Originally Posted by
kmeyers
I know I'm slow at providing good info, but, here are some thoughts.
The high quality 50cc DA single I have likes a 22 x 8 @ ~ 7000 rpm. I ran an early 40cc SPE for years with a 20 x 8 @~ 7300 rpm. I ran a ST 3250 on a 18 x 6 @ ~ 10500 rpm with glow 0% nitro.
Point: A twin 4 cycle conversion will not match the same as a single 2 cycle of equal displacement.
Conclusion: Be happy, Don't worry. I think you are close to where you should be.
Yes try different props, carbs, even plug gaps, maybe little timing changes and fuel oil ratios.
In the end, put that bad boy in the air and enjoy!
Thanks GG and K! It's great to have interested parties involved in the conversion process. Wouldn't be the same with you guys!
I have a sneaking suspicion that this particular Xoar prop could very well be causing some of the missing RPM. There's really no telling and you are right K, I should be, and am, happy with it right now. I've mentioned elsewhere in this thread that I'm building a 50% Bucker Jungmiester so I'm jumping back on that. But some day in the not too distant future I WILL be designing a perfect plane for this engine. Like I mentioned, I'm shooting for a vintage looking biplane: very much like a bipe version of the Rascal but sized up to fit this engine. I already love my Gemini powered Rascal 110 with a burning passion so a big bipe that I designed/built and with this big Gemini would really be a dream come true for me.
I needed to make a decent choke lever to complete the project so here's some final eye-candy.
In this pic you see i downsized the hole in the choke plate. Needed more vacuum.