ryobi 31 rpm
04-09-2014, 10:02 AM
#1
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ryobi 31 rpm
how do I get the rpm down to about 7500rpm? this is what I have done. I put A MT 35 carb on it, apc 18/8 prop electronic ignition set at 28 degrees the max rpm with this set up is 8600 rpm. I was thinking of changing the prop to a 20/8 or maybe
18/10 apc The airplane is A spad stik I don't need speed I know the static rpm should be about 7500 on the ground. I could epa to adjust it down at full throttle after the carb is adjusted. what would you do thanks michael
18/10 apc The airplane is A spad stik I don't need speed I know the static rpm should be about 7500 on the ground. I could epa to adjust it down at full throttle after the carb is adjusted. what would you do thanks michael
04-09-2014, 11:35 AM
#2
A two inch larger prop is a LOT more load, so that would probably do it. Are you sure your tach is correct though? 8600 on an 18 x 8 prop is extraordinary for a Ryobi 31. I have a hopped up one that will turn those rpms on an 18 x 6, but not an 18 x 8.
Also, the APC props generally don't load the engine as much as other props, especially if it is that funny pointed tip APC that you are using. Zoar props are quite good and load the engine more than most other types.
In the end, setting a rev limit by limiting the throttle might work, or it might still try to overspeed in the air due to the prop unloading.
AV8TOR
Also, the APC props generally don't load the engine as much as other props, especially if it is that funny pointed tip APC that you are using. Zoar props are quite good and load the engine more than most other types.
In the end, setting a rev limit by limiting the throttle might work, or it might still try to overspeed in the air due to the prop unloading.
AV8TOR
04-09-2014, 01:43 PM
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I made a mistake the the prop is a 18/6w and its a new tach iam just worried that the connecting rod will fail with that high of rpms I am going to try an 18/8 to see if the rpm comes down would the carb off a 30cc engine cause to much rpm? reason I ask is I see other people using stock carbs and their rpm numbers are 6600-6800 using a 18/8. Its got to be the prop I am using It doesn't have a name on it just the size and pitch it is grey in color and narrow at the tips I am used to using master airscrews classic props
04-09-2014, 03:27 PM
#4
Try an 18 x 8 Zoar on it if you can. That will probably bring the rpms down. As you know, 7500 static is the basic safe rule of thumb for this engine. I wouldn't try to de-tune it and lose power, you can never have too much power! (See my "signature" below.) I would just prop it up until the rpms are safe, and then go fly and enjoy the thrust/power. If it flies faster than you like with the 18 x 8, then go to a 20 x 6 or 8 to trade the speed for thrust/acceleration.
AV8TOR
AV8TOR
