good old polini 177 timings: 167/111/28, 57mm stroke, the 0,5mm green bottom gasket = 1,1mm squish

looks like a good base for 177ccm tuning, i like that the central spark plug cnc head and that the combustion chamber shape does NOT stand into the cylinder so its easier to use top gaskets in case of longstroke and head gaskets due to setting the right timings (otherwise u have a gap between head and gasket, as the gaskets are always bigger than the bore), channels are a little bit rough and have to be redone, but ok for this price (its also useable like this) the 2 additional channel at the boost port are interesting, cooling rips below the piston roof are missing tough... ring pin doesnt seem to be in a channel, we will check that later on again when the piston is mounted.

65% exhaust port, thats 2mm wider than the polini and the shape, the upper edge is better too

Open question:
Piston assembly clearance


so the direct rival would be the bgm 177 i guess (= quattrini m1x 172 copy)
249,- vs 299,- cash

VMC177 vs BGM177, this means
;) asian italy branded vs asian germany branded ;)
without knowing the timings of the VMC yet:

+VMC: CENTRAL spark plug cylinder head (0:23) with 4 additional screws (2:39) = 8 points of fixation
+VMC: removable metal exhaust socket (1:24)
+VMC: more boost port area due to 2 additional side channels (1:57) (2:00)
+VMC: bigger transfer ports out of the box
+VMC: transferport windows in the cyl foots are bigger (1:48)

the bgm has to be opened at the transfer ports
(closing them is not needed for pnp tuning, see malossi sport 211)
the bgm cyl foot at the transfer ports is also aprox1cm higher (standing on the top)

+VMC: the gaps/cutouts in the cyl foot are nice (1:47)
as this areas always stands in the flow
(polini 207 iron cast has sthg similiar at the bosst port, but smaller)
+VMC light biconical piston pin

+BGM: piston with 2 rings

the VMC piston seems to be a bit stronger (0:59)
look at the side window embracement stronger
and perhaps also the boost port window (1:04)

nice to have
+VMC: 2 holes in cooling rips for exhaust springs (1:34)

facit:
With the VMC for 50,- bucks less
u get more as the bgm offers
In my eyes:

a central cyl head with 4 add screws
a metal exhaust socket,
bigger transferports / where u dont have to do anything
& a bigger boost port
more options of timings adjustment in case of longstroke
(= head chamber shape not inside the cylinder)

VMC 177 has timings as iron cast polini 177
167/111/28, 57mm stroke, 0,5mm green bottom gasket = 1,1mm squish

good for pnp and as well basic tuning
proper timings ie:
174/120/27, 57mm stroke, 1,5mm lifting
174/120/27, 60m stroke, 0, 5 lifting, 1mm top gasket --------------------------------------------------------------------------
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