kenh3497

I don't usually pay much attention to new engines but looking for some info on the YS site I see they have a "new" 80 4C available now. It seems YS can't make up it's mind what it wants to settle on for "standard" displacements. It seems they have hit all the numbers. 53,63,70,80,91,110,115,120,140,etc

So does anybody have any experience with the 80? I guess the upside is it bolts into the same mount as the 63 & 70.

Ken

Four Stroker

I would like to know how you stroke an engine 3 mm and fit the same mount and have the same height - as stated in the instructions that I downloaded. Of course the instructions are just a bad cut and paste of the 70. In particular, same mounting means not only same bolt pattern BUT also same crankcase width.

I someone gets one, would you actually measure the crankcase width at the mount and the height ?

There ain't 1.5 mm more in the case for the bottom of the rod. Maybe they reduced the pin diameter ? Rod end ?

Four Stroker

I have one of these now. It is indeed the same outside dimensions and mounting as the 53,63,70. Have not run it yet.

The main surprise is that the carburetor throttle barrel now has no tapered metering slot at all. There is simply a new tiny hole drilled into the intake side. There is an evolution here from fancy multiport carb. to tapered slot only to now just a hole. This reminds me of the old days two stroke air bleed carbs.

Different parts are crankcase and cylinder and rod for stroking. Smaller diameter crank pin and rod end. And different throttle barrel and carb. casting.

Will run when the weather gets better.

Jim Schwagle

My Feedback: (1)

On my first bench run,1/2 tank of fuel into the run, I got 9800 on an APC 13-9. 20/20 Powermaster fuel. The only prop I have used and the only run.

Four Stroker

How did the new carburetor work ?

Jim Schwagle

My Feedback: (1)

No adjustments yet, other than to make sure it was rich using the High Speed needle. However, it seemed fine to fly with after only one tank. The idle is ok, below 2300, and I haven't touched the low speed, so.....

Four Stroker

Tried out my engine this weekend. The new carburetor on mine ran at about 3/4 turn open ! The old 70 carbs ran at about 1 & 3/4. Ran 5 tanks through it. It is about right now. Needs some slight tuning still.

Four Stroker

I have maybe a dozen tanks through the 80 now. Final needle is about 7/8 open. Air bleed screw is 2 & 1/4 out - but not critical. Runs fine. 30% Rotor Rage Heli fuel. This fuel produces much less carbon than Cool Power heli fuel or Wildcat heli fuel. Don't know why ?

the Wasp

My Feedback: (1)

Guys, I have been wanting another 4 Stroker, can we get an update on RPM numbers and Prop sizes

thanks
Jim

Four Stroker

It's just a 70 stroked 3 mm. Has some improvements. Carb works very well. Oil groove on valve lifters. Better gasket material. I am surprised nobody has a YouTube test up ? The 70 is now 6 years old. The new 80 is very nice and easy to handle. I use Rotor Rage 30% heli. Not the same piston as 70 although the instructions say so. Does fit the same mount as 70.

Yamada is continuously improving the engines. This is the latest starting from the 53. It will do very well if you do not use after run oil that is not specifically intended for silicone parts and says so on the label. Most RC hobby after run oils will eat silicone as will Marvel Mystery oil, air tool oil, Mobil 1 ATF, Mobil 1 oil, etc. I have actually tested this long term. There are famous pilots that will swear to the contrary.

MrShoes

My Feedback: (15)

Four Stroker,

You said the crank pin and rod end diameter is "smaller". Does it appear that is only thing done to increase the stroke of the fz80? Reducing the crank pin diameter by about 3mm seems like a lot. I bet they also milled away material from inside the crankcase to form a path for the connection rod end. I've seen this when YS maintained the same mounting dimensions going from the YS 120 all the way to the DZ185. Thanks

Four Stroker

The pin and rod end are smaller. Has to a be moved out radially 1.5 mm to stroke 3 mm. There is not any more room in the case to mill out ! Download the instructions from http://www.ysengines.us All part with a 7xxx are new. The piston is new as well with virtually no skirts. Same number OR wrong number OR will also fit 70 ?

I don't get to this site very often. Engine is running great and much cooler than the 70. May be I am running rich but have the same power.

MrShoes

My Feedback: (15)

Probably too rich. It should turn ~ 700 rpm more than 70s on same prop.

