99cc predator jackshaft

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dirtbikemike2435

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Aug 16, 2011
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illinois
I just recently purchased a predator and looking where to go with this build.. but i am wondering will the predator need a jackshaft kit to run chain drive?
 

MotorBicycleRacing

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Jul 28, 2010
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SoCal Baby!!!
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Not really possible because your rear sprocket would be bigger than this one
and your motor would be offset way to the right to line the chain up with the
back wheel.




That kind of set up works on mini bikes with tiny wheels.


 
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wayne z

Active Member
Dec 5, 2010
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I have seen AGK's website, i know their parts, but i am wondering if i can just run a chain straight from the clutch to the sprocket on the wheel...no jackshaft, is this possible?
Yeah, you can do that succsefully if the sprocket is slightly smaller than the tire, no matter it's diameter, and have a useable drive ratio.
Best thing is to do the research and the math . Use the gear calculator stickey in the DIY forum, and not waste money having to re-do your sprockets to get it right.
 

tigmaster

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Jul 17, 2011
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Hello DirtbikeMike2435...Can I call Ya Mike?....What Your saying is from the clutch to the rear sprocket like a dirtbike?..It can be done,just sayin' for instance You could find a rear sprocket big enough to allow a good gear ratio of any where from 10 to 1 or lower like 13 or 14 to 1... You will run into problems with a chain line that will push the engine out to the right to allow a straight shot at the rear sprocket...The use of the J/S will let You put the engine "on center" in Your frame,and let You play with chain alinement...Plus it'll be ez to flip some other gear ratios on there...What bike?Your size?Bikes intended use?...Ect..All comes into the pic figgerin' G/R....Wow,didn't mean to rattle on...Tigmaster....
 

wayne z

Active Member
Dec 5, 2010
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Personally, I like the belt drive, primary and secondary It's very quiet, and you can easily walk the belt off the secondary with no tools at all, if you want or need to pedal with no drive train resistance at all.
Here's a pic of my 2 speed version.
22.jpg
 

MotorBicycleRacing

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Jul 28, 2010
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Yeah, you can do that succsefully if the sprocket is slightly smaller than the tire, no matter it's diameter, and have a useable drive ratio.
Best thing is to do the research and the math . Use the gear calculator stickey in the DIY forum, and not waste money having to re-do your sprockets to get it right.
Here is the best ratio calculator:
http://jimsitton.net/ratiocalc/

10 tooth on the clutch
90 tooth on rear wheel

9 to 1 ratio

26" wheel at 5000 rpm = 43 mph

The 14"? wide 99 cc Predator would have to be offset to the right
and the chain would probably hit your frame.
 

the13bats

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May 3, 2012
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I was looking into the same thing,
any wheel bigger than say the ones you see on a mini bike or go kart would need a rear wheel sprocket almost as big as the wheel, which isnt normally practical,

It was over 30 years ago I knew this fellow who took a 3.5 edger engine a mini bike clutch and made a motorcycle, his buddies said it wouldn't work due to gearing,
He mounted the engine on a rack over the rear wheel, and used belt drive not chain, he had cobbled up a special rear wheel with a huge "V" pulley from an industrial wall fan,
It worked pretty well, I rode it, the thing I didn't like was the engine gave a high center of gravity feel and the thing was way too fast for an old bicycle with crappy brakes,

So I figure in most cases we are stuck using a gear deduction drive,
The one that go cart place sells seems costly for just a piece of metal with a couple gears on it, perhaps I'm just cheap.

So do we have other factory built gear drives out there to choose from ( that fit the predator 99 )
 
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Ibedayank

New Member
Oct 29, 2011
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Columbia Tennessee
I was looking into the same thing,
any wheel bigger than say the ones you see on a mini bike or go kart would need a rear wheel sprocket almost as big as the wheel, which isnt normally practical,

It was over 30 years ago I knew this fellow who took a 3.5 edger engine a mini bike clutch and made a motorcycle, his buddies said it wouldn't work due to gearing,
He mounted the engine on a rack over the rear wheel, and used belt drive not chain, he had cobbled up a special rear wheel with a huge "V" pulley from an industrial wall fan,
It worked pretty well, I rode it, the thing I didn't like was the engine gave a high center of gravity feel and the thing was way too fast for an old bicycle with crappy brakes,

So I figure in most cases we are stuck using a gear deduction drive,
The one that go cart place sells seems costly for just a piece of metal with a couple gears on it, perhaps I'm just cheap.

So do we have other factory built gear drives out there to choose from ( that fit the predator 99 )
a gear drive uses gears only not sprockets and chains or pulleys and belts. That is why its called a GEAR drive. As far as the cost of AGKs jackshaft chaindrive kit. Why don't you have your local machineshop machine you one and see how much they charge you in labor and materials. Thick aluminum plate is not cheap. But these are things a REAL builder would already know. Have a great day now ya hear!!!
 

dirtbikemike2435

New Member
Aug 16, 2011
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illinois
well ya see i forgot to mention that i would probably go rack mounted, but im a little worried for center of gravity, i suppose i could find a machinist who could make one. But im just playing the field now thinking of clever ways to make this work. I wouldn't mind the steep gear ratio, has anyone considered possibly a friction drive preddy, but then again you wouldent want the off set weight on the side of the bike.
 

the13bats

New Member
May 3, 2012
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Orlando
"I-Bed-A-Yank"
I see you really are one of those forum trolls who is obsessed with following me from post to post, how sad.
Me, I have been out in the shop working on my stuff, you have been stalking me.
I'm not here to try to impress you, Go thump your chest about how wise you ( think ) are to someone who cares.
While you try to pick a part my builds with uneducated negativity and play with semantics you need to pay more attention to your own spell check and build.
I don't give one obese rodents rectum if I called the unit a "gear drive" in the hast of a post.
My spelling/typo stated "Gear Deduction Drive"...of course that should have been "gear reduction drive"...well, Duh!
So Mr Forum Nazi,
I couldn't care less if the reduction in gearing is done with gears, sprockets, belts, chains, pulleys,
As far as what machine shops would charge I wouldn't know I would walk out to my shop and coddle one up for free, ( What a REAL builder does ) Now please get over your obsession, stop beating the dead horse and let it go, I kindly ask you not to follow me to each thread I post in and spew your asinine remarks directed at me.

DirtBikeMike,
Forgive my high jack of your thread with my rant, I had a Gnat in my ear.

I have not personally played with the predator 99 yet, I did putz with one at HTF but was in a hurry, when I can get back over I plan to pick one up.
Any word if they fixed the shaft size issues?
I have seen many people use this engine on bikes, I wouldn't want anything high mounted, however the Predator isn't as heavy as that old 3.5 edger engine bike I rode, it was something that one could get used to, the brakes are what needed the most attention.
So I do not without more thought believe that rack mount would be a bad thing with the Predator,
Friction mount might as you believe get a bit hairy, I never even cared for the feel of a small friction mount, my first was a Taz on the front wheel....yuck!
 
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BarelyAWake

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Jul 21, 2009
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cannonball2

Well-Known Member
Oct 28, 2010
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Colonial Coast USA.
There are several members here that have built Preddy FDs. Just search. I have been riding a Lifan(similar weight) FD for about a year now and find the offset weight not an issue and in fact, not noticable in any major way. If FD is a method of drive you want to try, these engines work well. One advantage is you can easily build a full suspension bike.