top speed for 8.4:1 gear ratio

nate_lohs · Post by **nate_lohs** » Tue Oct 16, 2007 10:56 pm

anyone happen to know what the top speed is for 8.4:1 gear ratio? im just wondering if im anywhere near close to what i should be at.

tru72 · Post by **tru72** » Tue Oct 23, 2007 6:48 pm

my bike with 8.5 wil do 68/70 mph, but that with a mini stroker, 72cc polini..
So whats your top speed now? if its restricted im guessing about 35. Gears wil definatly help you out in the top end, but the bottom" of the line" will get slower. Also another thing is if you place has alot of hills, the more gears wil make it harder to climb them.
aloha
D

MySpree · Post by **MySpree** » Tue Oct 23, 2007 8:43 pm

abotu 45-50 unrersttricted.

nate_lohs · Post by **nate_lohs** » Tue Oct 23, 2007 9:02 pm

well i know my top speed is no where near 68. i have the stock speedo and the needle goes to the all the way to the right. sometimes it will just about disappear. heres my setup

dio with 72cc cmr bore
8.4:1 gears
premix 50:1 with oil pump removed and hole plugged.
stock carb with uni filter and #100 jet
r1 exhuast pipe

anyone happen to know what speed i would be at if the needle was at the far end of the speedo?
im in the process of trying to hook up this bicycle speedo to my scooter so i can get a better idea of my speed. also would down jetting a little and running my stock air box decrease my speed any? if it sounds like my top speed is too low what could i start to check to see whats causing me to be slow? thanks

tru72 · Post by **tru72** » Wed Oct 24, 2007 6:01 am

they way I check is 2 ways, i use a gps and when possible i used a radar gun
my bikes speedo is about 5 to 7 mph fast. I just did some testing tonight with my new 72 polini ported, did 65 then backed off because it felt lean. this new motor should get me into the 70's pretty easily. i hope!
have fun! and happy tuning!
aloha
D

stillspeeding · Post by **stillspeeding** » Thu Oct 25, 2007 2:38 am

Dump that 12mm carb and go with an 18 or 28mm carb with intake and you may see 64mph? you could also go with a dio rear pulley, grind the high spots off the case to clear the belt, mine are all strokers so i can estimate 68mph depending on the pipe.