Evolution 58gx2
 

What octane gas is best for the Evolution 58gx2? I have been using higher octane gas in my 45gx2 for 3 years and it is a great engine. The book is not clear on the octane for the 58cc, I have tried both and it still does not run as good as my 45cc. It has about 5 gallons of gas run thru it and I am using redline 40:1. Last week it ran great the first flight and after that it would not crank or it would not run over 5 seconds. The factory setting for the carb are 1&3/4 turns and I stay within 1/2 turn of that setting. I have two gas tanks that I rotate every six months to make sure the Tygon does not get stiff. I am using a 7.4v 2600mah Lion battery and a Mejzlik 24x10 prop and have never gotten over 6000 rpm. I finally sent it to Horizon last week. I am hoping they can find the problem.

RE: Evolution 58gx2
 

Good luck with your engine

It would be good for you to read the MVVS 58 Pro Sport Thread as they are pretty much the same engine and he has the same problem as you do.

http://www.rcuniverse.com/forum/m_9886726/tm.htm

RE: Evolution 58gx2
 

George,
The MVVS 58 turns the 24x10 well in excess of 6000. Alas, I could not tach the engine, because the plane decided to shed it's tail feathers in a burst of flutter.

MVVS engines and Horizon engines are made of the same parts, but there the similarity ends. Horizon does their own assembly.

RE: Evolution 58gx2
 

Thanks w8ye,
I have learned a lot from your post over the last 3 or 4 years. I have read everything on RCU about Evolution and MVVS gas engines and it seems like the 58cc has the most problems. Sometimes I wish I had waited for the MVVS LE 58cc, but my Evolution 45cc has been a great engine, the only problem I had was the muffler bolts, but that was an easy fix. I have always wondered if MVVS goes a little extra on their engines. I have a MVVS 26 and the Evolution 26 that seem to run the same in my Sundowner, although I have not run the MVVS as much as the Evolution. When the Evolution 58 is awsome when it is running right. This is the last video before it started acting up.

http://www.youtube.com/watch?v=5YbgD7Hx-vw

RE: Evolution 58gx2
 

Hello Pe,
That is very good info. It can make a big difference on how an engine is assembled. Would you say there are more problems with Evolution 58cc engines then MVVS 58cc's?
I am still thinking about the MVVS LE 58. If I can't get the Evolution fixed, I might have to get one of the LE''s. The 58cc is almost a perfect match for the AW 50cc Ultimate, I could not see going down to a 50cc after flying the Ultimate with the 58cc.
Thanks,
George

RE: Evolution 58gx2
 

Evolution 58gx2 mounted on AeroWorks 50cc Ultimate

RE: Evolution 58gx2
 

The only engine related problem I know (not counting the old Vlach ignition) is lubrication of the front seal. Easy to fix by a drop of oil between prop hub and crankcase every now and then.
26cc conrod problems were solved three years ago. Old engines will benefit from a couple of shims under the head.
LE is essentially a prosport, with bling colours
MVVS engines need premium fuel 91 PON or better with high quality oil. (.)  Lower grade fuel will very much shorten their life expectancy, unless you reduce compression ratio by adding shims. If you follow the manual, you'll be good.
Oh, before I forget. They need proper cooling as well. All mechanical repairs I had so far were heat related.

RE: Evolution 58gx2
 

Normal operating temp has been around 180F, the last time it ran, it was closer to 220F with an outside temp of 95F.

RE: Evolution 58gx2
 

There should be no cooling issues there.

RE: Evolution 58gx2
 

I received my Evolution 58 gx2 today. Horizon replaced the front and rear bearings, the front seal and the reed valve. I had rotated the back of the engine 180 degrees to angle the carb upwards for a better fit on the firewall. It came back with it in the normal position. I decided to mount it that way which required cutting a larger hole in the fire wall and swapping the throttle and choke servos. I tried to call the tech to see if he had a problem with the carb rotated 180 degrees, but never got in touch with him. Since it is still under warranty, I decided to leave it in the normal position. The weather looks bad for the weekend, so I will have to wait to try it out. The engine has less than 5 gallons of gas and I broke it in per the manual. With so much power you rarely run it full throttle. I will post the results of the test flight.

RE: Evolution 58gx2
 

Does it have any radial play now? I am trying to contact mvvs about increased radial play, but no answer as usual...

RE: Evolution 58gx2
 

No play at all, just like it is brand new. The repair notes stated it has an idle of 1600rpm and max of 6500rpm with a 24x10 prop.

Where do you send your MVVS for warranty repair?

RE: Evolution 58gx2
 

Some radial play is normal, as long as it is not the outer ring being loose in the housing. It is felt well in the prop because the bearings in the 58 engine are not very far apart. No radial play is what I would be worried about. As soon as a new or overhauled engine runs, it should become "loose".
I am not talking of excessive play.

