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Old 12-22-2008, 06:48 AM
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Default 2.5HP Go Kart Build

Hey guys ive decided i want to build a go kart. I was going to build a minibike but ive already got 2 bikes so i probably wont use it enough. I have a 2.5hp briggs and stratton engine, do you reckon this will be enough to push me at around 50km/h-60km/h? Ive seen a video on youtube of a guy with a 2.5hp engine on his kart and it goes around 45km/h i reckon and hes a big guy. Im only a young kid and weigh 50kg so it should hit 50km/h. Here's the video im basing my speed on:

Ive also made my frame out of foam as a tester to check for sizing and stuff. Heres the vid to the foam frame:

Does this look alright? Im going to go with the racing kart design and have the motor next to me instead of behind me. Im also going to widen the frame by 10cm so the motor will be a bit further away from me and the seat centred in the frame. The frame is 95cm wide and 125cm long. The tubing around the kart is going to be 3cm or 4cm square tubing except for the motor mount bars, they will be 5cm by 3cm tubing. The reason for having the motor next to me is to save on more weight. If i have it behind me its going to be a bit heavier and with the motor i have i want it as light as possible.

Ive also designed the frame to have room for a bigger motor. Its capable of having up to about a 5hp in there, it just means the motor will be closer to me and i might have to re drill mounting holes. I want it to be one wheel drive but if its cheaper for live axle i will do that.

Well thats my idea so far, your more knowledgeable on this stuff than i am so can you guys tell me if this will be good/bad and what i need to change.

Thanks,
From Brendon.v
  #2  
Old 12-22-2008, 08:43 AM
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Look's alright. Except I wouldnt build it out of foam first. Just make a desihn and build with steel then. The last time I bought foam it was like $15 for 4" thick x 12" x 12"
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Old 12-22-2008, 10:08 AM
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if it was me, i would mount the motor directly behind the seat. up to you tho. imagine riding around and accidently rubbing the hot motor...
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Old 12-22-2008, 11:04 AM
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Quote:
Originally Posted by jr dragster Tyler View Post
Look's alright. Except I wouldnt build it out of foam first. Just make a desihn and build with steel then. The last time I bought foam it was like $15 for 4" thick x 12" x 12"
Reading comprehension. He already did.
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Old 12-22-2008, 11:11 AM
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Quote:
Originally Posted by brendonv View Post
Hey guys ive decided i want to build a go kart. I was going to build a minibike but ive already got 2 bikes so i probably wont use it enough. I have a 2.5hp briggs and stratton engine, do you reckon this will be enough to push me at around 50km/h-60km/h? Ive seen a video on youtube of a guy with a 2.5hp engine on his kart and it goes around 45km/h i reckon and hes a big guy. Im only a young kid and weigh 50kg so it should hit 50km/h. Here's the video im basing my speed on:

Ive also made my frame out of foam as a tester to check for sizing and stuff. Heres the vid to the foam frame:

Does this look alright? Im going to go with the racing kart design and have the motor next to me instead of behind me. Im also going to widen the frame by 10cm so the motor will be a bit further away from me and the seat centred in the frame. The frame is 95cm wide and 125cm long. The tubing around the kart is going to be 3cm or 4cm square tubing except for the motor mount bars, they will be 5cm by 3cm tubing. The reason for having the motor next to me is to save on more weight. If i have it behind me its going to be a bit heavier and with the motor i have i want it as light as possible.

Ive also designed the frame to have room for a bigger motor. Its capable of having up to about a 5hp in there, it just means the motor will be closer to me and i might have to re drill mounting holes. I want it to be one wheel drive but if its cheaper for live axle i will do that.

Well thats my idea so far, your more knowledgeable on this stuff than i am so can you guys tell me if this will be good/bad and what i need to change.

Thanks,
From Brendon.v
I'd be worried about weight distribution. All the weight would be at the back

But otherwise, I likey Oh and hey buddy
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  #6  
Old 12-22-2008, 12:45 PM
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i cant really see how they got that much oomf out of a 2.5 hp but watevr.

I know nothing!
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Old 12-22-2008, 05:54 PM
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I got the foam for free, i can get 10m by 10m of it any size for free if i wanted too. My dads friend makes transportables and they have a massive factory full of massive sheets of foam every thickness.

With the motor heat, i am widening my frame by 10cm so i will be a bit away from it, i might also put a thin sheet of balsa between me and the motor so it protects me from accidentally touching it.

Yes i am also amazed how he got that power out of that 2.5hp, well no one really does it so ill try it out. Ill be the tester for small motors, if it works then other people can use 2.5hp. XD

I cant start building my frame for another week since i need the welder and its at my dads factory and hes on Christmas holidays for a while. So i got time to change my design and hunt down all the parts, then all i have to do is go there and weld it all together. Whats the smallest thickness of square tubing i can use and it will still be strong? I want it to weigh the least it can so anything to minimize weight would be good. Im looking into other metals other than steel so its lighter. Ill see how much aluminium square tubing is or if my dad has some, then ill ask one of my dads mates whos a welder to see if he can weld it up for me for a couple of bucks. If its to expensive though then ill go with steel but alu is like 1/2 the weight!

