MikeEast

My Feedback: (3)

I did an RCU review for Horizon on the Evolution 45GX2 about 4 months ago and at the time I could get it to run but it was hard to start. Once it was running it purred like a kitten though.

I have been having a really hard time getting the engine to start and here is why. This is not mentioned in the instruction manual.

The carburetor is mounted to the engine backplate. from the factory the engine backplate is tapered so that the gasoline flows downhill from the carb into the engine when the engine is mounted right side up. If you mount the engine inverted (who doesnt?) the carburetor is sloping away from the engine so the fuel flows away from the reed valve and out of the carb on the ground unless the engine is running and vacuum is present in the intake. That is why it is SO dang hard to start.

Well today after I read a post on another forum I rotated the backplate (motor mount ) 180 degrees so that the taper allows the fuel to flow INTO the carb when the engine is inverted.

Heres the difference. I had almost given up on the engine because it was SO hard to start. Now that I have flipped the backplate the engine will literally fire on the first flip when choked and then starts on about the 3rd flip with the choke off..

NOW, I can say that the engine starts super easy and is turning up extremely well. Its pushing 7000rpms with a 22x8 prop and only about 3/4 of a gallon through it on break in oil.

This was akin to the heavens opening up today. It was a TOTALLY different engine after I made this correction.

huck328

My Feedback: (4)

How difficult was the rotation? Did you need a new gasket? I just spent the last 2 hours working out the mounting for my new 45GX2 on a Dave Patrick Extra and the carb is pointing downward, just like you said...

BaldEagel

Its not difficult but be aware that the backplate has two rubber O rings on it, therefore do not try to screw the back plate off, or use any tools, straight pull only, don't do what I did and then mount the carb back on upside down putting the carb pipe on the wrong connection. LOL. Make sure you take a note of how its connected up prior to doing this.

Mike

MikeEast

My Feedback: (3)

Rotating the backplate is very easy. Here is how.

1. Remove the carburetor from the backplate. Note the short clear hose is connected on top of the diaphram and the back of the back plate.
2. Remove the 4 screws from the backplate that are threaded through the backplate and into the back of the crankcase.
3. Pull the backplate off of the crankcase. DO NOT ROTATE THE BACKPLATE IN THE HOUSING. PULL IT STRAIGHT OUT.
As was mentioned in a previous post, the backplate is sealed by O Rings and its a snug fit. What I did was put a thin screwdrive blade under each of the 4 mounting legs on the back plate and lift each one a tiny bit at a time until I could pull the backplate straight out.
4. Once the backplate is out simply rotate the backplate 180 degrees and press it back into place. You can do it easily by hand. It rotates like a clock. With the carb off, you will see the taper in the backplate so just turn it so that the taper will lean the carb into the engine and the fuel will drain into the engine when the engine is inverted.
5. Reinstall the carburetor. The throttle and choke arms should be in the same place they were before. The carb should not be rotated in any way. The pressure fitting on the carb that connects the carb to the crankcase should be on the top with the engine inverted. You will need to cut a longer piece of fuel tubing to reach from the backplate vent fitting that is now closer to the head end of the engine. The tubing has to reach all the way up to the top of the carb at this point.
6. Reinstall the engine and you are ready to rock and roll.

Also, something that is not in the manual is the spark plug gap.. It should be .6mm.

MikeEast

My Feedback: (3)

One more thing. Mine is a little hard to prime when the fuel line from the tank is dry. I have found that it will prime very quickly if you choke the carb and go full throttle with the ignition off. Lift the tail as high as you can and still be able to rotate the prop. Flip the prop until you see the fuel go into the carburetor fitting. Then give it a couple more flips and it should be ready to go. If you dont pay attention to this and try to dry prime it with the tank sitting below the carb it may take 200 flips to prime. Just watch the fuel tubing and see do what you have to do. If yours primes without doing this consider yourself lucky. I have checked for airleaks and there are none. The pump in the carb just cannot seem to draft gasoline when the carb is dry.

oregonrc

My Feedback: (32)

The linkages will be on the same side, but the throttle and choke arms will be closer to the top of the cowl. At least that's the way it was on my H9 Extra 260. I had to relocate the throttle and choke linkages higher. Can't wait to see if it starts better.

