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RE: BCMAEngines - 5/7/2006 3:57:52 PM   
sbaugz


 

Posts: 772
Joined: 6/17/2003
From: waukesha, WI, USA
Status: offline 		I agree, i think something is goofy. I checked things out again and there does not appear to be a leak in the fuel lines. I did notice, however, that since I ran it last night, there has been a bunch of fuel leaking all over the garage when I checked it this morning. It appears like the fuel is leaking out of the carb somewhere, so I am guessing that a seal is bad somewhere or another.

I might try swapping out to a spare carb that BCMA sent me with a choke on it. I was avoiding trying this "spare" carb out because the throttle linkage is somewhat goofy and wasn't as nice as the one I have on now, but I will try that one.

Now, you mentioned a two fuel line carb earlier. This spare carb has exactly that setup, which I am not familiar with. The second line is blocked off right now with a short segment of fuel tubing and a bolt threaded into it. Should i leave it this way?

(in reply to Scott Ellingson)
       Post #: 76

RE: BCMAEngines - 5/7/2006 4:04:15 PM   
Scott Ellingson



Posts: 1032
Joined: 8/10/2004
From: Avon, MN, USA
Status: offline 		Yes, leave it blocked. It is only used with a primer bulb and will work fine if it is plugged. If you don't like the fuel hose hooked to it, you can also solider it shut. See if it solves your problem first, but then you can use a solidering gun to put a bead of solider over the hole. Even crimp the end down first, then solider it. That way no solider will get into the carb.

You mentioned gas leaking from the carb. That sounds like the metering valve. It works like a float in a rgular carb like a car has. It is supposed to stop fuel from entering the carb when it isn't running and control the amount of fuel when it is running. I bet the new carb will take care of your problems. The small Walbro carbs have always been a little hit and miss for me. When they work, they work great, but somtimes they have trouble right from the factory. Walbro factory.

_____________________________

There is no replacement for displacement....you can allways throttle back!

(in reply to sbaugz)
       Post #: 77

RE: BCMAEngines - 5/7/2006 4:18:51 PM   
sbaugz


 

Posts: 772
Joined: 6/17/2003
From: waukesha, WI, USA
Status: offline 		allright, thanks for the help. I will swap out the carb and try that. Is it safe to say that most walbro carbs, regardless of model, will require approximately the same starting needle point? This other carb I am going to use is clearly a different model than the one it is replacing and I wonder if I should start around 2 turns out on this carb as my starting point. Thanks.

(in reply to Scott Ellingson)
       Post #: 78

RE: BCMAEngines - 5/7/2006 4:41:18 PM   
Herby 1


 

Posts: 10
Joined: 4/26/2003
From: Northern Arizona
Status: offline 		Some of the latest Walbro carbs are "environmentally friendly"...If you look at the threads on the needles you will see that they are very fine pitch...In order for the new needles to pass as much fuel as older ones they need to be open way farther than the needles on older carbs...
I guess "big brother" doesn't want us poor uneducated users to play with the needle settings..
Many of the carbs have plastic restrictors pushed over the needles to limit adjustments...
Throw the restrictors away and open the needles to whatever it takes...

(in reply to sbaugz)
       Post #: 79

RE: BCMAEngines - 5/7/2006 4:45:20 PM   
Scott Ellingson



Posts: 1032
Joined: 8/10/2004
From: Avon, MN, USA
Status: offline 		2 turns is usually a good starting point. It may need up to 3 or less than 2 to run good, but it will get you close. Most of the small Walbro carbs seem to tune pretty close.

On another note. I have a bunch of 26cc's here that are actually wht the SPE 26 is derived from They are exact except for the crankcase. They are for a goped, were the crankcase on the SPE is just for airplane use. Anyway, I have been test running one and now have 30 hours on it. It is running stronger every tank. SO rest assured your 26 will be a good engine. You just need to get the carb thing worked out, break it in and then it will give you years of flying. 30 hours is equal to 120 15min flights. I ran it for the 30 hours at 4500+ rpm. I figured that RPM was about an avarage rpm for normal flight.

_____________________________

There is no replacement for displacement....you can allways throttle back!

(in reply to sbaugz)
       Post #: 80

RE: BCMAEngines - 5/7/2006 4:48:02 PM   
Scott Ellingson



Posts: 1032
Joined: 8/10/2004
From: Avon, MN, USA
Status: offline 		RCIGN is correct. I have run into some carbs with the fine thread needles. I am just going by the carbs I have used on my engines for the 2 turn thing. If it is a fine thread needle it will need more turns for sure.

_____________________________

There is no replacement for displacement....you can allways throttle back!

(in reply to Herby 1)
       Post #: 81

RE: BCMAEngines - 5/7/2006 5:09:27 PM   
sbaugz


 

Posts: 772
Joined: 6/17/2003
From: waukesha, WI, USA
Status: offline 		Well, I tried the other spare carb and ran into some snags with that one two. So, here are my two scenarios:

1) first carb ran pretty well, but the needles are backed out 5 turns. As you mention, I may have a carb with fine needles. Nonetheless, the carb is leaking all over my garage, so probably one of the seals is bad or something.

