ORIGINAL: aerobear
Don't give up. I have an identical setup that runs great so I am guessing you have some yet undiscovered problem. Mine had an APC 16x8 with OS F plug.
The Jett webpage claims 9600 rpm with the APC 16x8. I got slightly more than that. I don't remember what the rpm with the stock parts was but the Jett setup gave a healthy increase in power with very good behavior throughout the rpm range.
Have you tried a batch of fresh fuel?
Has the engine been run very lean? I saw one of these that had been run so lean the top of the cylinder liner had turned blue.
What tach are you using? The cheap hobby tachs we use can give unreliable readings if the lighting conditions are not optimal.
The fuel is fresh, bought about a month ago, and the engine has been overheated to the point that I accidentally touched my forearm to the head and received a nice striped burn. The overheating happened before I got the bubbeless tank. The previous tank would be good if kept full, but once it got to about 3/4 full, the bubbles would create a very lean condition.
I should take the head off and check the condition, shouldn't I?
Tach is a hangar 9.
ORIGINAL: NikolayTT
Anyway with this 15% nitro in the "blood", this ST is maybe not in the best "mood"...
Should I get some lower nitro content?
ORIGINAL: Sport_Pilot
I would consider an Enya #4, OS A5, or Fox #8.
Thanks for the tip.