I have a G62 in a WH Extra 300LX and put about 10 flights on the plane and then all of a sudden it kind of went to idle on one flight and it wouldn't take any throttle. If I gave it any throttle it would just pulsate. This happened on the last two flights. Ralph has checked out the ignition and it's ok so I guess I'm looking in other areas now. The fuel system seems fine and will hold pressure so I'm leaning towards and overheating issue. The problem started once the weather really started to get hot and humid outside. The pics show the cut outs I have on the plane. Does anyone see this as not being enough exhaust air for the engine to stay cool?

Not enough in for sure. Cut it higher in the front and add some baffles to make sure ALL the cooling air is cooling..
The outlet should be at lease 1.5x the inlet, of course bigger is better.
A picture of the spinner area would be most helpful too.

Do you have a pic looking more at the prop and level? Be interested to see where it actually enters and how it's going over the heads. Have to remmeber air is not going to go through the fins (which is optimal) unless directed... much like electricity it will find the path of least resitance.

Normally I find that engine start to loose power and then die if they are run hot..

Have you checked your battery under load? Pref. a 1 amp load just to see how it's holding?

I had an issue with my 62 last year. About the same thing I would take off (full throttle) as soon a s I back Out to start manuevers it would die. Myself and others couldnt figure it out, mixes throttle position, air leak<---(might look for that, the black spacer will crack if its to tight) I even rebuilt the carb 3 times before I chucked it out in the yard. So on to RCU for a new CARB and BINGO no more problems. $35.00 fix for me. well worth it. No more frustration. I would consider seriously looking at the ventury and all carb seats and the plastic throat it sits on. I found a crack in mine just last week. Good luck.

sinergy,

The only thing I have is a volt meter I got from tower and it has a load switch. The plane has been down for almost two weeks and the batteries have not been charged so I checked them earlier and they checked out at 5.6V. Here are some pics from the front.

Man do you think I can find one pic of my Cap from the front? See where the cowl has a sqaure part that comes ut right in the middle of the head? Iwould cut that up higher and show more of the head. On my 3w85 I actually used some depron and made a square that directs air right over the middle of the fins.


The voltage checker you are referring to only puts 250ma or 500ma load on your battery... if you have a field charger set it up for a 1amp discharge and wait 5 mins to see if the voltage drops quickly.

Looks to me like you have not enough of head getting fresh air and not enough room for it to escape.


Here are some pics as I was in the process... after it was done I used fiber finish from Maubid (where is he anyhow) to clean it up

OK good spinner pictures...
The openings around the spinner do almost NO cooling, but they add to the air flow that must go out the outlet.
So block off most of this area. A 3/4" circle on each side is enough, and more opening in front of the engine.

I think your a bit low on exit air. Put a lip on that hole in the back where the exhaust tubes exit. Maybe this will create a vacuum and pull more air through?

Carb:
http://www.davesmotors.com/store/product923.html

$69 [X(]

I used to find them on Sears parts site for $25, but their parts lookup is so frustrating--it's enough to make a guy want to run nails up under his toenails. [:@] Can't find them now.

Here's a pic of mine with one of Ralph's G62's in it. No over heating problems at all, but I do have a bit more opening in the bottom than you. I used to have a DA50 in it with a pitts muffler, so the bottom is all open where the muffler used to be.

It looks like your G62 is one of Ralphs. If so, you need to check the neoprene hose that Ralph used for the pulse line going to carb. Mine was only a year old or so and looking at it, it appeared ok. Take it off and stretch it and it was full of cracks. A buddy of mine was the same way. This could very well be your problem.....

Ok guys, I'm feeling better about this as we go along. I don't have a field charger so I can't check the ignition battery by putting a 5 min. drain on it but I did replace the battery. I think I will cut a square in the front of the cowl in the center of the head and then make a baffle of some sort to direct air flow. Would a baffle on one side be enough or do I need to do it on both sides? I'm trying to get this done before our meet on Saturday.

All of the flights before the problem started I did notice something. The engine ran a lot smoother at idle before I took off than when I landed. When I landed the engine seem to idle just a little higher and rougher. Would that have been a sign that the engine was getting hotter than normal?

Well... don't throw out that battery... its probably more heat related. Just have someone check it just to make sure... I was more trying to cover all the bases

I know you were sinergy and that was the first thing I did a couple weeks ago when this happened. I first thought the plane went into fail safe so I replaced the battery. I'm thinking more and more heat related now, it's just a matter of what I want or need to do about it. Thanks for the input dude.

I think it's mostly heat related as well. Cut an opening in the middle of the head similar to what Synergy has on his Cap. That makes a lot of difference. The exit area is ok but the top front of the engine is not getting much, if any cooling air. That's the hottest spot. If you were to run the engine with the cowl on and blow a bunch of smoke through the prop I believe you'd see almost all the smoke ramping down and over the head instead of into it. The shape of the cowl and the way it all flows to and over the muffler isn't a good combination. Follow TKG's advice and force the air down through the engine instead of going to the outside around it.

If you start up and engine and nearly immediately go fly, the idle when you land will always be higher than when you took off. The idle rises as the engine reaches normal operating temps. Taking off with a cold engine makes setting idles impossible. So what you are experiencing in that area is likely normal.

I know it'll sound like a broken record, coming from me, but I've seen it solve problems of this nature time and time and time again, so....

