Telemaster Sales UK

I strongly suspect that the engines will be interchangeable. Most engine manufacturers produced engines which matched the OS mountings.

sailr

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Thanks!

dopf

Hi guys,
just found this huge thread and maybe here's where I can get a tip for a weird problem I have with an Enya 4C

I bought a used 60-4C and mounted it on a test stand. Plug is an OS type F, fuel is fresh with 10% nitro and 15% synthetic (Molsyn 150 K), prop is a master airscrew 12x6 three blade, the mini exhaust with pressure tap is fitted and tank midline is roughly on same height as the carb. I'm getting 9,500 rpm at WOT and good idling between 2,500 - 2,700. Do these rpms sound in the right range?

Now the weird thing is what happens when I go from WOT to idle:
First the rpms drop below the set idle speed, approx to 2,000 - 2,300 very briefly, maybe a second but it sounds like it's about to die/stop. Then the engine ramps up to a higher idle of roughly 2,800 - 3,000 rpm for 5-15 seconds. Finally it then drops back to the original idle speed.

i've tried plenty of adjustments on the HSN as well as air bleed screw but the issue persists. What's noteworthy is that the HSN is only 0.8 - 1 turn open for the (almost) peak rpm above, the air bleed is 2/3 open which seems normal. Now I'm also lucky to have an Enya 80-4C and 90-4C both of which never showed the same weird behaviour. I've checked the o-ring between carb and intake to see if the engine gets air where it's not supposed to and added some fuel tubing at the HSN insert.

Any hints what this could be?

Thank you!

1QwkSport2.5r

Make sure the metering groove in the barrel is absolutely flawlessly clean. If there is any crud in it, it will affect the fuel mixture from idle up to about 3/4 throttle.

Also, without an extra head shim fitted, the engine might be a bit cantankerous on 10% nitro or higher. My 60-4C is a bit finicky with nitro. 5% nitro is fine, 10% nitro is okay if you keep it 500+rpm rich of peak. I could add a head shim to use more nitro, but it doesn’t turn much better rpm, so I don’t bother. 5% nitro works perfectly.

dopf

Thanks for the quick reply!

The only other fuel have around is FAI 80/20 at the moment, would that be worth trying?

Not sure which metering groove you're referring to?

Cheers!

1QwkSport2.5r

If you have an Enya Airbleed carb (G type), then you actually have a metered airbleed carb. Pull the barrel out of the carb body and look at the fuel fitting/main needle side of the barrel. You’ll see two pointed grooves pointing in either direction around the barrel with a hole between them. That pointy groove is what meters fuel at idle up through most of the midrange. If there is any crud stuck in the groove, it will run lean and/or erratically or both.

paulinfrance

For more information have a look at this,
Enya 60-4C (1)

1QwkSport2.5r

Here is the metering groove I was talking about. This is from my early 60-4C.

dopf

Thanks a lot 1QwkSport2.5r & Paul!

I've cleaned the groove and entire carb with brake cleaner & and exacto knife. On the test run the engine ran overall cleaner, but the behaviour with initial drop and then increased idle speed after WOT persisted. However I also did a test without the muffler and pressure tap and this seems to resolve the issue. Also the engine sounds amazing with just the header pipe
Changed the prop to a MA 13x6 two blade and got up to 9,800 rpm and 2,200 idle this way.

Just a guess, but would it be possible that the muffler pressurizes the tank so much during WOT that it leads to providing excess pressure & fuel when it's back to idle and therefore increased rpm for 5-10 seconds?

Cheers!

1QwkSport2.5r

My 60-4C didn’t come with a muffler, so I just run the header and no muffler pressure. They don’t need muffler pressure. Also, the two-step idle is pretty normal for Enyas. The 60-4C and 80-4C like a rich idle. They will burble a little bit. Totally normal.

Here is my 60-4C idling. You can hear the two-step idle in this video a little bit. It was idling a bit fast, it it’s still there. Completely normal.

1967brutus

Yes... Coming down from WOT, it takes 1~1,5 seconds for the pressure in the tank to bleed off, while at that exact moment (RPM still high but falling, and throttle closed) the suction is temporarily stronger. That is enough to cause a rich period that can last up to 5 seconds.
That engine was not designed to run muffler pressure and won't benefit from it.

1QwkSport2.5r

4-strokes just in general don’t need muffler pressure. The negative pressure in the intake is much greater when the intake valve opens, so fuel draw is often very very good.

1967brutus

Don't know if I agree with that... An OS 90 surpass in any case does need it, as do the chinese copies, and it all has IMHO to do with carb throat diameter, because the pre-surpass engines did not need or have it, and they had smaller carbs.
I think a blanket statement ("in general") cannot be made...

1QwkSport2.5r

You don’t have to agree. My experience has been it isn’t needed. The biggest 4-stroke i have is a 1.20, and it doesn’t need pressure; though I do use it on that engine because I don’t have a screw to plug the hole where the muffler tap is. It’s a weird metric thread pitch that isn’t worth trying to source.

Telemaster Sales UK

Laser four-strokes are built without a pressure tapping on their silencers.

1QwkSport2.5r

I will say muffler pressure does even out the mixture below half tank when the e fine needs to “work” a little harder to draw fuel. Without pressure, you just have to set the needle a little fatter to compensate.

ev2driver

Hello folks, just want to share my recent experience with a Enya 53-4c I bought used.
I stripped it down to clean/inspect it : over all the engine was very clean with apparently low use and good compression
After reassembly the engine wouldn't spin more than 9300 rpm with an APC 11x7...too low to fly safely the Kyosho Focke Wulf .50 where it was placed. . So I double check for timing proper assembly, but the notch alignment was ok.
Meanwhile i found an bought an new in box 53-4c just in case my effort to regain the usual power were unsuccessful...

So I dismantled both valve covers to inspect the timing back to back... the used engine had inlet vale opening too late (e.g nearly at TDC, instead of 20 before TDC) while the new one had it opening correctly with an overall dwell of 40 degrees between valves
The used engine had the inlet cam gear timing notch wrongly punched (see the red circle in the photo where actual punch is, compared to where it should had been, green dot line)!!!
After I restored the cam timing, power came back in.
So if you have any doubts you must measure actual cam timing...

Paolo

https://drive.google.com/file/d/1ta9...ew?usp=sharing

TimC

That was some good detective work ev2driver.

GallopingGhostler

Agree with the others, good detective work and restoring another Enya 4-stroke to its usefulness.

TimC

I wonder how many engines were turned out like that?

1QwkSport2.5r

Not many; I have never heard of this problem in nearly 20 years of having Enya 4C engines. I suspect they used a cam from a different engine in the used engine. They don’t all have the same valve timing.

Jesse Open

Or, perhaps someone simply pr ic k punched the mark in the wrong spot. These were never made in huge numbers. No doubt a lot of hand work along the way. Much stranger things have happened.

dopf

Hi Enya-nites,

I've recently cleaned and refurbed an Enya 90-4C. Now on the bench it turns a 14x6 Master Airscrew Scimitar at 9,700 peak or 9,400 slightly on the rich in side. That seems slightly weak especially since the Scimitars are rather thin and easy to turn. When I turn the shaft by hand it has almost no compression also compared to another 90-4C I have here. Do you think it would make sense to rework the valves and/or change the ring?

Thanks in advance

1QwkSport2.5r

Your rpm is spot on where it should be. Don’t change a thing. Enya 90-4C (1)

sukhoi3

I have a Enya 120 non R. I purchased it and the exhaust threads are almost stripped not many threads still holding. Is the anyone doing a repair with a thread insert to fix this?