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June 3, 2011 6:30 AM
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Builder: Larry Erd, Pompano Beach, Fla.
Plans: [You must be registered and logged in to see this link.] "Black Widow"
Cost: $689.15
Erd and his 7-year-old son, Harrison, used $14.99 plans for the "Black Widow" go-kart from [You must be registered and logged in to see this link.]. Plans like these, whether they are free or require a fee, often give frame dimensions but leave steering, axle, throttle and cable connections up to the builder. Browse parts suppliers' websites to find additional advice on materials and methods. "You're on your own, but that's the fun of it," Erd says.
Use a hacksaw or chop saw to cut metal stock to length. Clamp the steel in a vise and file or grind the cut edges smooth. Using a MIG welder, tack together the parts to check for a good fit, and make final welds to complete the frame.
Weld an upper steering block to the top of the kart's steering post. Weld the lower steering block to the front of the frame. Screw the steering wheel to the steering shaft and thread the shaft assembly through the upper and lower blocks. Bolt a pair of spherical rod ends to the steering arm at the bottom of the shaft, using nylock nuts.
Weld spindle brackets to the front corners of the frame. Bolt the tie rods' opposite ends to the brackets' arms and connect the rods to both ends. Thread each bracket's stub axle into the front wheels' hubs. Mount the front tires on rims and bolt the rims to the hubs. Erd adjusted the positions of the steering shaft and tie rods until the steering performed properly.
Weld bearing hangers to the bottom face of the frame's 10-inch rear legs. Center the sprocket, Uni-Hub and brake drum on the axle. Wedge bearings between a pair of bearing cassettes and use the hardware in a bearing kit to fasten the cassettes to both hangers. (Expect to adjust the axle parts again.) On the axle ends, mount wheel hubs, fit rear tires onto the rims and bolt the rims to the wheel hubs.
Buy accessories together with the engine to ensure compatibility. Weld a mounting plate to the rear center of the frame, and bolt the engine to it. Add a clutch to the engine crankshaft using set screws in the clutch hub. Slide the Uni-Hub along the axle to align the axle sprocket with the clutch sprocket. Weld a bent 3/8-inch rod to the frame so it crosses in front of the brake drum to anchor the brake band. Tighten the set screws on the Uni-Hub, drum and bearings.
Loop chain around both sprockets. Remove links to adjust the chain so it has ½ inch of play.
Attach brake and throttle cables to the left and right foot pedals. Lead cables to the rear and fasten the sheaths to the frame. Pull cables just to the point of tension. Use wire stops to pin the brake cable to the upper end of the brake band so that the band can cinch around the drum to arrest the axle's motion. Pin the throttle cable to the engine throttle in the idle position. Mount a kill switch; lead the cable to the engine.
Start the engine with the kart on blocks to test the pedal connections. Erd added a floorboard so a driver wouldn't kick the tie rods (or the ground).
Make a seat by stapling vinyl and foam cushioning to plywood. Bolt it, and a seatbelt, to the seat post and the frame.
Harrison drives wearing a helmet, seatbelt fastened, while Erd supervises—and the boy has survived to see age 14.
[You must be registered and logged in to see this link.]
Of four sites consulted for parts and tips, this was the best. Great diagrams and advice. Louisiana expert Chet Dowden offers kartbuilding wisdom by phone or email. Motto: "In thrust we trust."
[You must be registered and logged in to see this link.]
Comprehensive but cluttered parts lists, with scant description of parts' functions. Erd was satisfied shopping here. Owner Steve, unreachable by phone, did not reply to an emailed question.
[You must be registered and logged in to see this link.]
A fine source of diagrams, racing tips and technical info. No parts are for sale, and no phone number is listed on the site. An emailed form request to "talk karts" was never answered.
[You must be registered and logged in to see this link.]
Not helpful by phone, but emailed questions get a prompt response from either Bill (the owner) or Bill (the tech support). A wide parts selection reflects the staff's kart-racing expertise.
Builder: Larry Erd, Pompano Beach, Fla.