oregonrc

My Feedback: (32)

Took the Extra out to fly today. Even after rotating the backplate, this SOB engine still won't start. I've messed with everything at this point. It must have taken 45 minutes to get that thing started. I tuned it and shut it down. I came back, not more than 5 minutes later and it won't start.
If I blow on the vent line, it's extremely restrictive. If I disconnect the inlent line going to the carb, the system moves freely. I've talked to Horizon Hobby 3 times now and it seems that they have noone there that knows these engines. One guy asked if my ignition battery was charged. What does that have to do with fuel flow? I had another "tech" guy tell me that it had been a while since he's flown an airplane that small. EXCUSE ME?!?! This was after I had a few install questions pertaing to this motor on a H9 27% Extra 260. Anyhow, the engine is being sent off to Horizon. I'm not ready to write this thing off yet, but I am wishing that I had bought the DA. I run a hobby shop in Oregon and I wanted to try another engine. I wanted to give the customer another option. After this...we'll see. If the engine comes back from Horizon in tip top shape, I'll be pleased. If anyone has any advice, I'd appreciate it.

bonedaddy41

My Feedback: (2)

All of this seems so wierd. I have a 45GX (not the GX2) that I have had zero problems with. From day one - 3 flips on choke and 2 flips to start. A flying friend had a 45GX that he said was a bear to get primed the first flight of the day. I just "assumed" that he didn't have his linkage adjusted right on the choke and it wasn't closing all the way. He gave up. Sold it and bought a used DA50. Now I am wondering if these engines are abnormal gassers and are sensative to tank location or something. There are way too many people having fuel delivery problems. I would be very interested in what you find out from Horizon since I have a GX2 and canister ready to go in a composite sukhoi.

Hans Meij

Step one: fill the tank
Step two: Pressurize the tank by another pinch or two in the bellows of the DuBro filler-cannister and blocking the tank vent. Leave it attached
Now flip, fuelline will fill quickly

oregonrc

My Feedback: (32)

We really shouldn't have to go through that. I've got flying buddies with 3W's, Da's, etc, and they all start and run great. This engine has been advertised to be lighter and more powerful than the DA50. Considering that it's in the same price range as the DA, I personally expect to have a low maintenence, strong running engine. Hopefully, Horizon will come up an acceptable solution.

BaldEagel

All you have to do is close the choke, open the throttle fully and flick until the fuel gets to the engine, about 6 flicks I find works, then switch on the ignition and it should start about second or third flick, you only have to do this if the fuel feed line is empty.

Mike

BaldEagel

oregonrc

Excuse me if I am telling you something you already know, but I assume you have the crankcase pressure line attached to the cast cover on the carb?

Mike

oregonrc

My Feedback: (32)

I appreciate your advice, but I've tried all of that. It will not prime with the choke closed and throttle at full or closed. The vent line and carb inlet line are attached correctly. That's why I don't understand this engine at all. That's also why it's on it's way to Horizon. I kid you not, I've got a sore shoulder from flipping that thing so many times. [:@] Anyhow, I really do appreciate everyone's input. I'll update everyone once I get it back.

MikeEast

My Feedback: (3)

OK,
I have more information and mine is running great now. Here are some other things to know.

It is hard to get primed but once you got it you got it. I really studied the carburator hard and figured out exactly how it works. Its just a standard Walbro carb so just set the needles where they tell you, 2 rounds on the low needle and 1 1/2 rounds on the high speed needle. That will get it running and you can go from there.

Now, to get it to prime you can do 2 things. 1 you can tilt the plane forward and choke it full throttle with the ignition off. Give it a few flips, if you can see the fuel tubing you will see it flow up to the carb.
Or, you can pull the fuel line off at the carb and lower it so that it fills by gravity. I prefer the first route. Once you have the fuel up to the carb, flip it about 5-6 times choked and full throttle. This will wet the carb and get fuel into the engine.

