Comparing the VTS 200 and the 250i Parts Catalogue I could not find anything that look like a device that could improve performance on the bike. Interesting, where do they get the idea that it would improve performance.
So today, armed with my faithful Samsung Camera phone I decide to do a snoop on an installation in progress.
Okay what they meant by "vacuum" is this "Breather Chamber Assembly" Part Number : 1738A-HMB-00 as photo below.
It is actually a device that installed to those SYM to meet euro emission 4 standard, on the VTS 200 this device is not installed. What it does is to recycle vapour from cylinder head area back into the carburettor for combustion. If its not installed,as on VTS 200 those vapour from this area is simply vented out to ambient, and that not meeting the euro spec. BTW being non EFI is already don't meet Euro Spec 4 for these SYM VTS 200.
Above photo of this "vacuum" unit and where the connection goes to. These device is there all the time on cars and bike that needed to pass the European Regulation. How does it make your bike run smoother or increase power ? More about that later... :)
Below shown "Vacuum" installed on 250i, the VTS 200 is similar with slight difference on the Cylinder head tapping point.
Cylinder Head tapping point as shown below for the VTS 200.
Below overly simplified schematic of the installation, point to note is that SYM VTS 200 Engine Case vent already fitted with similar unit which is bigger and its feeding the carburettor intake to burn off excess vapour from engine case as shown in next photo..
Engine Crank Case venting breather
After installing this "vacuum" the mechanic need to readjust the fuel air mix at the carburettor to compensate for additional air flowing into the carburettor by fiddling the screw in diagram below.Q1. What does this "vacuum" do to the bike ?
A1. What it does is only to make the bike run "Greener" for the Euro Emission Specification.
Q2. Will it increase POWER ?
A2. Answer : Yes (Psychologically)
Q3. Will it make the bike run smoother ?
A3. Answer : See A2
Conclusion : Unless you want to go green, then its no point of installing this item.