About carb rotation:
I found no difference in carb rotation. If you have the engine inverted, starting is improved if the carb is angled away from the cylinder.

RE: Evolution 58gx2
 

Back to factory in Czech Republic I suppose. It's going to be winter soon here so no flying with bigger models anymore. I could change the bearins myself but what is the warranty for then? There should be better bearings in prosport model, but they are not listed in parts pdf file. I have the normal version.

RE: Evolution 58gx2
 

Agreed, determining what is normal and what is excessive is the hard part here. Pe, do you have any numbers and measuring suggestions?

RE: Evolution 58gx2
 

To measure, you would have to remove the prop drive, so you can set the dial directly next to the bearing.
I would think 0.01mm to be repair limit.
A loose outer ring in the engine housing is damage due to excessively hot running. (abuse).

PS.
That would be radial displacement from neutral. Total radial movement then is 0.02mm.
On the prop tip, that would be about 0.5mm for a single bearingif you apply slight pressure on the rear prop washer to and fro. However, the engine has two bearings, making it more difficult to measure without complete disassembly.

RE: Evolution 58gx2
 

After three 5 minute flights today, it seems there in no improvement in the low to medium throttle range. It has great top end, but it still sputters when it is not at the top end of the throttle range.
The carb settings are a little below two turns. When the low setting is around 1&3/4 or less, you don't have a good transition. The engine runs about 20F cooler with the richer settings.

RE: Evolution 58gx2
 

George, If you lean the Low end, you also need to open the High and vice versa. Low needle supplies fuel right up to WOT.
1 1/2 to 1 3/4 turn open would be ball park for a run in engine.
Other method:
set engine at very fast idle (2200 rpm). Turn the L-needle closed until rpm drop from fastest running. Open the needle 1/4 turn from there.
That would be basic setting.

RE: Evolution 58gx2
 

Hi!
Get rid of the small volume silencer!!!
Replace it with a cannister silencer and you will get more power and better throttling!

RE: Evolution 58gx2
 

This issue has cleared. It turned out to be a restrictive header in the model muffler system.

RE: Evolution 58gx2
 

Well..I recently purchased this engine, used, I'm afraid its not gx2, but the gx, although it came with user guide for the gx2.....the ignition box is black metal and indicates 4.8 volts...I thought I had made a good buy, but maybe not. I will not be using the engine for at least a couple of months...any ideas on what I should do? Thanks, B7

RE: Evolution 58gx2
 

can you post a picture of the ignition? how many magnets in the prop drive?

RE: Evolution 58gx2
 

Hope I can do this...these aren't great, I'll take some closer pics and post them later...Thanks, B7

RE: Evolution 58gx2
 

It seems you have the two-magnet Vlach ignition version. What is your problem? Have you run the engine yet?
If the ignition goes bad, conversion sets are available from RCexl and TSR. I have both in stock.

RE: Evolution 58gx2
 

I need a helping hand regarding an MVVS 58 Prosport (identical to the Evolution 58 GX2) engine
I have a brand new MVVS 58 Prosport, mounted on a 3D plan, equipped with an MVVS pitts muffler and rotating a VESS 24B propeller
The engine went through a break-in exactly as per the manual, and burned until now app, 2.5 gallons of fuel, were the first two were run using 98 Octane unleaded gasoline mixed with 3% of the supplied break-in oil, and the following 1/2 gal. was run using 98 Octane unleaded gasoline mixed with 2.5% of redline racing oil (the same one used in my DA 120)

Now for the problems.

1. The engine high end RPM is around 6100. It seems to be on the low side as my Chinese JC60 turns the same prop 100 rpm higher
2. The engine is not working "smoothly", mainly on the low to mid range
3. Engine vibrates much more than expected (prop is well balanced)
4. Most sever issue: The engine – when warmed up just a bit - after idling for more than 15 seconds straight – refuses to accelerate and cuts off immediately if throttle is advanced at more than a very moderate pace.
5. I have tried the following, with no noticeable change / improvement:
a. Removal of cowling to rule-out cowling-related over heating
b. All combinations of carb. needles setup
c. Replacement of spark plugs
d. Replacement of ignition battery
e. Setting of the ignition both to long – exhaust and short exhaust modes
f. Replacement of the entire fuel system (tank and tubes) with one taken from a perfectly functioning other model (the one with the said JC60)
g. Removal of the carburetor and checking of all diaphragms for flaws – non found
h. Check for dirt or clogging – non found
i. Bending the metering lever a bit upwards to allow more liberal fuel flow into the carb under acceleration

I am really out of ideas and would love to get some insight about that issue