Now rotate the prop to bottom dead center and turn on the ignition and you should hear it clear the spark plug. This is crucial, if you dont hear anything,,, something is wrong with the electrical connection, see below. It may even pop and smoke as it burns off the fuel... Thats ok, just stay away from the prop. Leave it choked and 1/2 - full throttle and it should fire within 5 or so flips. Turn the choke off and it should start with the butterfly about 1/8-1/4 open. I find that it fires right up on a higher idle.

THe issue with priming is with the reed block. The reed block was made of plastic to save weight and it is not perfectly flat and there is a thin gap between the reeds and the seating surface. The reeds should be seated tight against the block. This seal is a BIG part of what it takes to build up enough pressure to draft fuel and why it is tough to prime. I talked to the guys at Horizon and they suggest taking a close look at the reed block and using very fine sandpaper to true the sealing surfaces up. I did not, I just took the reeds out and trimmed the burrs off where the screws go through the reed, reed plate and into the reed block. This closed the gap a good bit and helped a lot. I just decided that I will do the choke trick with the plane tilted forward. Its very easy to do and it works. Once you get it primed it should stay primed unless you run it out of gas.

Here is another possible problem that just totally kicked my butt until we figured it out. I found that the plug that connects the ignition to the switch (supplied with the engine) is not the best fit. Its a snap fit connector and APPEARS to be a snug fit, but if it spreads even the tiniest bit it breaks the circuit from the battery to the ignition and the engine will not start. IT has to be tight tight. Use a Zip tie to pull it snug. You need to make sure that you have tight fitting connections all the way from the battery to the ignition.

Here is a test that identified the problem for me. Take the switch out of the circuit. rig up a connector using the supplied connecting pigtailand connect the battery directly to the ignition and set it so that you can disconnect it if you cannot kill the engine by other means. Once you get the connection made, try to start the engine. Make sure that the connector is TIGHT. I zip tied mine together with a tiny zip tie threaded between the wires. The engine went from VERY tempermental to starting right up and running GREAT.

We saw all sorts of issues because of this darned plug. At first it would not run at all.. Then, it would pop about every 100 flips... just enough to tease. THEN IT RAN... For a few seconds. Then it would not fire... Then it fired right up... but it would die the instant you increased the throttle...IT was SO frustrating. We found that the vibration from the engine running is what was breaking the conection in the plug. IT was just enough to kill it, then it would reconnect just enough to get a pop. That plug has to be tight... Let me say it again, that plug has to be tight...

Summary,
1. I guarantee you that the needles are not so sensitive that they have to be perfect. Set them at the factory settings and that will get it running, then you can tune from there as it breaks in. IF you are fighting the needles something else is wrong. EIther the carb has a plug in it or you have a bad electrical connection.

2. Check and double check all solder joints and connectors for a super tight fit. I actually ended up changing to either direct solder connections or deans. I did leave the ignition connector on, but I have it zip tied very tightly.

3. You should clearly hear the ignition clear the spark plug everytime that you turn the ignition on. You should hear it at the plug as well as at the ignition. Its pretty loud and it may even ignite the fuel so be careful. If it is not clearing the plug, you have a problem.
a. Check the connections.
b. check the spark plug gap. (.6mm)
If you are hearing the ignition clear when it should not, you have a wiring problem. Check the wiring connections and be 100% sure that they are tight.

4. Learn to prime the engine. Its not as easy as other engines. But the engine runs like a bat out of hell so its worth it and once you get it all right. The thing is just super easy to start and I think it will outperform a DA50 by a good bit.


I think that there are 4 things that will get ya.
1. That darned little ignition plug, get it good and tight.
2. The reed seal, or lack there of.
3. A low battery output.
4. An air leaking, plugged up or incorrectly assembled carb.

MikeEast

My Feedback: (3)

I feel ya.. I have been on the phone with Jim and Pete from Horizon for a couple of weeks. As I wrote above, we finally figured it out.

I can TOTALLY relate to the flipping problem. I have literally flipped mine for 3 hours trying to get it to go. I was sore for 2 days after last Saturdays session. That bad plug I mentioned in my post above was killing me and I did not know it.. We thought it was a fuel mix problem becuase at first it would not run at all. I went all over the place with the needles. Then it would run for a few seconds and die.. We figured out that the vibration as the rpms were increased is what opened up the plug and broke the circuit causing it to die,,, but it looked EXACTLY like leaning out and dying.

