can 80cc twostroke run backwards

[gperc5]

need to change timing?

 

[butre]

changing the timing will be all you need to do. the easy way will be with a manic mechanic adjustable magnet

 

[GreenMantis]

Couldn't you just flip the magneto coil around the other way? Or rotate it 180 degrees, whichever way you look at it.

 

[crassius]

too early in AM to think well on it, but if slot in shaft were right at TDC that might work - our slots aren't there tho

 

[GreenMantis]

Are you sure? I thought that the slot for the key at 12 oclock was ALWAYS TDC, it's like a universal rule of mechanics and engine design. And with 4 strokes, likewise the pin in the camshaft. When both of those are at zero degrees, that's always TDC for cylinder #1. You do mean the woodruff key on the crankshaft, right?

My dirt bike started backwards a couple of times, just because I dropped it too hard.

 

[KCvale]

Is this to run a shifter by turning a 2-stroke around and running the engine backwards?

 

[Murkle]

How about we stop asking why, and just do our best to answer. I would think a 2stroke could run backwards fine, but I don't know what changes you might have to make.

 

[Street Ryderz]

Are you sure? I thought that the slot for the key at 12 oclock was ALWAYS TDC, it's like a universal rule of mechanics and engine design. And with 4 strokes, likewise the pin in the camshaft. When both of those are at zero degrees, that's always TDC for cylinder #1. You do mean the woodruff key on the crankshaft, right?

My dirt bike started backwards a couple of times, just because I dropped it too hard.

These engines have the keyway cut between the 12 and 1 oclock position when the piston is at tdc and this gives 18-20 degrees btdc for the 12 oclock and 23-25 degrees btdc for the 1 oclock position and I've never seen a two stroke timmed at zero or tdc it wouldnt work because as the rpm climb the timming would be atdc and make no power.

 

[gary55]

How about we stop asking why, and just do our best to answer. I would think a 2stroke could run backwards fine, but I don't know what changes you might have to make.

Of course it could be done by making the timing the same in reverse as it is currently in forward. The question why is still valid though as the intended use may be more easily achieved by another means.

 

[crassius]

I've several times seen a bad CDI start a motor backwards - the timing on it had totally gone bad. Were I to do it, I'd cut a new locating slot in rotor.