Socal_machinist
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6 Hp engine, 12T clutch, 72T rear sprocket, 20" driving wheel This is going to be just street. Am I going to have a good takoff with the giant wheel?
is my "take off" torque going to suck on my bike?
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Nodroz
New member
That's quite a big wheel, indeed. However, I don't think torque will be a problem. I've seen worser.
I made a minibike with a pitbike wheel of 24" diameter. I went from 8.14:1 to 11.28:1 before I got any decent take off torque. A ratio of 8.14:1 was too high for me to pull away with any satisfaction. That is why I then reworked my jackshaft to give me 11.28:1.
I think that a ratio of 72/12 = 6:1 is going to be waaay to high for the size wheel that you have. Here is a pic of my bike
I think that a ratio of 72/12 = 6:1 is going to be waaay to high for the size wheel that you have. Here is a pic of my bike
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Nodroz
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Looks like I was wrong here. Sorry.
What size of engine do you have?
It is only a 3.5HP Briggs engine, and it took me a while to get the engine running properly. It is going nicely now though
Sorry, I was wrong. My wheel is not 24" in diameter. I have just measured that with a ruler, and my wheel is not that large. This is what the tyre says
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OzFab
Well-known member
Speed calculator gives a top speed of 36mph, which is high but not excessive. I would have been worried if it spat out 40+.
The fact that it's a 6.5hp on a bike (much lighter that a kart) you might be ok (but don't quote me on that, lol).
Worst case scenario, if the take off sux, get a bigger sprocket
The fact that it's a 6.5hp on a bike (much lighter that a kart) you might be ok (but don't quote me on that, lol).
Worst case scenario, if the take off sux, get a bigger sprocket
r_chez_08
Should be in the shop...
I would say go for it.
Bluethunder3320
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sounds fine to me, i had a kart with 6.5hp 6:1 ratio and 18" tires and it actually had decent torque and it was wicked fast it was over a year ago i still have a big scar on my knee....
Socal_machinist
New member
well I'm gonna give it a shot, worst case scenario I'll just add a jackshaft with a couple of gears. Hey anyone ever put a bicycle style gear shift on a mini bike? I figure I could put a 60 tooth right next to the 72 and have the chain jump like a bicycle.
tundrabeagle3
New member
how was the acceleration?
jman231994
New member
I wouldnt risk it, bicycle chain is designed to flex heaps to allow for that. Kart chain isnt. Also bike gears use a spring loaded derailleur to tension the chain.....I certainly wouldnt trust that under heavy load
lol,just yesterday i was going down a small paved hill on 7 speed schwinn beach cuiser and i was really flyin, maby 30(im 230lbs so when i start using my weight to push the pedles i can realy go!) and i shifted up so i could go faster and my derauiller had a freak out. for some reason it decided that 7th gear whas really 3rd.so after regaining my composure after almost crashing at 30mph i tried to shift up again,and being that the gear shifter was cranked to 7 i couldnt shift up,so now my 7 speed is now a 3 speed,and if i take it below 5th the chain pops off. so i definetly dont recomend useing these for high speed,high stress aplications, unless you want your knees,hand and face to look like road pizza
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Nodroz
New member
Holy sheez! That must have hurt! I hope you're okay and not too serious injuries?
lol,i didnt crash. those are jus tpicture of road rash i googled.
how ever when it down shifed a couple gears my legs started flailing around sparatically cause they where pushing so hard and then all the resistance was taken away so i think i did somtin to my knee
i have goten road rash on my knees though.
one time it was cause of this punk a** 13 yr old wanted to rub his back tire on myne and made me wipe out. he ran away before i could do anything
but in a period of 2 years i got road rash 5 times, it was time to stop riding that 20'' bmx bike.
everbody who sees my knee and the side of my leg are like "dude! that must of hurt!"
and im like nahhhh,road rash hurts less in moderation.
how ever when it down shifed a couple gears my legs started flailing around sparatically cause they where pushing so hard and then all the resistance was taken away so i think i did somtin to my knee
i have goten road rash on my knees though.
one time it was cause of this punk a** 13 yr old wanted to rub his back tire on myne and made me wipe out. he ran away before i could do anything
but in a period of 2 years i got road rash 5 times, it was time to stop riding that 20'' bmx bike.
everbody who sees my knee and the side of my leg are like "dude! that must of hurt!"
and im like nahhhh,road rash hurts less in moderation.
tundrabeagle3
New member
that guy should have worn a helmet 
r_chez_08
Should be in the shop...
Those pictures made me wince- ****! I am keeping my helmet on now!
I hate it when my bike chain skips when I am putting loads of effort in, when you suddenly get no resistance without expecting it, you feel like your going to fall!
I hate it when my bike chain skips when I am putting loads of effort in, when you suddenly get no resistance without expecting it, you feel like your going to fall!
lol,yea. or your chain breaks all togther and goes into your spokes!i broke my wrist when that happend
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