I shall keep you guys updated.

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Old 12-22-2008, 06:10 PM
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i wouldnt go with aluminum tubing for the frame. it bends easily and isnt strong. go with steel for the main frame and then use aluminum where you can because you will need good support on your frame.
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Old 12-22-2008, 08:56 PM
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Use steel for the frame.

Quote:
i might also put a thin sheet of balsa between me and the motor so it protects me from accidentally touching it
Good idea, but I would use aluminium or steel sheet. Balsa is pretty weak, and could catch fire if it is near the exhaust.
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Old 12-22-2008, 09:09 PM
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Quote:
Originally Posted by modelengineer View Post
Use steel for the frame.


Good idea, but I would use aluminium or steel sheet. Balsa is pretty weak, and could catch fire if it is near the exhaust.

i wouldnt use a metal if it will be near the exhaust, for the sheet of metal will get pretty warm and make for a semi-uncomfortable ride... try putting the aluminum/steel by the motor and the balsa by you! the best of both worlds lol
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  #11  
Old 12-22-2008, 09:16 PM
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Considering the recoil side of the motor is facing him, there really isn't much to worry about. Racers have the exhaust and clutch right next to them, and they don't complain.
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Old 12-22-2008, 09:50 PM
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I would just make the whole kart less wide and put the motor behind the seat. The loose of width should make up for the extra weight and your weight distribution would likely be better.
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  #13  
Old 12-23-2008, 01:49 AM
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I got my 10" wheels today! They where in the go kart shop and my dad said he can get em cheaper from another shop as he runs it through the business. We got them for 30 each (usually 45) and the best thing is, i didnt pay for them. My dad did, what a nice dad! Well thats 120 bucks i get to keep.

Im not going to put the motor behind me unless a bigger motor wont fit in there later on. Could someone do me a massive favor and measure the width of there 5hp-7hp engine so i can build the frame to cater for a bigger engine. If it just wont fit ill add on an extra bit on the end of the frame for the motor. I cant really make my frame skinnier or it wont be wide enough and roll over easier. Some people are saying having the engine at the back will make it about the same weight as having it on the side. That isnt really true. The frame atm is 85cm wide and 130cm long. I cant really make it much skinner or it will tip easy. I can only take off about 5cm which equals around 1kg or less of metal. Making the back bit would be way over that.

I should get my clutch soon, i think im going to have to order my sprocket from the internet and the rest i can get easy or make. Im going to mount my sprocket on the left wheel and im going to mount a made up brake disc on the right wheel and have the caliper on that.

I shall keep you guys updated.
From Brendon.v
  #14  
Old 12-23-2008, 05:34 AM
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Ok ive been talking with many people and they all say mount it behind and ive decided thats the way to go. So, my gate out the back of my house has an 85cm gap, i need to get my kart in there so it needs to be 85cm wide in total including wheels n all. The wheels are about 10cm wide and all the turning stuff will take up around 5cm each side so 20cm+10cm=30cm 85cm-30cm=55cm

So if i make the frame 50cm wide to be sure it will fit that makes the total width of the kart about 80cm which should make me stick to the ground good enough. I also need to add on the bit at the back so if i add on an extra 40cm that will allow me enough room to add on up to around a 8hp later on. So the new dimensions are 50cm wide by 170cm long. I made the shape with books and all sorts of things and it looks pretty long but i guess when its actually made it will look better.

Alright now some good news. Totally length of tubing needed for old frame:7.2m Total length of tubing needed for new design:7m

What do u know, its slighty lighter. THATS AWESOME! Sorry for saying it wouldnt be in the last post guys, i forgot that the wheels needed to go on and that added length to the total width of the kart. Stupid me!

EDIT: Getting my clutch, chain and possibly sprocket tomorrow!
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Old 12-23-2008, 04:08 PM
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Sounds like you're well on your way to nice kart
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Old 12-23-2008, 05:49 PM
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**** yeh! My uncle works in the bush and he said he will give me a brand new honda 6hp for free. He bought it for 800 bucks but it never got used, it was meant for a generator but when he bought the new motor for it the other guy had already bought one so hes going to give it me next time he comes down to my house which could be a while now but still, i get a 6hp honda on it one day.
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Old 12-23-2008, 06:04 PM
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If it was for a generator, it may have a tapered shaft.
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Old 12-23-2008, 07:07 PM
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i hope not. meh we shall wait n see. Ill probably hav a 5hp by the time he comes down to my house lol.
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Old 12-27-2008, 03:42 AM
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Some updates on the kart:
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Old 12-28-2008, 04:17 AM
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Another Update:
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