If you cannot get it primed by tilting the nose way down (I put mine on the table so I could get more vertical) then just disconnect the fuel line at the carb and let it pour out. THen pinch it off and reconnect to the carb.. It will pull it the last little bit into the carb. IF it will not, then pull the carb and the reed block out and look at the reeds. I bet you have more than a business card thickness gap out at the tips of the reeds.

If it still wont start you need to check the electrical connections. If the ignition is working then I GUARANTEE you that you have a loose(enough to break the circuit) connection. Especially check that black snap connector that is supplied with the engine.. If it is even the slightest bit loose it will break the circuit... Zip tie it tight and I bet you it will fire up if the battery is hot.

MikeEast

My Feedback: (3)

That wont work.. I made a balloon out of my fuel tank trying to pressure the fuel into the tank. YOu have to let gravity help. If the get the reed block to seal off, the problem should go away.

oregonrc

My Feedback: (32)

It's not an ignition problem. I've got plenty of voltage and I can clearly hear the plug clear when the ignition is turned on. It is most definately a fuel delivery problem. With the choke closed, and the throttle opened, the motor is impossible to prime. It "wants" to prime better with the throttle closed. As far as removing the fuel line from the carb to start it...that requires removing the cowl. The hell if i just spent $600 for a motor that I'm going to have to remove the cowl to start it. I haven't looked at the reed block, though. I did remove and rotate the backplate. Maybe I should look at the reed block. That's one very good suggestion that I haven't heard. And, it makes a ton of sense. I'll give it a shot tomorrow. Thanks for all the help! I'll let you know.

MikeEast

My Feedback: (3)

I had plenty of voltage too and mine too would clear when the ognition was turned on.. I had the exact same scenario. It was the vibration from the start attempt that was breaking the circuit and preventing the spark plug from continuing to fire as the prop rotated. As soon as the prop was back at rest all was well and it "looked" like my ignition was perfectly fine. Like you, I could not see a problem when the engine was at rest, it was while it was rotating and shaking the plane whether it was actually running or not that it was breaking the connection due to vibration.

That is not to refute what you are seeing with your fuel delivery problem as I have the exact same problem as you are with getting the engine primed.

I would try 2 things just to see if the engine will run at all.
1. Take the cowl off and get fuel up to the carb, whatever you have to do. Mine will not prime (initially) without tilting the nose forward either. Get fuel into the carb whatever you have to do.
2. Check that plug and just make sure that it is not separating.. Turn the ignition on and wiggle the plug around. See if you can pull on it and break the circuit(without actually pulling the plug apart) and then re establish the connection so that you hear the plug clear then clear again without turning the ignition off.. Just check it, that may not be it but if it is it will sure save you the misery that I went through.

Once the engine is primed and that plug is tightly secured(zip tie works really well, (or just change to a Deans connector) try to start it again. It might take several flips to get the thing to pop for the first time... But once you do take off the choke and it should start at about 1/4 throttle with 3-10 flips.

If it STILL wont pull fuel, either your reeds have too much gap or you have a leak in fuel lines or the carb somewhere that is breaking vacuum.


Homor me and just try... I very sternly scolded Paul at Horizon after he persisited about electrical connections being the problem but in my case he was right on and I had to apologize to him. He was also right on about the reeds.

eugene

I'm trying to understand something here......cheap connectors, faulty plastic reed valves, with the cowl removed, it takes an engineering degree to get it to run??? And folks are paying $600 bucks for this?? Horizon must also be selling real estate..

oregonrc

My Feedback: (32)

Eugene, I somewhat agree with you. Every manufacturer has their problems, though. I've seen DA's, 3W's not run so hot either. We really shouldn't have to rework the wiring or sand the reed block to make our new engines run, though. Keeping in mind, Horizon does not manufacturer these engines. From my understanding, they are made by MVVS and distributed by Horizon. As ticked off as I am at this engine, I would never hold Horizon personally responsible. I'd like some of their tech support people to be more knowlegeable, though. I've certainly received more help on this forum than I ever have from Horizon. Once again, thanks Mike, I'll work on that motor today.

oregonrc

My Feedback: (32)

One more question. Should I be able to blow into the fuel inlet nipple on the carb? It seems very restrictive. Almost to the point where it feels like no air is getting through. If no air can get through, how can fuel?

