G'day, Mick from Oz here.

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micka80

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Thought i would do my first post here and explain my goals and seek advice in the one post.

So, i have decided to take up this hobby as i have two little kids - one 3 and one 3 months and have this vision in my head of building a little train like kart so each kid has their own carriage. As they get older i would like to hopefully transfer the parts onto a more suitable frame.

First question
I am so far thinking a 6.5hp engine geared correctly to slowly putt around our yard (max speed - 5 to 10). Is this achievable for these little engines?

Second question
Here is a link to a axle kit i have been looking at http://www.cutpriceracing.com.au/st...OJECT-series-with-Weld-on-Brackets-AXC408PB1/
It seems expensive but if add the price of all the bits together it seems good and also the parts are common and reusable, what i am asking is related to the axle, the keyways are cut in specific sections and it also too long for what i want. Is there any way of getting the same axle but with a full length keyway that is not too expensive?

Final question
Torque converters - i see the one i am looking at states a 2.7:1 initial drive ratio, can the Kart be driven at low speeds/revs without fear of burning it out like a centrifigal clutch? Also my brain is hurting trying to work out the speed - if 1(lets call it top gear) is 10kph and 2.7 is first gear, is first gear 2.7kph or is it 10-2.7= 7.3kph?

So thats it for now, i have heaps more researching to do before i start gathering components, still debating though as to go for clamp together good quality and easily transferable or just start welding sprockets to steel bar, cheap everything etc, or even just buy a chinese go kart and strip it down.

Thanks in advance for all the helpful info this site delivers.
Mick.

Edit - What about buying a second hand race kart, use components to make the little train and when ready go back to the race frame with say some offroad tyres?
 
landuse

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micka80 said:
Thought i would do my first post here and explain my goals and seek advice in the one post.

So, i have decided to take up this hobby as i have two little kids - one 3 and one 3 months and have this vision in my head of building a little train like kart so each kid has their own carriage. As they get older i would like to hopefully transfer the parts onto a more suitable frame.

First question
I am so far thinking a 6.5hp engine geared correctly to slowly putt around our yard (max speed - 5 to 10). Is this achievable for these little engines?

Second question
Here is a link to a axle kit i have been looking at http://www.cutpriceracing.com.au/st...OJECT-series-with-Weld-on-Brackets-AXC408PB1/
It seems expensive but if add the price of all the bits together it seems good and also the parts are common and reusable, what i am asking is related to the axle, the keyways are cut in specific sections and it also too long for what i want. Is there any way of getting the same axle but with a full length keyway that is not too expensive?

Final question
Torque converters - i see the one i am looking at states a 2.7:1 initial drive ratio, can the Kart be driven at low speeds/revs without fear of burning it out like a centrifigal clutch? Also my brain is hurting trying to work out the speed - if 1(lets call it top gear) is 10kph and 2.7 is first gear, is first gear 2.7kph or is it 10-2.7= 7.3kph?

So thats it for now, i have heaps more researching to do before i start gathering components, still debating though as to go for clamp together good quality and easily transferable or just start welding sprockets to steel bar, cheap everything etc, or even just buy a chinese go kart and strip it down.

Thanks in advance for all the helpful info this site delivers.
Mick.

Edit - What about buying a second hand race kart, use components to make the little train and when ready go back to the race frame with say some offroad tyres?
Click to expand...

Welcome to the forum mick!!

If you gear your train correctly (very low), a 6.5HP engine should be fine to get you around.

If I were you I would just make your own axle. You can buy the steel bar, bearings etc seperate, and it would work out a lot cheaper than the kit you linked. Also NEVER NEVER NEVER WELD ANYTHING TO YOUR AXLE. Use keys and keyways to keep it all together. You never know when you want to change things, and welding weekens the structural integrity of the axle.

To gear low you are probably going to have to use a jackshaft which allows compound gear reduction. I would probably gear around 15 or 20:1. You wont go fast at all though.

If you can, try buy a used frame from gumtree or something like that for parts.

A torque converter is also a good idea to use, but you cannot use it at high gear ratios like 2 or 3:1. You will just shred belts like you would burn up a centrifugal clutch. They do handle higher ratios than a cent clutch, but not that high.
 
