Exhausts: SIP Road XL versus Sito Plus
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Hooked
1974 200 Rally, 1970 180 Rally, 1980 P150X and P200E
Joined: 22 May 2017
Posts: 167
Location: George, South Africa
Sun May 26, 2019 1:23 am quote
I have just replaced the Sito Plus racing exhaust on my Malossi 166 with a SIP Road XL racing exhaust, and this is my observations so far: The SIP XL is much quieter and has a very nice sound to it, sounds more like a Vespa should sound. The Sito Plus has quite a tinny sound to it and is very noisy. But the Sito Plus gives a better performance and top speed. With the Sito Plus I got up to 105 km/h (65 mph), but with the SIP XL I only got 96 km/h (60 mph), a difference of nearly 10 km/h. (The exhaust outlet of the SITO is also much bigger in diameter than the SIP; and I think it shows in the performance).

However, the SIP XL sounds good and gives a smooth acceleration, thus I will stick with the SIP. And 60 mph is more than enough!!
Molto Verboso
One or two fun scoots....nothing too precious
Joined: 17 Jul 2013
Posts: 1071
Location: UK (South East)
Sun May 26, 2019 1:39 am quote
The XL is one step away from a proper expansion chamber, while the Sito Plus is an old school 'sports' exhaust. The XL is therefore suited to higher levels of tune and will need higher revs to get the real benefits. As with many expansions, you'll miss out on the low RPM pull if the setup is too mild, and if you're not making the revs, you'll not see the top end. Your Malossi 166 is a good start, but probably needs to be tweaked for the XL, such as raised transfer duration, bigger and better shaped exhaust port, crankcase work, cut crank, bigger carb etc. Your gearing will also be a factor.

When I bought one of my PX150 scoots, it had a Scorpion expansion installed and it was rubbish. I replaced it with a NOS standard pipe and it was much better. A SIP Road 2 then improved things further. Once I'd gone down the route of cylinder kit, bigger carb and porting, I installed the Scorpion again and started to realise the benefits.
Enthusiast
PX125E
Joined: 06 Oct 2018
Posts: 92
Location: Gravesend, Kent, UK
Sun May 26, 2019 5:13 am quote
Hello. Have you checked the jetting? Even changing like for like I would always check it. I have a weird experience of swapping a SIP road 2 with an XL on my mildly tuned 125. And found the XL to be better. I even wrote a post about it last week. But I may have a duff road 2 and any other exhaust is an improvement.

Iím not as experienced and a lot of the posters on here but iím Trying to learn as much as possible.
Hooked
1974 200 Rally, 1970 180 Rally, 1980 P150X and P200E
Joined: 22 May 2017
Posts: 167
Location: George, South Africa
Sun May 26, 2019 10:24 am quote
When I fitted the Malossi, I did machine the crank to increase the transfer duration and I also fitted a 24.24 carb. I also installed a racing clutch and changed the primary drive gear with the one supplied in the Malossi kit.

But don't get me wrong, I am not complaining. I am more than happy with the speed and with the much quieter exhaust.
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