Kentucky predator bmx build

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Imthegrt1

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Nov 8, 2014
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Well this is first attempt at a build.
Like to start out by saying. I'm no pro and want all your input good or bad.
Second thing I'm not the best welder either and tend to do things different than others.
And third thing I'm no kid so my boys will do the test riding on this bike when done to insure dad don't get hurt lol.
So my builds will be based around HF predator motors and bmx 20 bikes.
We have over 59 bikes so I'm sure I will get it right sooner or later.
This first build will be 79 cc motor and a late 90's mongoose frame.
 
Ludwig II

Ludwig II

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Jul 17, 2012
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I'm a new boy at this game, and I've found a lot of creative looking, followed by measuring at least twice before you do anything, works fairly well.
 
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HotRodRob

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Apr 14, 2013
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Western KY
Sounds cool, I love 20" bikes. I have a couple right now with 66cc china girls. The predator 79cc is one of the 4 strokes Ive been keeping my eye on. Good motors from what I hear. There have been several people use the 79cc or 99cc Preddies.
What part of ky are yall from? Sounds like youve built some before. We would love to see pics of some of your past builds and some of the stuff you plan to use on this build. Can't wait to see what you've got goin on.
Rob,
 
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Imthegrt1

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We live in vinegrove ky next to Fort Knox from Louisville tho.
Trying to post pictures but it keeps failing for some reason.
 
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curtisfox

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Dec 29, 2008
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Have to get a few post in before you can post pictures. search on top for how to post pictures?....................Curt
 
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Imthegrt1

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So here were this project begins.
Motor was on sell 99 bucks than had 25 percent off so 75 bucks good deal.
By the way it's taken me a week to figure how to post pictures from my phone.
I can get on Fort Knox quicker ! Lol
 

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Imthegrt1

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Nov 8, 2014
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So compare next to older style motor the predator motor will have more room I've removed the gas tank and the factory muffler.
 

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Imthegrt1

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Nov 8, 2014
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Here is the frame Ill be using. it's a mongoose I have a couple of the same bikes so I got backups if I mess up.not worried about any painting until everything done than I'll tear it back apart and powered coat the frame.
 

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HotRodRob

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Apr 14, 2013
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Western KY
Nice deal on that motor. Cool bike as well. I'll be check'n back in on this build for sure. I'm from Ptown farther west then you guys but not super far.
 
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Imthegrt1

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Ok so here is first cut.motor will be in center of bike. Reason I went with this frame is that the frame is mostly 2inch tubing.
 

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Imthegrt1

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Here is the mock up I'll be welding up.
Now I know the wheels will be very close to the frame I should be ok if I need to I can change tire size. I put the largest tires on so I can drop in size if needed.
 

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Ludwig II

Ludwig II

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Perhaps you can bend the top tube as well a little, just to push the wheel forward, and improve the rake and trail.
 
KCvale

KCvale

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Feb 28, 2010
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Oh my, you sure choose a tough first build.
Are you one of those guys that thinks it would be fun to put a 454 CI V-8 in a VW Bug?
It can be done, but would you really trust it to drive it around all the time?

Before you get too far into this I have 1st hand knowledge that may help you from this Pred 79cc build...



That motor looks all small and cute and cheap at $75 but break out your checkbook and tools as you will have to buy or fabricate all kinds of things to make it function as a motorized bicycle.

The first thing you need to consider is the outdrive, which is the centrifugal clutch and main gear reduction.

I went with the $320 Q-matic belt drive .



It works very well, looks good, and involves no frame mods.



You can do this for less (maybe) by making your own system mounted to the frame which bring me to you 57 20" frames...

I used a 29" bike with fat steel tubes on mine because unlike a 25# 2-stroke, that 79cc/Q-matic adds around 100# of weight to the frame before you even sit on it and you are really gonna feel that on little kids 20" bike.

I just hope you have very good frame design and welding skills and tools if you plan to make a frame that can take it's weight and torque for a bunch of kid's bikes.

Just tips and words of caution, take 'em or leave 'em.
When you get to needing tips about exhaust and making that funky throttle system motorbike friendly I documented my build in detail here.
http://kcsbikes.com/topic.asp?TOPIC_ID=639

It's sound cheap and easy to start, it's neither at the end.
 
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Imthegrt1

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Nov 8, 2014
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As always kcvale thanks for your info you do build some nice bikes I'll give to you there.
I've never stuck a 454 in a vw.
But i have stuck a 350 in a Mazda rx7
And a caddy 500 in a s-10.!!those were fun and easier than these bikes lol.
Reason I I'm doing this build is you don't see a lot of the bmx bikes done I've look there are a few but I figure it be fun.i really enjoy the smaller bikes I figure after this one I'll build one with one on back than another one motor on front try a few diffenent things.
Im a little farther on this bike than posted just getting caught up.
On the throttle I was just going do a simple hand brake throttle .
 
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Imthegrt1

New Member
Nov 8, 2014
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So new area all welded up. Added couple side plates at top for more support .
By the way this is all be doin with stick welder (old school) I know welds not pretty and yes got hot a few times. But it's not moving sledge hammer tested!!
 

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HotRodRob

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Apr 14, 2013
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Western KY
I was thinkin the same thing. Its gonna be a tight fit! Looks good so far. My two 20" builds with 66cc china girls where a really tight fit and more difficult than a 26" build. I could only imagine stuffin a 79cc 4 stroker in one of my frames. Would need custom welding like you're doing for sure.

I'm kinda a short guy so my two 20" bikes fit me a lot better than my 26" did. I think you will like the smaller frame. They feel more like a moped or small motorcycle then a super tall, higher center of gravity 26" build IMO. Plus that thing is gonna have tons of power. Gonna be a wheely poppin mochine! 20" builds FTW! Keep the pics and info comin.
 
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