mp3 400 with upgraded 94mm cylinder
Post Reply    Forum -> MP3 Discussion
Author Message
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 619
Location: tampa
Sat Jan 04, 2020 8:51 am quote
looking for info on swapping in the 94mm cylinder from the 492.7 twin spark motor. the 400 and 460cc engines have 69mm stroke. the 492.7 has 71mm stroke. so would like to find whats needed to use the larger bore cylinder. 1mm extra gaskets under cylinder? is there a way to compensate for cam gear timing? gear would change timing a tad with cylinder swap. is it a concern?

400 85.5 x 69
460 92 x 69
493 94 x 71

scooter center says it just swaps in. cylinder of 94mm slightly shorter and works fine on the shorter stroke motors

1mm seems pretty significant to me. not using extra 1mm would mean compression would be lowered by not using gasket. but maybe that is a good thing since the piston is higher compression as well..
Gilera Fuoco 500ie
Joined: 11 Oct 2009
Posts: 4202
Location: Netherlands Olst
Sat Jan 04, 2020 8:47 pm quote
nope cylinder will fit without problems the pstion needs some work
Cross Egypt Challenge - A 2400km ride throughout Egypt   Vespa Wasp Pin Badges   Yelcome Leather Top Cases and Roll Bags for Piaggio Vespa PX LX LXV GTS GTV
Post Reply    Forum -> MP3 Discussion
[ Time: 0.1102s ][ Queries: 25 (0.0245s) ][ Debug on ]