RE: Quadra 52 won't run under 3500 HELP

RE: Quadra 52 won't run under 3500 HELP
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Gas Engines >> RE: Quadra 52 won't run under 3500 HELP

Page: << < prev 1 [2] 3 next > >>

Login

Message

<< Older Topic Newer Topic >>

RE: Quadra 52 won't run under 3500 HELP - 3/6/2008 6:08:56 PM

jimcork1

Posts: 934
Joined: 1/29/2002
From: Slidell, LA, USA
Status: offline

AirTech I bought it new in the box from the hobby shop when they were selling new. So it is a new engine. There was never any fuel stored in the engine after running. I have about 15 flights on the plane but only 1/2 to full throttle. The throttle arm is only a approx 90 degree arm and does not go 180.

I have checked the butterfly and it makes a tight seal and has a detent to prevent if from being installed incorrectly.

Today I put in all new "rubbers" and tried again. Once again.. 3000 rpm to 7200 rpm was solid. But I can't land at 3000 rpm unless flying the wheels force touchdown. Yesterday I attempted to fly with the restrictor plate and it did fly but on idle back it shut off and dead stick against a 15 mph wind with a 19# plane. Didn't make the field landed 6' short but enough to hit the briars and punch holes in the wing and crack the canopy.

So I am a bit frustrated with this carb/engine. I have examined the engine and found no damage the piston still looks like new and it is just beginning to break in a bit even if it is at the higher rpm. There is no mechanical binding. I am using 50 : 1 Belray full synthetic oil then switched to different conventional oil at 40:1 still no idle. Fuel from friend who flies gas burners would not get it to idle eventhough the fuel worked in his gas burner well.

The choke I installed makes it easier to start as it mounts on the intake only and does not restrict normal air flow. All the passages in the carb are clear and have been flow tested. The float lever arm was replaced / adjusted as per ZAMA instruction.

So far nothing has worked and I am arriving at the conclusion this is the wrong carb for this engine. I can't believe it was sold and won't get idle below 3000. I also have the C&H jump start for easier starting. If I leave the jump start on the engine has very solid ingnition and still no idle below 3000 rpm. Plugs changes to different brands/types/gap have had no effect on idle.

I have tried EVERY suggestion but no idle. There are no air leaks I can find on the crankcase as there is a good vac at the air intake on my thumb when turning over by hand.

So I am about to give up on this one unless there is some magic wand to wave.

Jim

(in reply to AirTech)

Post #: 26

RE: Quadra 52 won't run under 3500 HELP - 3/6/2008 7:36:44 PM

AirTech

Posts: 408
Joined: 1/28/2004
From: Allen, TX, USA
Status: offline

Jim,

Hang in there buddy and give me some time to consult with a couple of experts on these brand engine. For better assistance could you send me the S/N if there is one stamped on the case.

You say this was a brand new engine when you bough it. Taking in consideration that it's quite hard to start there is the possibility the pump diaphragm may be too hard from lack of use, but that is just my best guess.

After I talk to my friends I'll send you mail.

(in reply to jimcork1)

Post #: 27

RE: Quadra 52 won't run under 3500 HELP - 3/6/2008 8:03:14 PM

jimcork1

Posts: 934
Joined: 1/29/2002
From: Slidell, LA, USA
Status: offline

quote:

ORIGINAL: AirTech

Jim,

Hang in there buddy and give me some time to consult with a couple of experts on these brand engine. For better assistance could you send me the S/N if there is one stamped on the case.

You say this was a brand new engine when you bough it. Taking in consideration that it's quite hard to start there is the possibility the pump diaphragm may be too hard from lack of use, but that is just my best guess.

After I talk to my friends I'll send you mail.

I changed the pump diaphragm and it had no effect. I agree with you it really takes excessive starting to get it to run. Only with add on choke will it run.

I did have a brain dump today and found B&B still warranties and sells Quadra. I called them just to see if they had carb parts or what carb they were using. Spoke to Dick Bennett owner. He wanted to know if I bought it from him,, I told him local hobby shop and engine was new but didn't have papers. We discussed all the issues and he reco. send it to them as they had some issues with Walb carbs. I told him mine was Zama and he said he never had an issue with them but to send it to him for a look and test run. Since this really is a new engine just been in the box for a while I sent it to him to see what he can do. I have never touched the engine only the carb and he will see it is a "new" engine as the exhaust isn't even blackened yet.

