Dear Dave,
Kindly request assistance.Idles 2000Rpm Full power 10,800.no probems. Mid Range Starts running Rough after 10-20secs then dies. Almost Impossible to restart after this death. Have to wait about 10Mins. All settings tried on regulator eventualy back to flush to no avail . Engine is new has been run 6x 8mins.Check valve good,fuel filters fine, YS F plug good, Tank holds pressure for two hours after shut down. Using 15%Nitro 18% Synthetic 2% Castor. Operating Altitude in Petoria 5,500 Feet ASL . Temperature 70degF. Set Valve clearance 0.0015 inch (cold)
Please Help ?
Regards
Dave

Valve clearance is too tight. Open it up to .003". What size prop? With 15% you better not try to run more than about an 11x7. What glo plug?

Dear Dave,
I am Indeed honoured to Have such a Prompt Reply from the YS Prof !! APC 12-7, OS Type F Plug. Would these present valve clearances be the cause of almost impossible starting after engine has warmed up a little? Because when I hand turn the engine slowly to feel the kick, its just not there when she is warm.
Greetings From Sunny South Africa
Dave Black
PS. With Your Proffesional help I WILL master this engine. I bought on Advice that it was the finest small 4 Stroke in the world.

My YS .63 which is new seems to have this very same problem too. I will be interested in what Dave says could possibly cause this.

The valves are too tight. Sport 10 try re-adjusting yours.

Remember, if you aren't going to run the recommended 20% nitro fuel, at least reduce the prop load to compensate.

Dear Dave,
Taking the 747 to London tonight Hopefully the 4 Rolls Royces are set right....returning Sunday and will continue the struggle. Please advise if valve clearance too tight could cause difficult starting when engine warm?

It will if the valves hang open. How's the hot compression on this thing?

Hot Compression good. The Latest diagnostic:
When throttle is Opened anywhere between above idle to aprox halfway. it is noted that the blue fuel pipe from rsg to carb draws air then fuel then air then fuel continuously causing rpm fluctuation and when it draws a bit too much air it dies.Idle perfect full throttle perfect. No air present in supply line. This seems to point to the REGULATOR. Checked Reg Diaphram will mag glass dont see any holes, cleaned and reasembled with notch facing foward towards prop.All fuel lines replaced would seem that reg not sealing properly. Plase help Dave

Judging from that I would say that the reg housing itself is bad.

To Dave Shadel,
Thanks Dave, Will take engine back to England next week with this thread and will let you know what happens early next month , Regards
Dave Black.