ORIGINAL: tele1974
Tuning:
I know their is plenty of information about walbro tuning on the internet. But, I was wondering if you guys would give your techniques for the Syssa and how you meet the low and high needle in the middle per se'. That might be a good addition to the recipe.
Well, as it comes set up from the factory, the carb will work okay for small props on muffler. That is the intended purpose of the engine after all...a great little sport engine.
The first thing to do if you run a pipe is to richen the HS needle to 2 1/16 open; LS speed needle open to 1 1/4 or just a hair more.
After full break in, HS needle seems happiest at exactly 2 turns open and LS needle at 1 3/16 open or very slightly leaner. It's working great at these settings. I have two SAPs and they are set-up practically identically, on pipe....except one is turning a 17x12 APC and the other a 16x12 APC. Both run fine at these carb settings
Almost forgot to mention that the engine has got to have lots of cooling air velocity around the head. I had to baffle the chin cowl of my new plane leaving about 3/16" air gap around te head. Before baffling the engine tended to sag on extended vertical stuff, loaded with the 16x12. After baffling, it ran super in the hottest days last Summer