of box exhausts, here's my personal experience:

1. SipRoad: Owned a pair of SIP Road 2's for the P200.
Pros: quick, revved out to over 9K
Cons: the inner wall on both of them came loose and started rattling around. Also: annoying, tinny sound. Also: minorly annoying little flat spot around 5K RPM

2. BGM: Owned two different BGM box exhausts
Pros: The BBSport was especially quick
Cons: thin metal, cracks appeared over time, swingarm mounts were hilariously under-welded and fell off

3. Owned two different Polini boxes
Pros: Rugged construction, nice muffled bass engine note, tractor-like power curve
Cons: Doesn't rev out much past 8K; also, despite the good ground clearance, the dangling exhaust pipe catches on curbs and gets hammered closed over time. Also, needs exhaust spring hooks welded on

For my money, the Polinibox is still the best allrounder for regular people right now.

One word in box exhausts... Megadella


Just joking... the polini is probably the best recommendation...

Had a BB Sport (I thought it was the Touring model until I looked at pics, duh) and SIP Road II on two nearly identical Polini 177 engines.

They're both good pipes. The BB is throatier and has a distinct mid throttle kick in. The Road is smoother and a little quieter.

Both have held up well. No issues with welds or flaky paint on either one.

I had an SIP Road 2.0 on my P200 and the insides fell apart after 2 years. I went with a Polini box exhaust and I love it.

Thanks for all your inputs. Any ideas on jetting or a bigger carb

Freakmoped on FB did a comprehensive test on the big box exhausts including Dyno, measurements of all clearances, and weld quality analysis

Yeah that sold me on the Polini. Still waiting for it after two weeks. Could be on the Suez Canal...?Haha
Three things about the Road 2 (Sport):
Can't change a tire without removing it.
Spring rubs against it. Sounds like parking a pirate ship.
It's too loud.
Maybe the Road 3 improves on these?

Bought the big box. Couldn't be happier, arrived in good time from Vespajets.com. Tony was great help , will be in touch soon. The scooter just keeps going , the torque is superb just keeps pulling up hills, just need to sort my carb out now 😀

Replaced the SIP Road 2 Sport with the Polini.
I can change a tire without removing it.
Kickstand spring rubs against it even more. Kickstand stop rubs against it too.
It's as loud.
Nice breathy feel. Slight improvement in pull, but not a $140 improvement.

Exhaust going very well massive improvement. Now I am purchasing a delorto/spaco 24/24 carburetor. Does anyone know what size keys I need. I have a pinasco 177cc kit, BGM BIG BOX TOURING and the 12v vespatronic ignition.

The Polinibox really starts showing its value 20,000km later, when its innards don't come apart, and the swingarm mounting flange stays put. Year or two ago I saw one that had made its way overland from Australia to the Balkans, and it was totally fine, despite its underside having been bashed to hell. It's a solid, reasonable, well priced box.

First, you need to upjet before you seize that thing! Which is it? A Sprint is a 10" bike and VBB an 8" bike. On an 8" bike it makes a big difference on pavement grinding your muffler too easily as you get more power and use it in the curves and turns. I can't speak to the BGM, but I had to twice modify my SIP Road to eliminate this problem by pulling the muff up as tight to the frame as possible. More here: Scruffy AllState, crappy headlight finally fixed!


fixed on the left side by redrilling mounting hole



and on the right by sectioning header pipe 3/4" and tilting it slightly