How to Change a CR80 to a CR125 Shifter Kart
- 1). Set the a scale under each tire of the shifter cart. If you happen to have ultra-sensitive load sensors, those are even better. Sit the driver in the driver's seat and not the weight or load on each tire. Calculate the ratio of front-to-back weight distribution and side-to-side if there is any.
- 2). Determine whether you want to experiment with the distribution a little, or try to maintain the distribution with a new engine.
- 3). Remove the chain. First remove the master-link with a flat screwdriver, then using a chain breaker, if necessary, to slid the main link apart.
- 4). Turn the fuel petcock off. Disconnect the fuel line and remove the carburetor of the CR80.
- 5). Remove the motor mount bolts of the CR80, then lift the engine from the frame.
- 6). Cut two pieces of 2-by-2-inch lumber the width of the kart frame and lay them across the frame to use as a temporary cradle to help position the new engine. A standard 8-foot or stud-length board should be long enough. Fasten them temporarily with zip-ties -- ratcheting nylon bands that cinch in place.
- 7). Set the CR125 engine on the wood blocks with the kart still on the scales. Sit the driver in the car and measure the load distribution.
- 8). Evaluate which direction the engine has to move to match the weight distribution of the smaller engine. Most likely, the engine will have to be moved closer to the center of the kart.
- 9). Adjust the engine until to find the weight distribution you want. Measure the engine relative to the frame. Make a couple reference marks on the engine for positioning.
- 10
Remove the scales and the pieces of wood. - 11
Lay small squares of plywood about 12-by-12 inches under the frame where the engine will go. Build up the shims until the engine can sit on them at the appropriate height at the alignment you marked. Using typical width plywood of 1/2-inch, you'll need about four shims for every inch off the ground the engine will sit. One sheet of plywood will be more than enough, stacking 4-inches high. Should you need to stack higher, you can start with two bricks and stack the shims on top of those. - 12
Measure from the CR125s engine mount holes to the nearest or most logical frame member for mounting. - 13
Fabricate four motor mounts from steel tubing, using an angle grinder and abrasive wheel to cope the end of the tube to fit the frame. - 14
Weld a flat tab on the other end of each mount to fit flush to the motor mount, then drill a hole in the tabs the same diameter of the motor mount bolts. - 15
Weld four motor mounts in place. - 16
Hold the CR125 motor in place and slide the mounting bolts in place.
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