Stephen115's homemade kart

[EC1]

Nice build. I just have one observation. I see that your rear axle is really long, and that your rear wheels sit far away from the frame. You might have a problem with that, in that you might bend your axle there. The best way to prevent this is to have the rear wheels as close to the frame as possible, or some sort of support bearing.

Originally Posted by Stephen115
^ which side should I put the bearings on, outside or inside the brackets?
also have some pretty big news! just ordered a 1988 Yamaha yz250 2 stroke w/dual radiators, all it needs is a carb and shifter return spring. Pretty stoked, this thing is going to fly.

whichever way will give you more room.

moving your bearings to the outside will in effect stiffen your axle by reducing the distance between the wheels and the frame (as described above). I wouldn't see the need for a third bearing support. You would then have more clearance for your driven sprocket.

[Stephen115]

I understand about 50/50 of what EC1 is saying, I'm new to the whole geometry and camber/caster. so the #520 sprocket and hub wont work? or I just need to weld it to the axel when I get it?

also could use some electrical help here, as you know I have the yz 250 and I ordered the ignition coil cause it didn't come with it. well I got new spark plugs and a carburetor and I've been already to start this beast up...no spark. so I got my voltage tester out to test the coil and there is no power going to the sparkplug nor the spark plug connector on the ignition coil. If anybody is confused I can show a video of what is happening.

thanks
SJ

[EC1]

Hopefully this is legible

[anderkart]

Originally Posted by Stephen115

I ordered the ignition coil

Did your coil come with a CDI box like this one? http://www.ebay.com/itm/1988-YAMAHA-...sories&vxp=mtr

[Stephen115]

Originally Posted by anderkart

Did your coil come with a CDI box like this one? http://www.ebay.com/itm/1988-YAMAHA-...sories&vxp=mtr

yes

[EC1]

Check out the picture. This is Ackerman Steering.

Currently your steering arms are parallel (bad). If you were to keep it unchanged, when turning, both inside and outside angles would be equal thus scrubbing the outside tire with tons of understeer.

The outside wheel should turn at less of an angle then the inside for optimum steering.

[EC1]

camber on a rigid vehicle with a locked axle lifts the inside tire off the ground (or unleast unweights it). As the vehicle turns the inside tire has to travel a shorter distance than the outside tire. It's trying to keep going straight. Lifting the inside tire lets three points (the two front + outside) follow those turning circles.

[Stephen115]

Originally Posted by EC1

Check out the picture. This is Ackerman Steering.

Currently your steering arms are parallel (bad). If you were to keep it unchanged, when turning, both inside and outside angles would be equal thus scrubbing the outside tire with tons of understeer.

The outside wheel should turn at less of an angle then the inside for optimum steering.

I dont have any way to change it, i'm too far into my build. i'll just have to deal with it until I get a racing frame or build another.

do you have any advice on the electrical problem i am having, stated above?

[EC1]

how do you do with electrical diagrams? the web has tons of images on a yz250 coil/stator/kill switch wiring.

I wouldn't try and get a voltage reading with a meter - you'll destroy it quite easily. I would wire the stator and coil up and look for an arc between the plug and ground as you give it a good kick.

The kill switch wiring is one area to check if you're not getting spark.

[Stephen115]

So the stator has to be engaged in order to start? And which wires are the kill switch?

[EC1]

If you post good pictures of the coil, wires coming out of the motor (stator) and lastly the cdi box, I think I can tell you what wires to connect together.

Get a good shot of each wire and their colors.

[Stephen115]

here ya go

[EC1]

blk to ground at coil. ground the coil. leave blk-wht open. connect everything else as you show.

[Stephen115]

ok, ill try it tomorrow. thank you

[Stephen115]

Still no spark, do both sides of the coil have to be grounded? also, i'm using a vise grip on the kick start because I don't have the kick start. could it be that i'm not turning it enough for it to spark?

[Stephen115]

I managed to grind down another kick start i had and it works good for now but still not starting or sparking...

[EC1]

both sides of the coil do not need a ground.

[EC1]

Stephan - black (of the kill switch wiring) to ground at the coil. Ground the coil. Leave the blk/wht open. connect the orange wires.

I think this will work..

[Stephen115]

We have Spark!

[Stephen115]

o-ring chain or non o-ring chain for my kart? and which brand would be the best to get? I'm using a #520 chain.