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Old 03-18-2014, 08:34 AM
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Default BIG CC engines on a kart

to my attempt at a tutorial on big cc engines on kart. First off, there are different types of karts. Simple yard karts, semi off road karts, pure off road karts, race karts, just to name a few. They are purpose built machines, designed to operate within certain parameters. Only so much external force being exerted on the kart, from typical "normal" use. And then there are mini buggy's.
These karts are designed to use a certain HP engine. The engineers forethought allow us to swap a 3.5hp engine for a 6.5hp on a yard kart, but you're not gonna slap a 18 hp engine on it and not have frame issues. Before I go any further, it's NOT the HP but the TORQUE of a motor that will make the biggest difference. The torque from a 6.5hp won't rip a yard kart frame apart. But if you put a 600cc crotch rocket engine on a yard kart, the frame will only last so long before you start to see cracks. You like to spin tires till they smoke? That's torque doing the work.....
Most karts are made with 1" x. 063" tubing. The bigger purpose built off road karts are made with 1.25" x .063" tube. Then there are the mini buggies with 1.25"x.093-.100" tube. The buggies use a larger cc engine so the frame material used is gonna be bigger/thicker.
Done lost track of my thoughts. anyway, if you want more speed, try gearing. If 30-45 mph isn't fast enough, step up to a 125-250cc dirtbike engine. You will have more than enough power to hit a 100mph (don't do it on a yard kart!!!!) . Even at this size engine, you run the risk of frame cracking / bending due to the torque being applied.... Engines of this size offer tire spinning/smoking torque in the lower gears then switches to speed , the higher in gear you go.
A lot of you think you are gonna put a 500-1000 cc engine in a yard kart and be cool to thrash it around. Absolutely WRONG..... To use any of the torque the engine has, the frame and drivetrain must be able to withstand it. Look at the Edge piranha or barracuda. They use big tube frames, lots of lateral supports, and gussets. The frames is DESIGNED to handle the power of a turbo 1300cc 'Busa engine. It will not fold in on itself, won't bend,cracks, or rip apart. It is designed for the power of the engine to be used to its fullest potential. You can hammer down on the throttle and KNOW your gonna be safe, ESPECIALLY at high speeds and tight turns. A lot of ENGINEERING went into them things to make them the beasts that they are.
To use these engines, you need to use your brain (or borrow one) and come up with a safe frame design. Copy a manufactured model. Just DONT slap a big ^$$ engine on a yard kart and hit the streets. It's NOT safe or smart.....
I'm done rambling..... Some one else take over..... (Doug, Tony??)

Don't get me wrong, I've put 80cc and 125cc engines on simple yard karts and had a blast. And a bigger engine does equal MORE fun,.... BUT let's be realistic about it. Are you gonna stuff a twin turbo LS7 in a Chevy colt (small car) ? NO because it will just destroy the car and it's drive train....

Ok now I'm done.....
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Old 03-18-2014, 09:02 AM
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UMMM maybe not from the torque but believe me I have broken my Piranha frame many times mostly due to thinking I can fly.
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Old 03-18-2014, 10:50 AM
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LOL If your model didn't come with wings, then no, it can't fly.... LoL
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Old 03-18-2014, 10:55 AM
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Quote:
Originally Posted by Felineman View Post
UMMM maybe not from the torque but believe me I have broken my Piranha frame many times mostly due to thinking I can fly.
That is from doing something that the buggy is not designed for though, just like putting a big engine on a little kart
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Old 03-18-2014, 12:21 PM
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Christopher Gardner: Hey. Don't ever let somebody tell you... You can't do something. Not even me. All right?

Christopher: All right.

Christopher Gardner: You got a dream... You gotta protect it. People can't do somethin' themselves, they wanna tell you you can't do it. If you want somethin', go get it. Period.


I think this is more of a problem with understanding the problems to overcome rather than not doing it. Even 3 hp go karts are dangerous. Its fun, and a good project to undertake if you are doing it for thrills and you educate yourself enough.

Sure there are a lot of threads out there with people wanting to put a big engine on a kart, but there are also a lot of threads out there with people wanting to build a simple yard kart...

What I guess might happen with those people with the great ideas, is that most of them don't end up building a simple kart, and most of them don't end up finishing their monster kart. They are at least dreaming, and can get some valid information from someone who knows how to do it, or has done it before. The problem is that it takes time and lots of forethought to build a kart, and it takes time and lots of forethought to build a monster engine kart.

