Dar,

No, that rpm sounded too high. Here is an excerpt from their website:

Displacement: 7.98 ccm ~ .49 cu in.
Bore: 22mm
Stroke:21mm
H.P.: 1.54
Rpm: 17,000
Weight: 13.40 oz.

*Rotation feature - choose side or rear exhaust configuration before break-in.
*Instantaneous throttle response
*Excellent idle, crisp transition
*15,500+ rpm’s with 12.25 x 3.75 prop
*Prop Choice: 12.25 x 3.75, 11x5 11x6 for "fun fly"
*11x6, 9x8, 10x7,10x8 for speed.

I certainly did not think this would produce more hp than a Jett.
Actually, I should appologize for getting us onto rpm numbers. My current cheapo chinese motor will spin this prop more than fast enough, flight ready rich at 13,500 according to my cheap uncalibrated Hobbico tachometer. Regardless of the actual rpms, it will pull my plane out of sight. It just wont throttle the way I want it to. I cannot trust it's midrange, it gets too rich and will flame out if allowed to run at low to mid throttle settings for any length of time.





f2racer,
Thanks for the rpm numbers that you are getting. Those sound more in line with what I was thinking. When you say the throttle response is better with an 11.5x4, does that mean the response is not good with the 12.25x3.75? Also, do you notice any mixture issues at low to upper-mid throttle with these engines?



Bob,

Thank you for joining this. I am not quite ready to purchase a Jett, but plan to in the future. Something you said in your thread was interesting, you mentioned the SJ-50 would get rich at mid throttle. I am ignorant about such things, but does that mean that my current cheap motor may not get rich at mid throttle if I change it's application and use it with smaller higher revving props?