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quadra 50 dead stick on vertical upline

Old 11-25-2006, 05:59 PM
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MatriX40
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Default quadra 50 dead stick on vertical upline

hello, im new to gassers. i picked up a quadra 50 and i have it on a 27% cap 232. i have not flown the plane yet. but im performing the pre-maiden flight checks. i have a 20x8-14 prop on it and the engine has already been broken in by the previous owner, and i know this isnt the best prop. but i got it with the engine, anyways the engine will not run with the choke completely opened and when the plane is lifted into a virtical position the engine dies immediatly. with it choked 1/2 way it sounds strong but i am only taching out around 5600 rpm. i thought this was low. maybe i need to tune the carb better, im not sure. And it appears that there are no airbubble in the fuel line when engine quits. any thought, opinions or suggestions are greatly appreciated thank you
Old 11-25-2006, 08:06 PM
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w8ye
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Default RE: quadra 50 dead stick on vertical upline

How's your idle? There's another post near this one where a person had the rear seal leaking. There's a front seal also.

I've seen 41/42's do this with a bad rear seal caused by the spring starter. There could also be a crankcase air leak somewhere else?

The give away is that your choke has to be partially on. Another give away would be the engine is hard to get to pick up the fuel and finally run.

Before you get too excited, try making the mixture a little richer and see what you have?
Old 11-26-2006, 12:10 AM
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Default RE: quadra 50 dead stick on vertical upline

I suspect one of the following conditions may be causing the problem;

In light of the fact that you bought the engine used, you don't know the history, age or maintennce of the engine. Based on my experience, I would try:

1. Check your tank's clunk to be sure it's toward the rear of the tank. You can do this most easily with a syringe (Sig 5oz syringe). Just draw fuel out of a half-full tank, then tip up the model and draw the fuel again and watch for air bubbles in the fuel line. Do this at the fuel line where it connects to the carb. Bubbles indicate that the clunk is not in the fuel or there is an air leak in the line. Remove the tank and check all the plumbing in tank and line up to the carb. The Du-bro filler valve is a notorious air-leaker; a better choice is a "Fuel Dot".

2. The carb pump and regulator become brittle over a couple years of storage. When that happens the pump diaphram in the Walbro carb becomes stiff and will not respond adequately to the crankcase pressure pulses and will not overcome the gravity head effect caused by lifting the nose of the plane. The pump just can't pump the fuel that high. The solution is to install a carb diaphram kit.

3. The carb screen may be plugged with debris. To check it, remove the pump cover (the single-large-screw side of the carb) and clean the screen if req'd.
Hope this helps.

Bill Jensen, BJ's Model Engine Service. www.bj-model-engines.com
Old 11-26-2006, 07:42 AM
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w8ye
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Default RE: quadra 50 dead stick on vertical upline

Bill,

Thanks for jumping in with your help.

Tried your link and it didn't work this morning.

Jim
Old 11-26-2006, 10:02 PM
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Default RE: quadra 50 dead stick on vertical upline

hi guys thanks so much for your suggestions! in reply to w8ye's comment on the engine idle. it accually idles very well. it does seem to take 7-10 flips with the choke closed and the ignition off to pull fuel from the tank but when the fuel is pulled into the carb, it starts right away. but like i said before i cant get full power out of it i think before i tear the engine down to examine or replace the 2 crank seals i will prolly try rebuilding the carb. or depending on the price i might even replace the carb with a new one. a comment was presented to me from a friend about installing a perry pump between the tank and the carb. i was curious to hear your opinions on that comment thanks again for all your suggestions im sure they will help me get to the bottom of this problem
Old 11-27-2006, 06:47 AM
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w8ye
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Default RE: quadra 50 dead stick on vertical upline

The Perry pump deal seems to be a waste of time with the type carburetor you have on your engine. Your carburetor has a pump on one side and a demand regulator on the other.

A repair kit for your carburetor should be rather cheap? I bought a couple repair kits last year this time. The same kit repairs all the WA & WT style carburetors. The problem with the ones at the field has been lint from a fuel filter collecting in a little screen near the pump outlet inside the carburetor. I bought the repair kit at the local chain saw dealer. They have a number something like WAT-10?

Enjoy,

Jim
Old 11-27-2006, 08:27 PM
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Default RE: quadra 50 dead stick on vertical upline

hi guys. just to fill you in i found the problem. i took my carb to a local lawn and garden store and the guy there sold me a repair kit. and he even tore my carb down and installed the repair kit cause it was close to closing time and he had nothing to do(LOL lucked out on that one). he also pointed out that the diaphram was plyable, but the edges were getting brittle, he acually broke a small piece off to show me how brittle it was. he said he wasnt sure if that was why it was shutting off. but it would be a good idea to replace it. so i installed it back on the engine and started her up. it ran fine once the engine was warm. the choke could be opened completely. i then held the plane upright into a virtical position and the engine still ran strong ( i was very excited LOL) so as i let the engine run out of gas i noticed a large increase of RPM's and when i was putting my plane in the garage i noticed the bottom was covered in oil. which gas engines usually dont leave a large amount of residue from the exaust. this is telling me i have the engine running rich that brings me to another question is there a ball park set up for the quadra 50's as far as how many turns out, the high and low end should be. i know it needs tached for any fine tune adjustments, im just worried about running it too lean and destroying the engine. but hey thanks alot guys i was pulling my hair out over this. and with your help my plane should be flight worthy very soon thanks again
Old 11-28-2006, 01:28 AM
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w8ye
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Default RE: quadra 50 dead stick on vertical upline

Your needles were probably opened up to try to get the engine to run with the bad carbuertor?

If I remember correctly the beginning setting for both the high speed and the low speed needles are 2 turns. What you wind up with after that would be anybody's guess?

I like to set the high speed first. I find the peak and or the maximum lean position and then open the needle back out a little.

I then lean the low speed needle down to the point where the engine starts to quit when given the accelerating gas from idle. Then I enrichen the low speed needle enough to get a good transition to high speed from idle.

The safest way to have the high speed needle set (And you can only do this by flying the plane) is to have the high speed mixture rich enough to where the engine is just beginning to four cycle after level flight for a ways. Then when you head vertical, the engine will go into a smooth two cycle.

To ease your mind, these engines seem to hold up well with too lean mixture settings. They will just sag on you in the verticals if too lean. I flew with a guy a few years ago that just had to have his engine running a smooth 2 stroke at all times. He never had one quit or burn up?

It is normal for them to make a "rung rung rung" sound when you first pull the power back as if to land.

The more important thing is to run a good 2 cycle ashless oil in the range of 32-40 : 1 ratio. There may be some discussion or other opinions on this?

If you find the high speed needle not responsive to adjustment, you probably have the low speed needle turned in too far?

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