earlwb's blog archive for August, 2012 - RC Groups
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Archive for August, 2012
Posted by earlwb | Aug 05, 2012 @ 10:49 PM | 27,933 Views
I had modified my NGH 9cc engine to use a Walbro carburetor. After getting it all setup I do realize I had several other ways I could have done it. But I wasn't sure what the effects would be or how successful it might be either. So I sort of took a more simple approach to it. This carb I used is a WT-298-1 carb and it has a 7.14mm intake venturi in it, but the carb has no choke, so you have a harder time warming up the engine before it runs good like that. There are several other carb models that ought to work fine as well, and also some carbs with about a 8mm venturi size that might maybe work better too, but I haven't tried one myself.

All in all after getting the carb dialed in some, the engine was running pretty good, much better than how it behaved with the OEM two piece carb and pump/regulator. The Walbro carb exhibited no vibration sensitivity and was reasonably linear in its throttle opening from low to high speed. Now if you rapidly chopped the throttle from WOT to low, the engine had a tendency to flood out and die, but if you more gradually went to low throttle it allowed the regulator to work better and the engine would idle fine then. The engine temperatures I measured were about what measured with the stock unmodified NGH 9cc engine. I don't think it was running much more hot in temperature as the measurements were around the same at 376 degrees on the ground in a static engine run scenario. I assume the engine would run more cool up in the air flying around...Continue Reading