Ok so starting my build on my bike plan it has a jackshaft if i ran 12 to a 18 on the jackshaft then a 15 sprocket to a 60 sprocket give me a 4:1 ratio im running 18.5 tires and calculated the 15 to a 60 for a 4:1 ratio would give me almost 50 mph could i change sprockets on the jackshaft to get that or would i need to replace both gears on jackshaft
Could i run this setup
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Poboy kartman
Senior Moments Member
No....just no....
when i calculate it on a jackshaft calculator i put
Engine:12
JackShaft in:18
Jackshaft out:15
Axle:60
gets me a 6 ratio how would i get it to a 4 plan on doing this with predator 212
if it helps i want to be able to do 40+ had one go kart with 12 to 72 didnt like it and another one with 12 to 60 and that was ok but my cousins old chopper could do 40 and thats what i liked
Engine:12
JackShaft in:18
Jackshaft out:15
Axle:60
gets me a 6 ratio how would i get it to a 4 plan on doing this with predator 212
if it helps i want to be able to do 40+ had one go kart with 12 to 72 didnt like it and another one with 12 to 60 and that was ok but my cousins old chopper could do 40 and thats what i liked
just because I just have that number from a different thread:
5.5: 1 on 19" wheels with a TORQUE CONVERTER (not a clutch.. would NEVER work with a cent clutch!!!!)
will give you 41mph... and is in the realms of feasible with a predator engine as long as you stay below 275lbs total weight (bike plus your butt)
'sid
PS Oh and.. just because we've just seen that stupid pubertarian killing himself on a modded mini bike..
DO NOT REPLICATE HIS RESULT!.. just sayin'
5.5: 1 on 19" wheels with a TORQUE CONVERTER (not a clutch.. would NEVER work with a cent clutch!!!!)
will give you 41mph... and is in the realms of feasible with a predator engine as long as you stay below 275lbs total weight (bike plus your butt)
'sid
PS Oh and.. just because we've just seen that stupid pubertarian killing himself on a modded mini bike..
DO NOT REPLICATE HIS RESULT!.. just sayin'
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
Your cousins 12 to A 60 was 5:1
If you eliminate your jack shaft you are also 5:1
Or just put 2 15s on the jack shaft. you will have 5:1
Or swap your jackshaft gears 12 15 18 16 this will get you 4.167:1
However the 4:1 ratio will probably just burn up your clutch.
4:1 is like driving a stick shift car and trying to take of from a stop in 4th gear.
unless you have incredible HP it aint gonna move.
---------- Post added at 05:45 PM ---------- Previous post was at 05:40 PM ----------
I just want to add. If you notice all the gears you already have. Just by moving them around you can get 4:1 5:1 or 6:1.
Since it is pretty much free, try it!
If you eliminate your jack shaft you are also 5:1
Or just put 2 15s on the jack shaft. you will have 5:1
Or swap your jackshaft gears 12 15 18 16 this will get you 4.167:1
However the 4:1 ratio will probably just burn up your clutch.
4:1 is like driving a stick shift car and trying to take of from a stop in 4th gear.
unless you have incredible HP it aint gonna move.
---------- Post added at 05:45 PM ---------- Previous post was at 05:40 PM ----------
I just want to add. If you notice all the gears you already have. Just by moving them around you can get 4:1 5:1 or 6:1.
Since it is pretty much free, try it!
Poboy kartman
Senior Moments Member
You don't need to get rid of the jackshaft...just the idiotic idea you can run a 4:1 gear ratio.
Ill go with the 5:1 but still wondering about the chain tensior if i run straight to the axle
---------- Post added at 08:31 PM ---------- Previous post was at 08:25 PM ----------
also if i got this fork i should be able to put it on my bike as long as the pipe is the correct size of course and its the same size length wise correct?
http://www.ebay.com/itm/like/281626952889?lpid=82&chn=ps&ul_noapp=true
---------- Post added at 08:31 PM ---------- Previous post was at 08:25 PM ----------
also if i got this fork i should be able to put it on my bike as long as the pipe is the correct size of course and its the same size length wise correct?
http://www.ebay.com/itm/like/281626952889?lpid=82&chn=ps&ul_noapp=true
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
One way to keep the jack shaft but eliminate the gear change is just run same tooth count gears on it. 15 and 15 or 18 and 18 or what ever. That way you jackshaft acts as a "chain tensioner " or idler gear.
Since people talked me out of the 4:1 and into the 5:1 just do 12 on the three and 60 on the axle?
