ZDZ Super 80 idle question

[bmoranx]

All - my ZDZ 80RVJ runs well and transitions quickly and cleanly but I have one problem.... The engine idles a bit higher than I'd like. I can run it around 1800-1900 rpm with reliable and consistent results. If can slow it down to 1500 where I'd like, it will idle all day, unless the throttle is chopped too quickly. Example, idle to full throttle good. Full throttle to idle slowly, good. Full throttle to idle quickly (chopping) the idle will drop very low or stall, if it keeps chugging after the throttle is chopped, it will almost die and then slowly speed up to the desired idle. Everything else seems fine. The engine has abit over 5 gallons through it so far.

Additional info...I am running Mobile1 synthetic at 40:1 and a Vess 27A prop. This engine also shows the same symptoms when running my PT Models and Mejzlik 26X10 props. The 26" props turn up around 6500-6600 static, the Vess 27A turns 6100 static but pulls like a freight train. Any thoughts? Could a fat high speed needle cause this?

thanx/Bruce

[scoubidou]

I have two super ZDZ80 RVJ and both do the same thing. Can not idle below 1500-1600RPM with Biela 26x10 6300 RPM, or Mejzlick 26x10 6700 RPM.

Powerful engines and transition is great except they are a pain to start and no useful idle to fly IMAC for the spins/stall entry.

Did you post your question in ZDZ forum?
http://www.rcuniverse.com/forum/forumid_204/tt.htm

Daniel

[bmoranx]

Daniel, thanks for the info... I had hoped to hear otherwise but it is what it is.. As for the ZDZ forum, I didn't even realize there was a ZDZ specific forum but I will post there..

bruce

[tec]

	Quote: Originally Posted by scoubidou
	I have two super ZDZ80 RVJ and both do the same thing. Can not idle below 1500-1600RPM with Biela 26x10 6300 RPM, or Mejzlick 26x10 6700 RPM. Powerful engines and transition is great except they are a pain to start and no useful idle to fly IMAC for the spins/stall entry. Did you post your question in ZDZ forum? http://www.rcuniverse.com/forum/forumid_204/tt.htm Daniel

Mine super 80 starts on the first flip 95% of the time after the 5/5/1 starting sequance. Mine also idles smooth and slow, I guess mine has alot more time than yours? (about 50+ gallons) Belray 50-1 and a Vess 26A. Hovers my 26lb SD 260 at 1/4 throttle on a canister.

[scoubidou]

Do you have the new orange ignition? It supposes to be better than first generation. We are 4 pilots in my club and nobody can start their engines with 5/5/1 starting. Mine needs 30 flips full choke, full throttle to fire.
Daniel

[AHP]

What throttle servo are you using? If it wants to die when quickly chopping the throttle your servo could be slightly overshooting its end point. I've had that happen with worn and/or cheapo servos. As the pots start to deteriorate, the servo will start to get less precise. Just something to think about.

A buddy of mine has a Super 80 and it has a nice reliable low idle. My standard 80 will idle way down as well.

[Neogenesis]

	Quote: Originally Posted by scoubidou
	Do you have the new orange ignition? It supposes to be better than first generation. We are 4 pilots in my club and nobody can start their engines with 5/5/1 starting. Mine needs 30 flips full choke, full throttle to fire. Daniel

There is no way you should need 30+ flips to start. I would be calling RcShowcase and getting some answers. The first one I had was about 10 flip choke till pop and about 5 with choke off till running for the first run of the day. After that it usually started on the first flip for the rest of the day. That one however put a bolt through the bottom of the crankcase which RcShowcase promptly took care of. The new one they sent me doesn't have enough time to accurately judge, but so far it's not as enjoyable as the first.

Have you called Mike and if so what was his response?



Neo

[scoubidou]

	Quote:
	Have you called Mike and if so what was his response?

His response was too lean on low needle valve....
My answer after 30 gallons of gas with 3 super ZDZ80 is wathever the low needle valve position, it does the same thing. In fact i had 3 super ZDZ80 on my hand and the first one, the engine head cracked and broke by itself after 15 gallons, without overheating issue. I am using JR821 digital servo on the throtle. RCShowcase replaced the engine under garanty. The customer service is first class but this engine is still a pain to start. The first super ZDZ 80 hot restart needed only one flip without choke, while the two others need 3 or 4 flips on the choke for the hot restart.

[bmoranx]

	Quote: Originally Posted by tec
	Mine super 80 starts on the first flip 95% of the time after the 5/5/1 starting sequance. Mine also idles smooth and slow, I guess mine has alot more time than yours? (about 50+ gallons) Belray 50-1 and a Vess 26A. Hovers my 26lb SD 260 at 1/4 throttle on a canister.

Tec - is 50:1 safe to run in the Super 80? I have been running 32:1 and would love to move to 50:1. ZDZ says 40:1 may but they are an engine manufacturer and probably want error on the safe side to avoid warranty issues. Funny though, i wonder why there is such a difference in oul mix ratios among the engine manufactures...

[tec]

	Quote: Originally Posted by bmoranx
	Tec - is 50:1 safe to run in the Super 80? I have been running 32:1 and would love to move to 50:1. ZDZ says 40:1 may but they are an engine manufacturer and probably want error on the safe side to avoid warranty issues. Funny though, i wonder why there is such a difference in oul mix ratios among the engine manufactures...

I have not had any problems with mine.

[AHP]

I think a big part of the reasoning for ZDZ recommending a higher oil content is due to the rotary disk as opposed to a reed block intake design. I've always run 40:1 in my ZDZ's with great success. Regardless, I still can't believe any manufacturer would recommend a 100:1 mixture but that's beside the point...

[scoubidou]

We have only 3 ways to cool our gas engines:
1) run rich
2) add baffles in the cowl
3) use 32:1 or 40: oil mix.
Remove one or of all of them and you're in troubles.
Use Belray H1R 40:1 in mines. DA, ZDZs
Daniel