Four Stroker

Mine is in a TREX 600N.

BartekSz

Hello what is the rpm or propeller diffrence between YS FZ80 and YS DZ70?

Four Stroker

"Probably too rich. It should turn ~ 700 rpm more than 70s on same prop."

BartekSz

But i asked about DZ70 not FZ70s

Four Stroker

OK sorry. I don't expect there to actually be much difference between the two 70's. But I don't have a DZ 70.

BernardW

I've heard this and been wondering, what's the right oil to use then? I'd be grateful if you could recommend an ARO that won't attack the silicon in my FZ-91AC. I just got this mint-in-box, never run or sold before, and that means it must have sat in a box somewhere for at least 10 years. I would also appreciate if anyone could tell me what to expect from that - will the seals/diaphragm deteriorate over time, when the engine has literally never even come out of the original plastic bag? Will it likely be a) OK, normal, fine, no issues b) fine but for reduced time before silicon-based parts need changing, or c) the silicon parts probably need replacing already due to age. Again, I emphasize it's never been sold or run, and definitely nobody's ever put fuel or any type of oil in it, it's literally straight off the shelf as if it were still new stock... it is really, it's just been there all these years. By the way, when exactly did production for these cease and is there anything on the engine, box or documents to tell me when it was manufactured?
Thanks in advance.

Four Stroker

I use Performance Specialities Ultra Oil that Dave Shadel used to sell. I think Dave retired ?

But this one is probably good: https://www.centralhobbies.com/cat3....=28&subcat=178

Hey these guys still sell it: http://www.bj-model-engines.com/UltraOil.html

Back to your other questions. If the engine turns over smoothly it is probably fine. The silicone parts are probably good forever in storage. Depending on how old this engine actually is it may need a new diaphragm in the regulator. YS went through 3 different materials that I know of.

BernardW

Thanks very much, I appreciate the info. Someone told me to avoid ARO's based on ordinary mineral oils but without knowing my way around the market, I really wouldn't have known what to go for.

I think this must have been one of the last of the FZ-91's supplied for retail sale. The store operator said he thought he'd had it in stock for maybe 3 years but that seems odd to me, unless the wholesaler had it in their warehouse for 7 or 8. AFAIK it's been about 10 or 12 years since these were last in production. He told me he can definitely supply spare seals, diaphragms and so on so I thought it would be a good idea to order at least 1 or 2 sets in now before they're all gone, because if/when the day comes in several years when I need them, it's only going to get harder with time to track them down. I don't think it's worth stripping it down to check all these just in case, because as stated this engine has never been fuelled or run. Yes, it turns over no problem if I fit a prop so I can turn it by hand, there's no roughness and there's plenty of compression. I'm not noticing any particular problems. As far as I can tell there's no reason to think it's anything other than mint and absolutely as new. Once again it's a lucky find. I got it for just under half the original sticker price, so it was $AU 300 (about $US 225) and for this engine in this condition, I'd have to think that's about as good as it's going to get. I doubt I'd find another one like it.
Thanks for the advice.

Four Stroker

http://www.yspower.co.jp/en/

Ask Yamada about the latest and greatest diaphragm for this engine. Probably get the part number by downloading the manual. The original rubberized cloth was crap. The white plastic was OK. I think they were silicone at the end. BUT your regulator parts may require the same type as installed ? The last one I looked at had the white plastic. If so get many. They are cheap.

BernardW

The guy at the store said somehow he knew it was the silicone type, which sounds like it's the one you want. But if I'm going to be ordering more then I guess they'll be silicone type? Since they don't cost much I'll definitely take your advice and lay in a big stock.

Four Stroker

Well here I can get Rotor Rage, Curtis Youngblood, and Cool Power fuel in 30%. The Rotor Rage is the best BECAUSE it does not carbon up the valves nearly as much as Cool Power AND it has a thinner oil that does not accumulate in the case and put out the idle like CY. Might get a spare ring. All of the gaskets and seals in the engine will cost about what you paid for it ! So don't go crazy. I would just get a few spare diaphragms, a ring, and a paper gasket set.

kenh3497

My 91 uses a mylar diaphragm. As far as I know there is no silicone in the engine that will come in contact with any oil. IMO for the 91AC any oil will work.