stays at full throttle after servo returns to idle position along with things that don't make sense to me.

[bownsy]

I recently broke the engine in, and today I was going to try to tune it. It was cool out and did not want to tune it till the temp came up so I ran a tank of fuel through it. Lots of blue smoke on the high end, refilled the tank and was going to run it a few minutes and adjust it, I bumped full throttle and there it stayed went up a big dirt pile and calmed down, Leaned it out about 5 minutes, same thing stayed at full throttle for a moment and calmed down. This happened three times, during this time I leaned it out about 15 minutes total. I filled the tank up a third time but this time but put it on a bench bumped the throttle to about half for a while and it was fine, I went to about 3/4 throttle a few times and it stuck so I hit the brakes and it died. The throttle servo returned to the idle position. I also noticed a lot of air bubbles while It was on the bench in front of me. It seemed like my steering servo was sluggish a few times. But I worked the servos with the motor of watching them for at least 5 minutes with no interruptions. Anybody have any ideas? I would say servo issues but I seen it move back to the idle position, but I also think my steering was being wonky. Its a Kyosho neo, it was a cool day so even hitting 200 degrees was a challenge.

 

[tntpoof]

did you pre heat cylinder at all? have you bound radio to rx?

 

[Lukedavis]

did you pre heat cylinder at all? have you bound radio to rx?

I think if he didn’t bind it it wouldn’t have driven at all let alone steer. I guess he could try and re bind the radio to the rc though. I don’t think that the cylinder has anything to do with the runaways.

I recently broke the engine in, and today I was going to try to tune it. It was cool out and did not want to tune it till the temp came up so I ran a tank of fuel through it. Lots of blue smoke on the high end, refilled the tank and was going to run it a few minutes and adjust it, I bumped full throttle and there it stayed went up a big dirt pile and calmed down, Leaned it out about 5 minutes, same thing stayed at full throttle for a moment and calmed down. This happened three times, during this time I leaned it out about 15 minutes total. I filled the tank up a third time but this time but put it on a bench bumped the throttle to about half for a while and it was fine, I went to about 3/4 throttle a few times and it stuck so I hit the brakes and it died. The throttle servo returned to the idle position. I also noticed a lot of air bubbles while It was on the bench in front of me. It seemed like my steering servo was sluggish a few times. But I worked the servos with the motor of watching them for at least 5 minutes with no interruptions. Anybody have any ideas? I would say servo issues but I seen it move back to the idle position, but I also think my steering was being wonky. Its a Kyosho neo, it was a cool day so even hitting 200 degrees was a challenge.

Does the receiver have a Lipo to power it or AA/AAA batteries?

 

[bownsy]

I think if he didn’t bind it it wouldn’t have driven at all let alone steer. I guess he could try and re bind the radio to the rc though. I don’t think that the cylinder has anything to do with the runaways.

Does the receiver have a Lipo to power it or AA/AAA batteries?

AA. I have a nimh pack I going to change it to, I just need to get the right adapter to charge it. I checked the batteries with an old tester we used for airplanes. it showed 5.4+v with a 500ma load. I will try rebinding it. We warmed the engines to about 80 degrees. Thanks for the help

 

[Lukedavis]

AA. I have a nimh pack I going to change it to, I just need to get the right adapter to charge it. I checked the batteries with an old tester we used for airplanes. it showed 5.4+v with a 500ma load. I will try rebinding it. We warmed the engines to about 80 degrees. Thanks for the help

Yeah. Th AAs usually have a tendency to cause a runaway. Idk why they do it though.

 

[bownsy]

did you pre heat cylinder at all? have you bound radio to rx?

Pre heated a little, around 80 degrees, didn't run hard until temps came up. I will try to rebind it. Thanks for the advice.

Yeah. Th AAs usually have a tendency to cause a runaway. Idk why they do it though.

I will get that changed tonight, thanks.

 

[tudordewolf]

Yeah. Th AAs usually have a tendency to cause a runaway. Idk why they do it though.

Alkaline voltage drop under load is pretty severe (see linked datasheet), and modern servos have higher stall currents - except for disposable lithium-manganese AA's which cost as much as a rechargeable receiver pack anyway, you're likely to see brownouts with 2 servos trying to draw 1-2 amps each from AA cells rated for 1A max. Their capacity almost plummets under high-drain conditions, to less than half what it would be drawn slowly.

Nickel batteries do this too, but to a lesser degree, and can handle much higher drain.

Lithium batteries experience voltage drop too, but still deliver 90%+ of their stored mah even under very high drain conditions, which is one of their big advantages.

 

[gandalfnz]

I have been using AA's Panasonic Eneloops NiMh batteries and have never had an issue, as long as batt holder is good.

Check your throttle linkage before starting the motor, make sure there is no binding and that it moves smoothly and returns to idle gap when in neutral, there MUST not be any movement in the carb slide when you apply brakes.
Also, just because you press 1/2 or 3/4 on your remote, does not mean your carb slide is doing the same.

Good luck!

 

[bownsy]

Thank you all for the advice, I will change to the rechargeable battery pack 2000mah nimh tomorrow, check and remove linkage and make sure there is no binding on the carb and look for any bad connections or pinched wires.

 

[bownsy]

Checked everything out and found where the on/off switch connects to the receiver was really loose, does not fit in very well, fixed that, but what I think was causing the problem was when I was checking the 4AA battery pack as a whole it was showing just over 5v when I checked the batteries individually one was almost completely dead the other three were not much better. I Put in the nimh pack, a MP9 air filter upgrade and got my Bones Brew fuel in so as soon as the rain is done time to tune. Thank you all for your help.