On Ralph's engines, there's a short (2-3" ) piece of black neoprene tubing from the crankcase to the carb, (you can see it in the left side of your first picture, I believe) providing pulse pressure for the carb. It likes to crack, break, dry rot, or otherwise suffer some sort of damage. Replace it with a length of Tygon or some other similar gasoline fuel line, and see if that doesn't solve the problem.

Many engines have that..... however the thing just came back from Ralph with a clean bill of health... I doubt that would get past Ralph.

Anything that easy is worth a second look. I doubt that's the issue as well but it's a simple check.

I'm like sinergy, it just came back from Ralph giving it a once over and I'm sure that when he didn't find anything wrong he started looking for something to be wrong. Just to be on the safe side I'll change the neoprene tubing. Ok, looks like I have a plan for after work today. I'm going to cut a square in the front to help cool the head more, cut another hole in the bottom of the cowl for more outlet air, change the neoprene tubing and go have a nice day of trouble free flying on Saturday. I want to say thanks to everyone that had any input in my problem. You can always learn more on the Universe.

Zippi

If you can, only do one thing at a time, so we can all find out what the real problem was. Overheating is my best bet, the air is going past the cylinder head isteaf of being directed through the fins, if you put a small lip in front of the rear air oulet it will cause a negative pressure downstream and draw air out of the cowl.

Mike

Hope those fix the problem for ya, Zippi!

For what it's worth...and this is just me...I'd try changing that tubing by itself, before I hacked the cowl up more. It's SUCH a simple thing to try, and IF it proves to be the issue, then you've saved yourself some time, effort, AND more holes in the cowl....why not, ya know?

I had some awfully mysterious problems with my RCIGN G-62 in a 25% PW Extra...with symptoms at least similar to yours. It was nogyro, actually (who recommended this same solution a few posts up *heh*) who told me about the issue on HIS G-62. Since then, I've seen or heard of no less than FOUR other RCIGN G-62's that had a rather wide range of issues....ALL diagnosed originally as either fuel or ignition problems...that have been "magically fixed" with this simple method.

As for Ralph "missing" such an issue...I, like many of you, think Ralph to be one of, if not THE, best in the business, particularly when it comes to Zenoahs. However, I know he's been advised of this issue but only quite recently....he may well have had your engine before then, and simply not thought to check it...or, he may have checked it and it looked fine (it often does...sometimes the TINIEST of cracks are hard to detect, but have made a difference), or, for that matter, he may have checked more 'common' systems (like the ignition) and simply not have thought about this thing. I certainly wouldn't "fault" him if any of those were the case, but at the same time, I certainly wouldn't "write off" such an easy solution.

In any event, as I say....hopefully ONE of the solutions presented here gets you back up in the air for, as you say, a day of trouble free flying.

Good luck!

If you had not had 10 good flights on this same airplane, I would be more inclined to question airflow and overheating. Something has changed in my mind. Before you cut up your cowl more, why not change out the ignition box with another if you have one, install a new heavy duty switch, and a new plug. Also check that throttle servo. If it is 3-pole, change it to 5 (I know, sounds crazy). If you still have the problem, then it is probably not electrical. I would then check the crap trap in your carb and check it for leaks or blockages. Again, overheating, IMO, would have been noticed from the get go, if that was the problem.

This is some good recommendations... however everything just came back from Ralph with his stamp of approveal. The post clearly states that the problems started when it got more hot and humid.

A switch is not going to cause an issue like this... its either on or off.. possibly intermittent.. however if you have that rare case it's not going to be a constant pattern only at high throttle settings... same with the servo really.

A little more on batteries...I told you of my experience on my 1/3 scale Matt Chapman Cap580. Turned out to be the onboard batteries were weak and, in the case of my plane, 8 digital servos sucking current from the battery all at the same time, caused a voltage drop sufficient to trigger BATTERY failsafe. Just like your plane, mine would go to idle and I would have to land. This plane had two JR battery packs, one a 3000mah and the backup, a 2400mah. After much investigation and head scratching, I finally found that neither one would charge up to the rated capacity and the 2400 wouldn't hold a charge at all. I replaced them with a SR 3500mah main/ SR 2200mah backup and have had no further issues with the plane going to idle in the air. SR batteries are expensive but so are airplanes.

Don't rely on the little voltage meter; I use it too but it will not tell you if a battery pack will hold it's charge or if it will charge up to rated capacity. The only way I know to find out is to cycle the battery and see how much energy it releases from a full charge to 4.4volts (this assumes a 4.8v system).

The battery doesn't seem to be your issue because the situation I described would have no effect on the way the engine idles. My situation was not an engine problem at all even though we thought it was the engine overheating (like you are thinking).

This is for what it's worth. If you really want to learn about batteries place a phone call to SR Batteries and talk to a guy there named Larry.

Yep...hotter more humid air raises your density altitude. Fewer air molecules in any given volume of air.

Meaning air pressure goes down...making the engine more reliant on what...well, gee...pulse pressure perhaps?

Just sayin...just because something fits the facts doesn't mean it's the only answer or solution.

Try http://www.vepetersen.com/

I bought a carb from them for $40 including shipping, same carb Horizon wanted $52 + shipping for.

I hear you and agree.. it's not always obvious. I just think because it was just at Ralph's (I am assuming he knew about the issue and checked it) it was checked.

Either way... tons of good info here.. Poor Zippy will be checking things all night

Although I might almost bet tomorrow's flying will be trouble free