MikeEast

My Feedback: (3)

Well,
its really not nearly as bad as it sounds. They are really very simple problems to resolve but they "look" like a carburetor problem and can really have you chasing rabbits with needle settings if you dont understand what is happening. Once you know what the possible problems are it takes about 10 minutes to work it out and the engine should run perfectly. AS far as the connectors I would not call them cheap and they are very simple to change to deans connectors. That is something I do on all of my 35% planes anyways.

The issue that is the most irritating is the reed block issue that makes the engine very difficult if not impossible to prime by conventional means. Once again, now that I understand what it takes to get it primed I can do it in no time at all. I can get the engine primed in about 30 seconds. Just tip the nose down as far as you can and still spin the prop and go to full throttle choke and give it 6-10 flips and its primed.

However, the reeds become a non issue once the engine is started. They seem to seal off just fine as the engine generates just a ton of compression and honestly performs as well as if not better than the DA50 just for comparison. Again, mine is turning a 22x8 at 6900-7000RPMS on break in fuel. I have 1 tank over a gallon though it so far. I expect it will turn a 22x8 in the 7500RPM range and a 23x8 near 7000rpms by the time its broken in right if it continues to perform like it is.



Not really, The fuel does not just freeflow through the carb.. Its pumped through a series of sections in the carb, and the fuel moves from section to section with each cycle of the engine as the conditions go from vacuum to pressure, over and over. Its sortof a batch operation where a drop of gasoline travels to a room and has to wait on the door to open, then to the next room and wait on another door to open, ( cycles VERY quickly) until it finally ends up in the jet chamber where it either flows through the high speed or low speed jet and out into the throat of the carb where it gets sucked into the engine. The low speed jet is a larger hole and gasoline will gravity flow through into the throat.. The high speed needle is a much smaller hole it it requires a vaccum in the carb throat to "suck" it into the engine. ( i know I know, vacuum is not about suction its about pressure differential all you eng's. I am just keeping it simple. )

Here is a great link to how it works

http://www.aerocorsair.com/id27.htm

vanguard

My Feedback: (25)

I am going to pass along this thread to one of the guys at our club. He has this engine, a 45 GX, and it is always a bear to start. I have watched him flip this thing till he is blue in the face. On more than once occasion he has had to resort to a fellow members electric starter. This info will surely help him with his engine.

oregonrc

My Feedback: (32)

Great replies, Mike. Again, I can't thank you enough for the help. I did sand the reed block, but haven't had a chance to start the engine. Hopefully, this will remedy the starting problem and I can avoid shipping the engine to Horizon.

Dave

MikeEast

My Feedback: (3)

Dave,
What did you find with your reed fit? Were they gapped at the tips and were you able to close the gap some and get the reeds to lay flush on the reed block? Are they sealing off now? You can test it by putting your mouth over the reed block and blow back towards the carb. It should seal off and stop the airflow when you blow on it. Even with the reeds not seating correctly it works great when the engine is running because the engine generates a lot of back pressure, enough to force the reeds to close off. The reed fit is more critical when the engine is being cranked and not running yet, as you you relying on the reeds to seal off with very little back pressure from the engine so you can generate enough pressure differential to move the diaphram in the carb and pump the fuel...

Also, just for grins, make sure that the diaphram and gasket are fitting correctly on the inlet side of the carb, heck the outlet side diaphram too (the one with the metal wagon wheel that is moved by the float needle on the side of the carb where the needle jets are located). If they are not in there right and you are leaking, that too will hinder the diaphram pump from being able to draft fuel.

Also, I don't want to give the impression that I am some sort of expert on Evolution engines. I am not. I am just an end user like you guys are. I have just fought this engine so hard and unnecessarily and the final solutions were so simple that I hate to see other people struggle with what I have already gotten help to figure out. SO I thought I would share my experience. Maybe I can save someone some time and frustration and possibly giving up on a really great engine. And maybe someone else has some other helpful info to make this engine easier to get going for all of us that are/were struggling.