*Bear in mind I do not have a speedo cable, therefore I do not know.*
Is it just me or do sprees go faster if you turn off the engine and let it coast down by itself while going downhill... I know I do it because it saves gas. (my hill is fricken steep and about a mile and a half long). It certainly feels like im going faster, but that might be the fact that the only noise I hear is the air going past, not the familiar engine sounds. But cars still pass me at the same speed... I really need a speedo cable lol
I think you're actually NOT going as fast - you have the both drag and braking power of the belt and pulleys rotating.
Leave the engine running and open it up....you'll go faster if speed is what you want.
You still have the drag of the tranny and the flywheel (outer clutch) dragging. Same as riding the brakes. You aren't about to over-rev the two stroke. Try it and you'll see what I mean.
I've done the same experiment before. One mile hill vs one and a half but results were the same. My speedometer(s) work fine and they all have the same result, more speed with the throttle open vs closed.
I'd love to see some documentation on speed limiting on the Spree. Red Line too as far as that goes. Most of my knowledge comes from experience. I have tried (unsuccessfully) to get documentation, please tell me where.
Doubt there's much; the CDIs are called "black boxes" for a reason. If you have a frequency generator and a event counter/oscilliscope you could probably figure out the ignition timing and RPM limit. I'm betting it's really simple, like a single-set ingnition advance setting.
I've read that disconnecting the "red wire" from the CDI disables the rev limiter. There is no red wire, only a black/red on 84/85 that is picking up a voltage off the mag. Looks suspicious. Don't know about 86 or 87.
I've had an O'scope on and read the pulses and got to 10k. Frequency generator couldn't put out more. That tells me that since this is a single fire triggering CDI, the 'red line' is at least 10K but obviously more......
Accepting for losses in the line due to stray capacitance, the electrical portion is good for a lot higher RPM than the mechanical, but I still don't know what that is.....
Complete bench setup. My only limitation was a ten k generator. Coil never hesitated, plug didn't either. I admit that I was nervous with the plug fairly close to my arm, but it stayed safe enough. Used a 12 volt filtered power supply by the way, never took into account that the generator would be pulsed output vs flatline, although it shouldn't make a huge difference.
Did you happen to check the phasing of the input to output? I was wondering if the black box had variable ignition advance, or if it was set to one value.
Not variable. Capacitance trigger. Time constant changes with frequency but only to a small degree.
I'm still interested in knowing what the mechanical limit is. I'm assuming that this is where any limiting would come into effect with the air flow restrictions and exhaust etc.