So I am still interested with what the "brain trust" might come up with for options as this story continues. Considering I actually paid the LHS close to $500 for this engine I would hate to sell it on ebay for $75. I would expect it to run. But if I get it back and still have a problem I'll take more action to see if it will run properly. It is a very solid engine just can't imagine it won't idle down. Dick did say he recommended a 20x10 prop and I have been running 18,, but that should not kill the engine at 3100 rpm. I suppose you can read the frustration on this Quadra. Let me know what the brain trust recommends. Sorry I didn't get the SS # before I sent in this morning. Jim

(in reply to AirTech)

Post #: 28

RE: Quadra 52 won't run under 3500 HELP - 3/6/2008 8:05:26 PM

AirTech

Posts: 408
Joined: 1/28/2004
From: Allen, TX, USA
Status: offline

Hey Jim,

Seems like you are on track to solve your problem. Talked to Dick at B&B Specialties and he told me your engine is on its way there. If Dick can't fix it no one can. BTW he runs one the most honest operation in the hobby and is a real gentleman to do business with.

He seems to agree with me that probably the pump diaphragm membrane may have hardened after such a prolonged time in storage. I'm sure Dick can easily overhaul your carb but if I were in your place I will consider upgrading to a Walbro that fits. Dick will be more knowledgeable than anyone to set you up with the correct model Walbro.

Good luck and happy flying.

(in reply to jimcork1)

Post #: 29

RE: Quadra 52 won't run under 3500 HELP - 3/6/2008 9:39:50 PM

jimcork1

Posts: 934
Joined: 1/29/2002
From: Slidell, LA, USA
Status: offline

From my short conversation with B&B Dick seem to be a straight up guy. So all is in his hands. I just hope he can find the problem and correct it. I would really like to know. Remember I did replace all the diaphrams with new ones and this did not correct the problem. SO fingers crossed. Jim

My only regret is I can't be there to see what he finds and that I waited so long to return it. I bought it at the local hobby shop and looked today closer and it showed B&B as the warranty service. Didn't know where the hobby shop got the new engine from as he is no longer in business. Finding B&B as warranty is how I decided to call because I just have to believe the engine will run better that this. The local hobby shop closed after Katrina shut down most of the hobby stuff and wasn't around to ask.

I have converted many weed eater motors to r/c and never had this much issue with a conversion running. So I was a bit suprised to find a commercial r/c engine not running correctly.

(in reply to AirTech)

Post #: 30

RE: Quadra 52 won't run under 3500 HELP - 3/6/2008 10:37:09 PM

AirTech

Posts: 408
Joined: 1/28/2004
From: Allen, TX, USA
Status: offline

I missed the fact you had replaced all the diaphragms already. That make it very interesting to find out what the cause of your problem may be. Please keep me informed as to what Dick diagnoses the cause of the problem turns out to be.

I reiterate, Dick is a very professional gentleman and he will let you know exactly what's the cause of the problem is and how to better fix it. I am sure he will have the engine back to you in very short time.

(in reply to jimcork1)

Post #: 31

RE: Quadra 52 won't run under 3500 HELP - 3/7/2008 12:19:21 AM

Safebet

Posts: 654
Joined: 9/25/2004
From: Diana, TX, USA
Status: offline

Please, keep us posted as to the outcome. This has been very interesting. I appreciate your sharing this problem. I can tell by your posts that
you are somewhat knowledgeable. persistent and thorough. Now, I am anxiously awaiting your report. I know the problem is going to be solved.

_____________________________

Jim Vines
Diana, Texas
AMA 821369

(in reply to AirTech)

Post #: 32

RE: Quadra 52 won't run under 3500 HELP - 3/7/2008 1:22:12 AM

tkg

Posts: 2151
Joined: 1/6/2002
From: Riverton, WY, USA
Status: offline

If your absoluty sure the carb is closing all the way and has no leaks then you have a air leak in the engine.
No way an engine is going to idle at 3000 rpm with no air.going through the carb.

_____________________________

TKG
To much power is just about right.

(in reply to Safebet)

Post #: 33

RE: Quadra 52 won't run under 3500 HELP - 3/7/2008 1:30:15 AM

jimcork1

Posts: 934
Joined: 1/29/2002
From: Slidell, LA, USA
Status: offline

quote:

ORIGINAL: tkg

If your absoluty sure the carb is closing all the way and has no leaks then you have a air leak in the engine.
No way an engine is going to idle at 3000 rpm with no air.going through the carb.

I agree, what I found was that the low speed needle had little effect on the rpm as I could not get below 3100 rpm. Since this was a new out of the box engine if there are any leaks that aren't from the carb perhaps B&B can find them. It would not run any with the intake fully closed so I really don't suspect a leak on the engine itself.

(in reply to tkg)

Post #: 34

RE: Quadra 52 won't run under 3500 HELP - 3/9/2008 12:58:50 AM

Flypaper 2

Posts: 4306
Joined: 3/29/2002
From: Kingston, ON, CANADA
Status: offline

Don't remember seeing a Zama carb on any Quadra unless someone changed it. Where is the throttle butterfly when it's running at 3200 rpm or when it shuts off. Cyl. gasket could have a piece out of it but should spray fuel out if it is.

