3 speed jack shaft

Dan · #71 (**permalink**) 10-13-2009, 07:46 PM

I am told it is just a matter of number of posts TN.

camlifter · #72 (**permalink**) 10-14-2009, 07:17 AM

"Suldnt U be out making big trouble ford Moose and Sqwarl?"

damn it dan, i just spewed coffee all over my computer. i may have to come to frostbite falls and pay you back

The Newbie! · #73 (**permalink**) 10-14-2009, 07:07 PM

Ok as long as we're talkin about 3spds n jackshafts, btw.....is it just me or does it ever seem to anybody else like yer bike will just never be done? Mann.....anyway back to the afore mentioned, ok my original bike (still just not quite done), "The Ratt-Turd" (that story's in a different thread) has a jackshaft, pullin on a Sturmey 3 spd, (finally figured out how to build that stupid, cool jackshaft) starts from a dead stop with NO strain on the clutch at all, revs out in 1st and 2nd n upto 25mph lickity split, goin into 3 it gains speed slowly, but never reaches those higher revs! How come?

If this helps, the sprocket on the engine is whatever comes on it (10tooth?), that 1'z pullin on a 25tooth, on the other side of the jackshaft there's a 12 tooth pullin on that Sturmey! Haven't checked The Sturmey's ratio, anybody know it off the top of their head? C'mon you guys who's the man, the men, any ladies out there, that can help me wrap my brain around this and really understand what I need to do to go in the direction I wanna go which ever way that might be!

Here's a lil evolution of the "RattTurd" from right to left! Oh n those aren't the sprockets that are currently on the bike! what ya see there is a version that didn't work for me! I'll update it soon!

camlifter · #74 (**permalink**) 10-15-2009, 07:08 AM

on your jack shaft in front of the rear wheel. you need to swap the sprockets. the larger one needs to be on the left and the smaller one on the right, keep going bigger on the left and smaller on the right untill you get what you want. the 3 speed hub ratios are -25% in first 1-1 in 2nd and +33% in 3rd. the china 2 stroke isn't going to pull 3rd very well. you may have to gear it so you get good performance from just the first two gears and not use 3rd. the way i have mine set up 3rd pulls ok on flat roads but if theres any incline at all i have to down shift to 2nd. thats where the 5 speed would shine since it has more under drive gears than the 3 speed.

tyrslider · #75 (**permalink**) 10-15-2009, 12:55 PM

Cam, what is the rpm range on the honda 35cc vs that of a pocket bikes? Having experienced some chain problems myself I'm inclined to believe that the chain in the box is likely to fail early and often. If it is the 2 strand chain maybe not. The hs 50 and Honda 50 spin up to 7000-8000 rpm, coupled w/ the small sprockets those speeds require an oil bath and still reduce the hp/load limits of the chain exponentially.

Some very nice work! Keep us posted!

camlifter · #76 (**permalink**) 10-15-2009, 01:07 PM

prety sure the max rpm on the 35cc is 7600,

more gears dosen't mean more top speed, these little engines don't have the power to pull higher gear ratios. the 36T sprocket is about all a china girl is going to pull.

more gears in the lower under drive range will get you up to speed faster, no low speed bogging or jerking, or you could just pedal and be done with it.

tyrslider · #77 (**permalink**) 10-15-2009, 03:07 PM

don't know whether you were talking to me about sprockets or not but I mean the chain speed inside your box mounted on your motor. Basically, the smaller the smallest sprocket is and the faster you spin it (beyond optimal) the lower the hp rating on a given chain.

http://www.ustsubaki.com/general_cd/...rs25-rs240.pdf

they have the strongest chain I've found!

azbill · #78 (**permalink**) 10-15-2009, 07:23 PM

their 41 chain is what came with my kit,,,
2400+miles and no noticeable stretch or anything

UncleKudzu · #79 (**permalink**) 10-17-2009, 07:07 PM

Quote:

Originally Posted by camlifter

thats where the 5 speed would shine since it has more under drive gears than the 3 speed.

hey, camlifter, which 5-speed are you looking at? that bidniss with the 2 underdrives sounds good for my human-powered, non-motorized bicycle. i was aware that second gear was usually 1:1 on a 3-speed, but didn't know about how the 5-speed worked. there's some mean hills around here; two lower gears on my favorite pedaler might be nice sometimes.

this has turned out to be a really interesting thread, BTW. i hope you'll continue to update us with the latest on your "gearbox".

camlifter · #80 (**permalink**) 10-19-2009, 07:43 AM

Sturmey Archer