Bdegan
50cc
Ok.....
Had the chance to play with the motor some more.
I tried a Beila 22x12 3-blade. Quite a high load prop. Using the same 8.5 inch header length as the 25x8W, the Beila 3 blade gave me 5940 rpm. Then I tried it with the stock mufflers. Turned 6000.
Going back and looking at the 25x8W results. And then the 24x9 results. It was quickly realized that different header lengths are required for different sized props. That is the case with other engine and prop combos. But I had never seen as drastic a change in header length required as with this set up.
Here is a short summary of my findings.
25x8 wide worked best at 8.5 inch header length.
24x9 turned 7380 stock muffler and 7480 at 8.5 inch header.
22x12 3-blade turned 6000 stock and 5940 at 8.5 inch
Based on the results I got. The 24x9 ( lighter load prop ) would require a shorter header. And the 22x12 3-blade ( higher load prop ) would require a longer header.
I worked my way down to 7 inches with the 24x9. Ended up at 7630 rpm. I couldn't go shorter with the header because it is all the way at the flex section . Just enough pipe past the flex to get a clamp on the coupler.
So Falcon 24x9
7380 @ stock mufflers
7480 @ 8.5 inch
7630 @ 7 inch
Beila 22x12 3-blade
6000 @ stock mufflers
5940 @ 8.5 inches
5980 @ 11 inches
6140 @ 12 inches.
I could have tried a longer header. But even at 12 inches, insallation could be problem. Longer , even worse.
Conclusion, is that these pipes on the DA70 twin have a very broad tuning range depending on the prop you want to run and what style of flying you like.
You almost need to know what prop you want to run before hand. Then tune accordingly.