2) second spare carb- an attempt was made to install today and the throttle linkage is not lining up right. The geometry of the throttle arm on the carb is wrong, so that when I go to full throttle, the linkage is exactly parallel with the plane, resulting in the linkage getting stuck. The only way this carb could work is if I had the throttle servo mounted to the side of the engine, which won't work. The other end of the carb linkage hits the engine case, so I would need to grind a bunch of that off to make it fit (its the part of the linkage that the spring attaches to so that the throttle will go back to idle if the servo fails. Anyways, I would have to grind half that off so it would not hit the engine case.

At any rate, I think I am going to drop BCMA a line, letting him know that I am returning both carbs and would like a new one, and more importantly, the proper one for this engine.

Thanks for the help everyone.

(in reply to Scott Ellingson)
       Post #: 82

RE: BCMAEngines - 5/7/2006 5:41:16 PM   
roknhs


 

Posts: 262
Joined: 1/15/2006
From: Tick Fever, ID, USA
Status: offline 		I've got a 26 coming one of these days........hope I don't run into your kind of problems.
Do you have other gas engines or is this your first? I've got a fair amount of experience with walbro carbs........G-26, Quadra 50, G-45 and I've done a lot of chain saw work as I logged my way through college. Never seen what you're experiencing. Its got to be that you were just unlucky enough to get a bad carb. Kudos to Poco and RCIGN for trying to help you through this little glitch as they are or maybe competitors of BCMA. That tells you something about those guys.......you gotta love people like that.
RS

(in reply to sbaugz)
       Post #: 83

RE: BCMAEngines - 5/7/2006 5:59:41 PM   
sbaugz


 

Posts: 772
Joined: 6/17/2003
From: waukesha, WI, USA
Status: offline 		I agree, that was very nice of them to help out.

This is actually my 5th gas engine, so I am pretty experienced with them. Currently, besides this spe26, I have a G26 and a DA50. I have also owned two different ZDZ40's as well. Never had any of these problems before, hence all the questions. Thanks again.

(in reply to roknhs)
       Post #: 84

RE: BCMAEngines - 5/7/2006 9:44:16 PM   
Herby 1


 

Posts: 10
Joined: 4/26/2003
From: Northern Arizona
Status: offline 		Gasser carbs don't leak unless the inlet needle is not closing off the hole, it takes at least 6 lbs pressure to unseat the needle...That could be part of your problem....A little piece of dirt can keep the needle from seating...

(in reply to sbaugz)
       Post #: 85

RE: BCMAEngines - 5/8/2006 5:59:22 AM   
Scott Ellingson



Posts: 1032
Joined: 8/10/2004
From: Avon, MN, USA
Status: offline 		Also an incorrect setting on the needle can cause it. If the rocker is bent up too fat it can also leak. Here is a quick pic of what we are talking about. This is under the bottom plate with the 4 screws. I have 2 pics. One pointing to the rocker that moves the needle, and the other of the guage to set it. RCIGN is correct. a piece of grit can cause it to stick open or a rocker that is way off. The grit could come from anywere. It could even be a shaving from when the carb was made. I have seen that before. At any rate, if you remove the screw that holds the rocker down you can remove the needle and blow the hole out to clear it. Thier is a small spring to watch out for. Then put it back together and make sure the rocker is just slightly above the aluminum directly around it. If it is too low it can run lean, too high and it can run rich. I can get you an exact measurment if you need it. It would be quicker to try it than wait for a new carb.

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< Message edited by poco242 -- 5/8/2006 6:00:55 AM >

_____________________________

There is no replacement for displacement....you can allways throttle back!

(in reply to sbaugz)
       Post #: 86

RE: BCMAEngines - 5/8/2006 12:22:54 PM   
sbaugz


 

Posts: 772
Joined: 6/17/2003
From: waukesha, WI, USA
Status: offline 		Thanks for the advice. I have since been in e-mail contact with Adam from BCMA and he has offered to simply replace the carb, which is probably just as well for me. I am in no hurry to use this engine, so I can afford to wait for a new carb.

(in reply to Scott Ellingson)
       Post #: 87

RE: BCMAEngines - 5/8/2006 11:47:34 PM   
blackbaron



Posts: 339
Joined: 9/25/2004
From: Longmont, CO, USA
Status: offline 		The 5 turns out on the carb is not where this carb should be set. With the needles set like that gasoline would be spraying out of the carb when you hit it with the starter. Something inside the carb is restricting or blocking fuel flow. Steve, I am not going to let you beat your head against this one so I will test another carb, set the needles and send it out to you. I still waiting on my shipment of engines and spare parts and will take care of that as soon as I can.

Scott and I colaborate every now and then trying to figure out wierd problems that happen with Walbro carbs. We both deal with brand new carbs and run into defective ones once in a while.

Poco242 and RCIGN1, thanks for helping Steve out. I have been absent on the board the past few weeks and apprechiate your help. You guys are an asset to this hobby!



_____________________________

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(in reply to sbaugz)