I don't know if I have a strong enough opinion on it one way or another as far as monster engine karts go, but there has to be some information out there from someone who has successfully done it and would like to share that information.
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Old 03-18-2014, 01:13 PM
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There is nothing wrong with using a big engine, just as long as you have the knowhow and skills to do it
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Old 03-18-2014, 01:26 PM
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Quote:
Originally Posted by landuse View Post
There is nothing wrong with using a big engine, just as long as you have the knowhow and skills to do it
That's the big thing. If you have to ask how to build the kart then you have no business building some thing so powerful.

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Old 03-18-2014, 01:27 PM
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Don't get me wrong, I LOVE big cc karts, when built properly (or just safely)..... I'm going to use a 200-500cc quad/bike engine in my next project kart, but it will be a heavy kart with a frame made from 1.5x3" steel tube or 1.25x.09" round tube, and lots of it. Kart will be tipping the scales close to 350-375lbs (guesstimate on steel weight per foot) . I'm shooting for smoking the tires and maybe pull off a wheelie..... When you see my next build, you will know why......
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Old 03-18-2014, 07:04 PM
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Haha this should be a must read first prior to posting thread !
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Old 03-18-2014, 07:36 PM
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That sounds like a sticky vote to me; anyone else agree?
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Old 03-18-2014, 11:20 PM
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Agree
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Old 03-18-2014, 11:58 PM
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Quote:
Originally Posted by Fabroman View Post
That sounds like a sticky vote to me; anyone else agree?
Sounds good. I will give you the honour of doing it.....
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Old 03-19-2014, 04:47 AM
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ha dont worry even the busas have issues with torque

ripping a arm mounts out from the torque though the cvs

good sum up
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Old 03-19-2014, 08:03 AM
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Well, I have a couple ideas to expand the info here. Gathering said info now. I just want to make sure new guys don't get in over their head and get hurt/mamed/killed over a go kart. Karting is supposed to be good clean SAFE fun. That begins with a good frame/chassis. Knowing what materials are able to endure will be helpful in deciding what to use,get an approximate weight before the build, and that will help decide what brakes are needed.
To be continued......
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Old 03-19-2014, 04:57 PM
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Quote:
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Sounds good. I will give you the honour of doing it.....
Thanks Paul
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Old 03-24-2014, 08:29 PM
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ok , lets talk horse power for a minute. I will use this data, pulled from dirtrider magazine. The KTM 250SX two-stroke peaks out at 49.77 horsepower (at 8500 rpm). The KTM 250SXF four-stroke makes 42.88 horsepower (at 13,500 rpm). The KTM 125SX two-stroke makes 34.66 horsepower (at 11,200 rpm).
Lets keep in mind that these are dirt bikes, NOT the bigger CC street bikes every one keeps asking about. Did you see those ratings? WoW! Thats a lot of power.
Now, lets use a single seat YerfDog (any model) powered by a 6HP engine with a TC as an example. You want to go faster, so you opt for a thirteen HP engine , hopped up to ,lets say 18HP. You change gear ratios to use the new found power to get a higher top speed. Thats 3x's the HP you originally had and what the kart engineers had in mind. You are seriously stressing the frame at this point. Without reinforcement, something is gonna give. These karts are made with 3/4" to 1" tubing, .063"thick....
Now a lot of new guys think its ok to use a street bike engine, 500cc, 600cc, and 1000cc engines. That 125cc 2 stroke is putting out 35 HP! That alone is able to shred a kart frame.... My cousins new CRF450R 4 stroke's back fender says the HP rating is 60HP!!!! <<<<STOCK>>>> Do you HONESTLY think you could ever REALLY be able to use and enjoy all that power ,on a yard kart? NO
This kind of power requires a stout chassis, able to withstand the rigors of "playing", AND the power the engine is putting out. We all love karting, but we all have to be safe (read SMART) about it. There is a time and place for everything, 50+ HP on a yard kart is just not smart....
More to come ....
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Old 06-08-2014, 11:41 AM
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So putting my 350 warrior motor on my yellow jacket kart is not a good idea?
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Old 06-09-2014, 04:54 AM
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So putting my 350 warrior motor on my yellow jacket kart is not a good idea?
Like we said...if you have the skills and knowhow, then you should be fine. Otherwise don't try it
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Old 06-11-2014, 02:08 AM
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Hi mate the build will be the hardest thing I know u frown upon the build I'm doing the arrow kart frame I'm gonna use is gonna look kinda like a mini speedway midget but with the motor at the back but geared down so that it can b used by the younger ones plus a acceleration limiter
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Old 06-11-2014, 03:00 AM
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Quote:
Originally Posted by nixta View Post
Hi mate the build will be the hardest thing I know u frown upon the build I'm doing the arrow kart frame I'm gonna use is gonna look kinda like a mini speedway midget but with the motor at the back but geared down so that it can b used by the younger ones plus a acceleration limiter
Gearing down = more torque = more strain on frame = messed up frame if not braced properly
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