Post by bigscoot on Sept 13, 2014 12:30:26 GMT -5
urbanmadness, our engine must be a 4 stroke to run in the competition we are building this for.
This is all helpful. We have been looking into the problem of valves colliding with the piston. Do you think fly cutting the pistons would not be enough? The timing chain is not something we have looked into yet.
One thing we are thinking about right now is to take possible a 125cc gas engine and sleeve and possible grind it to get it closer to 50cc. Our thoughts we this is that the bigger bottom end could hold up better to the diesel and high performance parts are more readily available for a 125cc. A whole new head may still have to be fabricated though.
We aren't worried about getting 100,000 miles out of our engine but we do want it to run reliably for competitions for years to come.
Going with the four stroke makes it a lot harder, as you will need to figure out how to increase the compression without having the valves collide with the piston so at the very least you will need to grind a cam for it. The extra compression is also going to be hard on the timing chain and it's a very tiny chain. Remember the compression will have to be in the neighborhood of 18:1 for it to light off.
If you do a four stroke, your going to have to machine a head (cnc out of a bullet) with valves, valve seats and ports, your gonna have to grind a cam, and make a piston. The four stroke will have a wider torque curve, but will not make as much low end as the two-stroke. You will need some sort of injection.
If you do a four stroke, your going to have to machine a head (cnc out of a bullet) with valves, valve seats and ports, your gonna have to grind a cam, and make a piston. The four stroke will have a wider torque curve, but will not make as much low end as the two-stroke. You will need some sort of injection.
This is all helpful. We have been looking into the problem of valves colliding with the piston. Do you think fly cutting the pistons would not be enough? The timing chain is not something we have looked into yet.
One thing we are thinking about right now is to take possible a 125cc gas engine and sleeve and possible grind it to get it closer to 50cc. Our thoughts we this is that the bigger bottom end could hold up better to the diesel and high performance parts are more readily available for a 125cc. A whole new head may still have to be fabricated though.
We aren't worried about getting 100,000 miles out of our engine but we do want it to run reliably for competitions for years to come.