Guy's this May be a topic that has been discussed already but just know that it has been and is an issue for some. I have heard of several people experiencing troubles regarding there Regulated OS105's going Lean on them. Well i actually had this happen last weekend. I currently am running V curves in my #1 N7. With that being said, this machine has been running flawlessly on CP 15%. With the temperature increases in Georgia last weekend I backed the needles (1) click each on low and mid (Ran/Pulled strong) 2ND to the last flight I noticed the motor hunting regarding Mixture (Rich/Lean) I brought it back in and rich ended it just 1 click each and looked for any signs that could attribute to this sparattic condition.(even checked the cooling fan " Habit") now I'm running the stock clunk which normally I don't do, however I haven't changed it. With 1.25 gallons of fuel run through this machine, all is in order.
I removed the regulator an completely disassembled it, nothing out of order there (diaphragm is intact and all parts clean and in order) I have a theory of what may be going on based on my experience with Standard carbs and Pressure Carbs, I understand them very well, and the one thing that I question is the "Spring Tension" under the needle Arm. I removed mine and cut 1 coil out of it and reinstalled with the (cut side) seated in the recess of the regulator body. In doing this I decreased the tension which allows the diaphragm the ability to depress the arm with less resistance to allow more fuel. This is a method that is common on Jet Ski carbs when setting pop off pressure , when you can't find the correct spring to set it. I had the chance to fly it today and reset my needles to where they were and had great results. I'm not saying this is everyone's problem, I advise you to run a proffered fuel clunk, check your clunk line, and most of all when you remove the pressure line from your tank ( Make sure you have pressure)!!! If you don't, I suggest you source other methods of diagnosis like your check valve!!! But for those that have carefully looked there machine over and are still stumped, this may be the solution. Feel free to Email me if you have questions hwood3160@yahoo.com , it is easier for me to respond this way and even more willing to talk on the phone, Good luck and don't give up on your Regulated OS just yet. I will say that there is no set formula for figuring out how many coils to cut, and that if your comfortable knowing that you have exhausted all other avenues and are willing to try this, I advise to make small adjustments and test accordingly. Don't get carried away and cut to much, I'm not even sure you can buy a spring?? Again this worked for me, Variances in field elevations/altitude may effect your results.
Best Regards,
Kevin