_____________________________

Gord
Dreamed I was a muffler. Woke up exhausted.

(in reply to jimcork1)

Post #: 35

RE: Quadra 52 won't run under 3500 HELP - 3/9/2008 1:59:12 PM

jimcork1

Posts: 934
Joined: 1/29/2002
From: Slidell, LA, USA
Status: offline

quote:

ORIGINAL: Flypaper 2

Don't remember seeing a Zama carb on any Quadra unless someone changed it. Where is the throttle butterfly when it's running at 3200 rpm or when it shuts off. Cyl. gasket could have a piece out of it but should spray fuel out if it is.

This one came new with the Zama. Dick at B&B told me they could have either the Zama or the Walb.

I think the carb it too big for the engine and at low throttle there isn't enough airflow over the ventura to keep the engine running. I measured the carb opening and it was 11/16" with the actual barrel at ~5/8". I have never seen one that large. I experimented with restrictor plates and with a 3/8" plate on the intake the engine idle went to 2700 rpm,, from 3100 rpm with no restrictor plate. The restrictor plate allowed the engine to pull more vacuum on the ventura to test my theory of too large a carb intake. For every 100 rpm lower in idle the top end also came down 100 rpm. With no restrictor plate and a 18x10 prop top end was 7200 and bottom 3100. With the restrictor plate the top end was 6800 rpm and bottom 2700 rpm. The recommended prop is 20x10 so I would expect higher rpm with smaller prop. Given the 18 " prop is a tad bit lighter you might think that would affect idle but it did not have any significant effect. When the engine would shut off at idle the low speed needle valve was totally ineffective in changine rpm. Which lead me to the thought of too low a vacuum in the intake at low rpm. So we will see what B&B finds to make it run as design. This is why I sent it to them to check out.

(in reply to Flypaper 2)

Post #: 36

RE: Quadra 52 won't run under 3500 HELP - 3/9/2008 2:46:52 PM

soarrich

Posts: 2372
Joined: 2/1/2002
From: Middletown, NJ, USA
Status: offline

quote:

ORIGINAL: jimcork1

quote:

ORIGINAL: Flypaper 2

I experimented with restrictor plates and with a 3/8" plate on the intake the engine idle went to 2700 rpm,, from 3100 rpm with no restrictor plate. The restrictor plate allowed the engine to pull more vacuum on the ventura to test my theory of too large a carb intake.

This is interesting, I would not have thought a restector plate would have any effect on the idle. The only effect I could see it having is turbulating the air/fuel mixture so it was mixed a little better, but at idle the engine shouldn't "see" it.

_____________________________

Rich Border

(in reply to jimcork1)

Post #: 37

RE: Quadra 52 won't run under 3500 HELP - 3/9/2008 3:10:27 PM

Flypaper 2

Posts: 4306
Joined: 3/29/2002
From: Kingston, ON, CANADA
Status: offline

Stock carb is a Walbro WA 144. Venturi bore size is 1/2 in. As you say, stock prop is 20 -10. Should swing it in the low 7s. Mag. ign. should idle at around 2100 rpm. Rebuilt one last summer for a club member converting it from 50 to 52 and rebuilt bent crank. Second flight he rolled it at about 200 ft. and the batt. fell out. Full throttle straight down. Buried the motor about a ft. Firewall was molded to the back of the motor. Bummer. I'm sure yours will run fine with a good carb. To late now but you should be able to take the low needle out and blow air in and it should come out the three holes you see where the butterfly closes. These are only pinholes. If the last hole is plugged, it will shut off before the butterfly closes. At full throttle, it is still going through those three holes.

_____________________________

Gord
Dreamed I was a muffler. Woke up exhausted.

(in reply to jimcork1)

Post #: 38

RE: Quadra 52 won't run under 3500 HELP - 3/9/2008 5:08:09 PM

jimcork1

Posts: 934
Joined: 1/29/2002
From: Slidell, LA, USA
Status: offline

quote:

ORIGINAL: Flypaper 2
To late now but you should be able to take the low needle out and blow air in and it should come out the three holes you see where the butterfly closes. These are only pinholes. If the last hole is plugged, it will shut off before the butterfly closes. At full throttle, it is still going through those three holes.

Not too late that is one of the first thing I did and it confirmed all 3 passages were open.

I actually found a ZAMA manual on line that gave all the test for the carb and did all of these test as the first step.
The carb basically checked ok but the engine still would not idle,, that's why I went to restrictor plate. If you notice the correct Warb carb has a smaller throat than what I measured on the zama.

(in reply to Flypaper 2)

Post #: 39

RE: Quadra 52 won't run under 3500 HELP - 3/9/2008 5:28:40 PM

Baldeagle

Posts: 1448
Joined: 2/2/2002
From: Lakeside, AZ, USA
Status: offline