OzFab

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:welcome2: It's about time we had another Aussie join in...

micka80 said:
First question
I am so far thinking a 6.5hp engine geared correctly to slowly putt around our yard (max speed - 5 to 10). Is this achievable for these little engines?
Click to expand...

If you're lucky enough to find one, get yourself a GX200 clone with a 6:1 reduction gearbox which also have a wet clutch, gear down between the output shaft & the axle & you should be going pretty slow...

These engines actually work better when geared down as they don't have masses of torque &, if you're towing a load, even better...

micka80 said:
Second question
Here is a link to a axle kit i have been looking at http://www.cutpriceracing.com.au/st...OJECT-series-with-Weld-on-Brackets-AXC408PB1/
It seems expensive but if add the price of all the bits together it seems good and also the parts are common and reusable, what i am asking is related to the axle, the keyways are cut in specific sections and it also too long for what i want. Is there any way of getting the same axle but with a full length keyway that is not too expensive?
Click to expand...

As landuse stated, it would be cheaper to have an axle made from a solid round bar & have a full length keyway cut in it; it would be really handy if you know someone who works in a machine shop...

I find ebay is a good source of used parts such as hubs & wheels, you just have to be patient...

Bearings are easy to find, either pillow blocks or flange type bearings & carriers can be sourced at your local CBC Bearings Supply (there's one in Burleigh Heads) or similar store...

micka80 said:
Final question
Torque converters - i see the one i am looking at states a 2.7:1 initial drive ratio, can the Kart be driven at low speeds/revs without fear of burning it out like a centrifigal clutch? Also my brain is hurting trying to work out the speed - if 1(lets call it top gear) is 10kph and 2.7 is first gear, is first gear 2.7kph or is it 10-2.7= 7.3kph?
Click to expand...

Although torque converters are great, IMO, not the best choice for this particular project; I'd stick with either a centrifugal clutch or, as previously mentioned, a wet clutch...

micka80 said:
So thats it for now, i have heaps more researching to do before i start gathering components, still debating though as to go for clamp together good quality and easily transferable or just start welding sprockets to steel bar, cheap everything etc, or even just buy a chinese go kart and strip it down.
Click to expand...

As landuse already stated,

landuse said:
NEVER NEVER NEVER WELD ANYTHING TO YOUR AXLE.
Click to expand...
 
OzFab

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You are right, a 6:1 is hard to find. If say i got a 2:1 model and geared as low as possible, how does one know the clutches rpm limit so it it is not constantly slipping. If i use a calc i come up with 7kph@1000rpm and 12kph@1800rpm using a 9 tooth drive sprocket and a 85 tooth driven with 13 inch tyres. Now 7kph is a slight bit quicker than i wanted for lets say driving around a tree but 12kph would be fine if not ideal for a nice straight run. Do these clutches tolerate much slower speeds?
 
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No offence but, I think your math is off...

Using our speed calculator I get 7mph@3600 engine RPM...

How did I get that? For starters, factor in the reduction which means, at 3600 engine RPM (governed speed) the redux output will be at 1800rpm...

Just another point, think about your sprocket sizes in relation to what they attach to; a 85t #35 sprocket has a diameter of just over 10"; with 13" tyres, that only leaves less than 1" (25.4mm) of ground clearance; yes, I know, 13-10=3, not 2 but, tyres flex, you need to account for that plus the width of the chain...

Likewise, a 9t #35 has an outside diameter of 1.25", subtract 3/8" for the depth of the teeth & you're left with 7/8"; what size is the output shaft?
 
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Cheers for all the help. I ended up getting an old rover colt 5hp ride on for parts as the wheelbase is nice and narrow, but low and behold it actually works fine - bit of air in the tyres and fired her up, heap of smoke at first but runs sweet as, even cuts the grass, not bad for $100. Just gotta give it a good service and replace the muffler and i got a good platform to work with, it goes real slow and climbs our steep driveway with ease. I will start a new thread when i get crackin on it.
 
OzFab

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PERFECT! Those old rover colts seem to go forever & there should be somewhere on the rear to mount some sort of tow hitch...
 
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