Hey guys,
I have successfully got a Tiger Drive rotor start to fit onto the kyosho gx21 engine.
It required some modification of the mounting bracket for the engine. I needed to widen the mounting holes in order to allow the motor to move slightly closer to the front of the chassis giving more room for the exhaust muffler. I also needed to craft a 2-3mm thick aluminum plate in between the exhaust port and the exhaust manifold (acts as a spacer) due to the fact that the rotor start is a bit bigger than the pullcord.This also meaned that I needed to file the exact size hole for the exhaust gas to flow through and also drill 2 small holes to allow the exhaust manifold bolts to pass through.
Since the output shaft on the kyosho engine is about 8mm thick, I got the *s681 90 degree drive system*
http://sullivanproducts.com/tiger-drive/
Essentially there are 2 gears. 1 that contains a 1way bearing attached to the crank output (recommend to apply a good amount of grease) and another gear at a 90 degree angle (see picture)
Once that was done, I sealed the spacer with high temp silicone (works so much better than the gasket that was originally provided in the model space kit).
I also added a bit of grease in the rotor start gears and siliconed everything together. The tiger drive system has an aluminum plate and a plastic cover that goes over the gear. I had to file down the aluminum plate in order to reduce the size of the entire thing.
The kit should come with a hex bit that has a ball shaped end which allow you to have the bit at a angle when starting. I simply hook up my cordless drill on the end and give her a few taps on the trigger.
hawkboy000 attached the following image(s):