07-18-2017, 11:37 PM
ok doug,
i should be sleeping but this is a fun thread.
here's the general mcculloch specs bore and stroke
Model - Bore Stroke Displacement
MC2 - 2.165 x 1.635 = 6.05
MC5 - 2.125 x 1.375 = 4.9
MC6 - 2.125 x 1.500 = 5.3
MC7 - 2.165 x 1.635 = 6.05
MC8 & 9 - 2.165 x 1.635 = 6.05
MC10 - 2.125 x 1.500 = 5.3
MC20 - 2.125 x 1.635 = 5.8
MC30 - 2.165 x 1.635 = 6.05
MC40 & 45 - 2.165 x 1.635 = 6.05
MC70 - 2.217 x 1.835 = 7.08
MC75 - 2.250 x 1.835 = 7.29
MC49 - 2.125 x 1.375 = 4.9
MC90,91,2,3 - 2.165 x 1.635 = 6.05
MC100 - 2.250 x 1.835 = 7.29
MC101 - 2.280 x 1.835 = 7.5
ok so technically you have a bigger motor than a mc91 if you only take bore and stroke into account.
but there is something else to consider and your motor experience will help.
you have a motor with only six intake ports.
that seems pretty good till you consider all mc91's 92 92 and mc101's have eight ports.
the two extra ports provide a huge advantage in performance.
if you want to be almost competative ask to enter into the mc91 100 cc rear class.
you'll still be a slight fuel flow disadvantage but the longer stroke will even things out a bit.
or you can run in historic un-scored where you'll have a huge advantage with your engine supposedly but your wt. will drag that down a bit.
of course there are some clowns me included that run modified 9 ported motors in that class. totally legal but a bit unfair to the other guys.
my mc10 that i blew up was fast enough to run with the mc91's but it lost alot of historics with carb issues mis-adjusted clutches blown chains bad gearing.
i still had alot of fun running it regardless of results.
point is unless you intend to get into the racing end of things gear tuning is part of the learning process.
so bring what ya got. if you need a different number gear tooth find me in the pits i'll lend ya wghat ever i got in the box.
jeff,
i'm running on less than enough sleep lately and got backwards on the adjustments.
probably why i lose a few races here and there too.
wish i was drinking too much redds then i'd have an excuse.
anyway just trying to see an answer from you and i got it
sort of
i guess.
i should be sleeping but this is a fun thread.
here's the general mcculloch specs bore and stroke
Model - Bore Stroke Displacement
MC2 - 2.165 x 1.635 = 6.05
MC5 - 2.125 x 1.375 = 4.9
MC6 - 2.125 x 1.500 = 5.3
MC7 - 2.165 x 1.635 = 6.05
MC8 & 9 - 2.165 x 1.635 = 6.05
MC10 - 2.125 x 1.500 = 5.3
MC20 - 2.125 x 1.635 = 5.8
MC30 - 2.165 x 1.635 = 6.05
MC40 & 45 - 2.165 x 1.635 = 6.05
MC70 - 2.217 x 1.835 = 7.08
MC75 - 2.250 x 1.835 = 7.29
MC49 - 2.125 x 1.375 = 4.9
MC90,91,2,3 - 2.165 x 1.635 = 6.05
MC100 - 2.250 x 1.835 = 7.29
MC101 - 2.280 x 1.835 = 7.5
ok so technically you have a bigger motor than a mc91 if you only take bore and stroke into account.
but there is something else to consider and your motor experience will help.
you have a motor with only six intake ports.
that seems pretty good till you consider all mc91's 92 92 and mc101's have eight ports.
the two extra ports provide a huge advantage in performance.
if you want to be almost competative ask to enter into the mc91 100 cc rear class.
you'll still be a slight fuel flow disadvantage but the longer stroke will even things out a bit.
or you can run in historic un-scored where you'll have a huge advantage with your engine supposedly but your wt. will drag that down a bit.
of course there are some clowns me included that run modified 9 ported motors in that class. totally legal but a bit unfair to the other guys.
my mc10 that i blew up was fast enough to run with the mc91's but it lost alot of historics with carb issues mis-adjusted clutches blown chains bad gearing.
i still had alot of fun running it regardless of results.
point is unless you intend to get into the racing end of things gear tuning is part of the learning process.
so bring what ya got. if you need a different number gear tooth find me in the pits i'll lend ya wghat ever i got in the box.
jeff,
i'm running on less than enough sleep lately and got backwards on the adjustments.
probably why i lose a few races here and there too.
wish i was drinking too much redds then i'd have an excuse.
anyway just trying to see an answer from you and i got it
sort of
i guess.
Dave L.