Plans: [You must be registered and logged in to see this link.] "Black Widow"
Cost: $689.15
1.) Plans and Parts
PRINTABLE PLANS
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[You must be registered and logged in to see this link.] (PDF, .3MB, requires [You must be registered and logged in to see this link.])
Erd and his 7-year-old son, Harrison, used $14.99 plans for the "Black Widow" go-kart from [You must be registered and logged in to see this link.]. Plans like these, whether they are free or require a fee, often give frame dimensions but leave steering, axle, throttle and cable connections up to the builder. Browse parts suppliers' websites to find additional advice on materials and methods. "You're on your own, but that's the fun of it," Erd says.
2.) Frame
Use a hacksaw or chop saw to cut metal stock to length. Clamp the steel in a vise and file or grind the cut edges smooth. Using a MIG welder, tack together the parts to check for a good fit, and make final welds to complete the frame.
3.) Steering
Weld an upper steering block to the top of the kart's steering post. Weld the lower steering block to the front of the frame. Screw the steering wheel to the steering shaft and thread the shaft assembly through the upper and lower blocks. Bolt a pair of spherical rod ends to the steering arm at the bottom of the shaft, using nylock nuts.
Weld spindle brackets to the front corners of the frame. Bolt the tie rods' opposite ends to the brackets' arms and connect the rods to both ends. Thread each bracket's stub axle into the front wheels' hubs. Mount the front tires on rims and bolt the rims to the hubs. Erd adjusted the positions of the steering shaft and tie rods until the steering performed properly.
4.) Rear Axle
Weld bearing hangers to the bottom face of the frame's 10-inch rear legs. Center the sprocket, Uni-Hub and brake drum on the axle. Wedge bearings between a pair of bearing cassettes and use the hardware in a bearing kit to fasten the cassettes to both hangers. (Expect to adjust the axle parts again.) On the axle ends, mount wheel hubs, fit rear tires onto the rims and bolt the rims to the wheel hubs.
5.) Engine
Buy accessories together with the engine to ensure compatibility. Weld a mounting plate to the rear center of the frame, and bolt the engine to it. Add a clutch to the engine crankshaft using set screws in the clutch hub. Slide the Uni-Hub along the axle to align the axle sprocket with the clutch sprocket. Weld a bent 3/8-inch rod to the frame so it crosses in front of the brake drum to anchor the brake band. Tighten the set screws on the Uni-Hub, drum and bearings.
Loop chain around both sprockets. Remove links to adjust the chain so it has ½ inch of play.
6.) Cables
Attach brake and throttle cables to the left and right foot pedals. Lead cables to the rear and fasten the sheaths to the frame. Pull cables just to the point of tension. Use wire stops to pin the brake cable to the upper end of the brake band so that the band can cinch around the drum to arrest the axle's motion. Pin the throttle cable to the engine throttle in the idle position. Mount a kill switch; lead the cable to the engine.
Start the engine with the kart on blocks to test the pedal connections. Erd added a floorboard so a driver wouldn't kick the tie rods (or the ground).
Make a seat by stapling vinyl and foam cushioning to plywood. Bolt it, and a seatbelt, to the seat post and the frame.
Harrison drives wearing a helmet, seatbelt fastened, while Erd supervises—and the boy has survived to see age 14.
Parts-Supplier Reviews
[You must be registered and logged in to see this link.]
Of four sites consulted for parts and tips, this was the best. Great diagrams and advice. Louisiana expert Chet Dowden offers kartbuilding wisdom by phone or email. Motto: "In thrust we trust."
[You must be registered and logged in to see this link.]
Comprehensive but cluttered parts lists, with scant description of parts' functions. Erd was satisfied shopping here. Owner Steve, unreachable by phone, did not reply to an emailed question.
[You must be registered and logged in to see this link.]
A fine source of diagrams, racing tips and technical info. No parts are for sale, and no phone number is listed on the site. An emailed form request to "talk karts" was never answered.
[You must be registered and logged in to see this link.]
Not helpful by phone, but emailed questions get a prompt response from either Bill (the owner) or Bill (the tech support). A wide parts selection reflects the staff's kart-racing expertise.
