I accidentally deleted the entire thread by mistake. So I recreated it here again. Sorry.
A while back I had acquired a SV-17cc engine. At the time the reviews weren't all that good for it either. But the price was right, so I couldn't resist.
When I first ran the engine, I found that I couldn't lean it out enough to run at its top speed. It stayed blubbery rich even with the needle valve all the way out, ready to fall out even. So when I looked at the carb I found that it had a Walbro WT-694 carb on it with a 12.7mm venturi bore, which I thought was way too big for a 17cc engine. As I have seen them a carb with around a 9mm venturi is about right. A 12.7mm carb is big enough to run a 35cc engine or even some 50cc engines too. So I rummaged around and found a WT-520 carb with a 9.53mm venturi and I put it on the engine. Now the engine ran great, easy to adjust, throttle response good, nice RPMs and I could lean it out good too.
At that point I didn't see any reason to not use the engine as it was performing good now.
Posted by earlwb |
Sep 03, 2012 @ 08:12 AM | 11,568 Views
I had put my second NGH 9cc engine in a Great Planes Escapade 40 size plane.
The only modification done to the engine was to use 8x32 fittings for the crankcase to fuel pump diaphragm and 1/8 inch Tygon fuel tubing instead of the smaller 3/32 inch fuel tubing. Previously I showed a video clip of how well the engine ran like that so I was motivated to fly the engine to be sure it was working in the air too.
Also the carb should have the low speed needle set to about 6 turns out and the high speed needle set to about 1 and a half turns out. The LSN setting on my case was about right and I didn't need to change it from 6 turns out. Also the carb does spit fuel out, so it is not running too rich, it is just the nature of the beast, so to speak.