550 lc arctic kart

[jmorga10]

hey guys im new to kart building and need some pointers. i want to make a TWO MAN kart powered by a 550 liquid cooled arctic cat snowmobile motor. i have the motor and some pipe, a set of rear tires, a set of front tires, seatbelt webbing. what kind of welder should i use? keep it cheap if possible, i know this isnt a cheap thing to do but i got the pipe for $30 the engine for free, the rear tires from a 300ex pretty much nib $40 front tires from a quadzilla for $60. what else do i need?

[jrjulien1]

if your planning to use an engine like that i suggest you use at least 1 good disc brake {6in or larger} and a high stregnth axle 1in thick and a 4 pillow block berings to hold the axle on the frame and as for the frame i think you should have two tubes running on an angle to form a triangle with bracing in the middle like the one shown here at northern tool hope this helps http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_22122_22122

[jmorga10]

yeah i figured id have to have at LEAST a 1 inch axle. i was considering a 1 1/4" axle but accessories like brakes and hubs are harder to find. i was thinking i could probably adapt the front suspension and steering from the snowmobile as it is quite sturdy. oh yeah any body have an idea what kind of welder i would need? dont i wont be the guy that doesnt know how to weld and kills him self on a powerful kart, my mom has about 20 yrs experience welding so she will probably weld most of it. i know its gonna be fast but how fast? figure were talking its turning 22" ohtsu quad tires and pushing two people.

[jrjulien1]

well if your mom knows how to weld good then maby you should consider a stick welder as they are cheap but are hard to use if you dont know how to however if you want an easier to use type of welder a mig welder might be right for you but they cost more than a stick welder {starting at around $80 for a stick welder and $250 to $300 for a mig welder.

[jrjulien1]

as for how fast its going to go that depends on how low or high the gear ratio is a i suggest you use a low gear ratio to maximize torque for off roading {assuming thats what its going to be used for} but if you use a large sprocket on the axle 80 kmph is very achieveable and very scary however if you use a higher gear ratio you could easily reach
100+ kmph which is VERY fast for a go kart but if you choose this option your low speed travel will suffer and make it harder to use off road

also look at this website it might give you some ideas
http://www.nitrostreet.com/gocart.html

hope this helps

[jmorga10]

i would probably rather just have it do like 70mph and have tons of ripping power. i dont know what my gear ratio would be if i use the clutch and driven pulley from the snowmobile but thats what i wanna do. i know that if i want to be able to change gear ratios id have to use a jack shaft and unihub and then change on the hub and at the jack shaft. which do you think is better plan?

[jmorga10]

im noticing that the sprockets i can find using 520 chain have a weird mount that wont work right on regular kart axles. do you think that if i were to run my belt from engine to a jackshaft and have a sprocket at each end one for each end of the axle then do you think 41 or 40 chain would handle the stress of a 550 snowmobile engine? i just didnt think that one 41 or 40 would hold up to it.

[jrjulien1]

i think that two 141 chains would hold up to the stress of a 550 engine

[jmorga10]

ive decided i want a topspeed of 70mph what gearing should i start at for this?

[jrjulien1]

well im not sure what gear ratio but this website might help http://webpages.charter.net/jeffparker/speed_calc.htm {i would suggest a 9in sprocket might be in the right area}

hope this helps

[jrjulien1]

i did some figureing and i found that a 11tooth drive sprocket and a 72tooth driven sprocket at 5000 rpm {i think your motor will hit around there} will give you a 50mph top speed but with the weight a 40mph top speed will be around where it will max out whilst this isnt very fast it will be a great off road kart or you could swap the driven sprocket out for a 60tooth and hit around 50 which will still be good off road

hope this helps

[jmorga10]

see the ting is thats just where my motor starts gettin good it redlines at 8000 its a high rev snowmobile motor cus its 2 stroke

[jmorga10]

yeah confirmed i just went out and checked. my engine enters powerband at 5000rpms and redlines at 8000rpms.

[jmorga10]

i used the calculator and even figuring in weight since my motor redlines at 8000 it would hit 55 with a 10 tooth drive sprocket and 80 tooth driven sprocket. its all about the rpms and this engine can make lots of em. its tachometer goes up to 10000 but as i said redlines at 8000.

[jrjulien1]

ya 55 sounds like a good top speed but dosent the motor from the snowmobile have a cvt
attached to it which would raise the top speed {a cvt is a constantly variable transmission its like having an infinite gear trans}

hope this helps

[jmorga10]

i thought so as well but upon inspection it looks like its just a huge better built centrifugal clutch.

[jmorga10]

i guess it is a cvt system. im confused. anyway im gonna start with a 6:1 ratio and work from there.

[jrjulien1]

ok since it has a cvt you might wnat to go with the gear ratio from the snowmobile and work from there