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
That would work. 12 12 12 60.
https://www.affordablegokarts.com/GearCalc.php
https://www.affordablegokarts.com/GearCalc.php
If my current setup on the jackshaft is a 24 tooth and a 12 tooth on the axle side that calculates to a ratio of 10 lol i dont understand this jackshaft ratios it throws me off
cus wouldnt 12 to 60 just be 5 how does it double to 10 i understand 12x2 is 24 so thatd be double to 10 but how would that affect it could i just run the 24 and 12 and itd be the 5 im looking for?
does the 24t even matter?
cus wouldnt 12 to 60 just be 5 how does it double to 10 i understand 12x2 is 24 so thatd be double to 10 but how would that affect it could i just run the 24 and 12 and itd be the 5 im looking for?
does the 24t even matter?
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
I dunno. I just use the jackshaft calculator to get the numbers I want.
If I thought real hard and did the math myself I can figure it out.
If I thought real hard and did the math myself I can figure it out.
Okay...
easy actually:
toothcount axle sprocket divided by toothcount jackshaft OUTPUT sprocket.
(remember the value)
Jackshaft INPUT sprocket divided by clutch(TC) sprocket
(another value to remeber...)
multiply the two!
example:
(clutch -> jackshaft in - jackshaft out -> axle)
12 -> 24 - 20 -> 60
60 / 20 = 3
24 / 12 = 2
2*3 = 6
overall ratio 6:1 in this example
you want to gear higher (lower number)
increase one of the smaller values or decrease one of the larger values
you want to gear lower (bigger numbers)
do the exact opposite
'sid
easy actually:
toothcount axle sprocket divided by toothcount jackshaft OUTPUT sprocket.
(remember the value)
Jackshaft INPUT sprocket divided by clutch(TC) sprocket
(another value to remeber...)
multiply the two!
example:
(clutch -> jackshaft in - jackshaft out -> axle)
12 -> 24 - 20 -> 60
60 / 20 = 3
24 / 12 = 2
2*3 = 6
overall ratio 6:1 in this example
you want to gear higher (lower number)
increase one of the smaller values or decrease one of the larger values
you want to gear lower (bigger numbers)
do the exact opposite
'sid
chancer
ɔ ɥ ɐ u ɔ ǝ ɹ
Thanks sid
I just did not have the train of thought to express it clearly.
I just did not have the train of thought to express it clearly.
mckutzy
Well-known member
All this and no pic of the bike........
OP... can you post a pic or 2 of the bike in question?......
OP... can you post a pic or 2 of the bike in question?......
On mobile right now
https://imgur.com/iLmKLIE
Plans are to get a new plate on the bottom and I'm going to get the jackshaft kit on bmi also needs a new fork bearings suck and its crooked anyway getting it and blasted after ward not sure what I'm going to do for a tank all I see for tanks are single bar
https://imgur.com/iLmKLIE
Plans are to get a new plate on the bottom and I'm going to get the jackshaft kit on bmi also needs a new fork bearings suck and its crooked anyway getting it and blasted after ward not sure what I'm going to do for a tank all I see for tanks are single bar
mckutzy
Well-known member
Here let me help you....
It looks like the motor will accommodate if not all your motor choices.
Ya maybe go with the new jackshaft as it look like the one sprocket is welded onto it.
I think you need to figure out something with the rear brakes, but Its a doable project.....
It looks like it has a pocket bike front wheel, so im guessing the brakes off of that will do.
I have the exact same rear tire as that, and a 6:1 ratio will be plenty and scary enough in that machine.....
It looks like the motor will accommodate if not all your motor choices.
Ya maybe go with the new jackshaft as it look like the one sprocket is welded onto it.
I think you need to figure out something with the rear brakes, but Its a doable project.....
It looks like it has a pocket bike front wheel, so im guessing the brakes off of that will do.
I have the exact same rear tire as that, and a 6:1 ratio will be plenty and scary enough in that machine.....
Yep both sprockets are welded on the jackshaft plan on getting disc brakes for the rear and even though i believe you about the 6:1 i really want to try a 5:1 i gotta make it be able to beat the karts i just sold to my buddy and his shop
What this thing really needs is a new fork bearings are completely shot but im not sure what forks would work exactly maybe just look for local motorcycle parts you think?
What this thing really needs is a new fork bearings are completely shot but im not sure what forks would work exactly maybe just look for local motorcycle parts you think?
mckutzy
Well-known member
No, they all have a much bigger head tube... maybe a mountain bike... but overall you might have to make custom cups and get new bearings....
I would try it first, as the weight is about half, and if you havent rode it yet its going to be a shocker, beat you friends later, work on getting the kinks out and seeing how it rides....
I would try it first, as the weight is about half, and if you havent rode it yet its going to be a shocker, beat you friends later, work on getting the kinks out and seeing how it rides....
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