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PostPosted: Fri May 04, 2007 11:33 pm
by Chappy

You don't need crummy primer bulbs or heavy fuel pumps to prime diaphragm type carbs. I got fed up with the primmer bulbs many years ago, so I tried something different. I believe Ozzie has tried this after I told him about it and it's working for him too.

I ran a separate fuel line directly from each engine to the fuel tank. I drilled slightly smaller holes than required, and forced the lines through into the tank. A weighted Lazair fuel filter (the metal strainer style with the check valve ball) is then attached to each so that it can flop around a little on the bottom of the tank. Keep the fuel line routed so that there are no dips in them where fuel vapors can collect, just always going higher till they reach the carb. A third hose it installed as a vent. I used an automotive tire (tyre for you guys up North) valve stem, the kind they use on alloy wheels that attached with a nut inside the tank. This vent line is routed up and forward, and allowed to hang down at the end so the pilot can turn in the seat, reach it, and blow into it. In this vent line, up under the boom tube, a one way check valve is installed. I found mine at an RV parts store. It was sold for use in a water system, and cost less than $10 buck, IIRC. The fuel tank cap is not vented.

So, to prime the engines, all you do is reach under the boom tube, grab the vent tube and blow into it. You will see the plastic gas tank expand slightly, and it will stay that way after you have finished blowing into it. Now, when you pull the starter ropes and spin the engines, fuel will be "pushed" up the lines to the carbs exactly as if you had a primmer bulb, but you don't have the crappy things anymore to fail and get stiff. The check valve I used has a rubber flapper in it, but since it's so far away from the fuel, it's never failed.

Usually, it's not necessary to re-prime the carbs by blowing in the vent after the first time each day. If you do, just grab it and blow into it. I can easily reach it while seated in my Lazair. The check valve has never restricted the carbs ability to get fuel out of the tank on long flights.

I like it because it's simple, inexpensive, reliable and light. People can look at you kind of funny as they are trying to figure out what in the world you are doing blowing into the little tube...


PostPosted: Sat May 05, 2007 8:42 am
by daffy1029
Hi Chappy,
Jpxman does something similiar with his float bowl carbs (after a long time away from flying). He just adds a plastic bicycle air pump to the vent line, and pumps until there is fuel in the float bowls. After that, it always starts within two pulls.
I tried what you did with Jpxman's air pump and cranked the engine over and the fuel did not go up the lines. So I tried with electric fuel pump, same thing. Then from Lazaikid, he mentioned pressing the diaphram in, on the carb, and right away, the fuel is in the engine. So I am going to mount a horn button up high, where I can reach it, and the carbs at the same time. This way I can prime the engines, hop into the cockpit and start them. I have electric start now, and so getting power is not a problem. I only hope, that if I want to fly without engines, that they will restart, without pressing the diaphram again. Because, there is no way I can reach those carbs from the cockpit. I suppose I could add a "choke" cable to press the diaphram in...
Nice to hear from you Chappy, how is the "new" Lazair coming along?

PostPosted: Sat May 05, 2007 10:20 am
by JPXman
yes chappy, how is the other EC'er doing? we are a small group of 3 right now, though shorty says there is one for sale in southern ontario.

PostPosted: Sat May 05, 2007 11:35 pm
by Chappy
Hi Tyler and Daffy,

Well, the bad news is that I haven't touched it since I drug it home to Virginia from Oregon 18 months ago, although I have been collecting parts and materials as I come across them. I'm really looking forward to converting the 185s to CDI first.

The good news is that the house project I started at the same time I finally found the EC is just now finished. It's been a pretty amazing project, sort of on a par with building your first Lazair - just a lot more work and MONEY. And now, with the collapse of the housing market out here 40 miles from Wash, DC, I get to stay here and sell the new house that's just across the river from DC where the market is still decent. The developer that had contracts on the properties on three sides of me has gone into hiding, so I guess I'll get a reprieve and can stay out here with my space and shop for a few more years. By then I hope to be able to move onto a residential airport somewhere away from an urban area like I'm in now. Flying is just ruined here since 9/11.

In the background I have been sneaking time on several car projects. Two BMW's that I have just about ready to go back on the road (unfortunately, the convertible will be the second one, as the weather is getting very nice now), and am just beginning the teardown of the hot rod 340 engine that I'm going to rebuild for my '66 Dodge Coronet project. The Coronet will be a long term project, but I'd like to get the 340 into it as soon as possible just to get it back on the road until I have a shop where I will have the SPACE to do a teardown of the car for a modified restoration. I've just about run the engine out on my antique Chevy van during the house construction, and will probably throw a crate engine in it soon so I'll have something to pull my Lazair trailer with. Some of these projects have to get out of the way for the EC rebuild to begin, mostly because I don't have the space. Oh, and the '46 Champ needs the landing gear rebuilt, but I'm hoping I may be able to wiggle get out of that job.

Maybe I could hire Shortly to rebuild the EC? (Just Kidding). That's one mean sheet metal brake he built recently. I've wanted to make one like it for years, so I am very jealous!


PostPosted: Sun May 06, 2007 7:11 am
by uscgairdale
Maybe Shorty can't get an e-mail sent through Comcast because the inside of Lazairkid's computer is all rusted know, like the inside of a KFM!


PostPosted: Sun May 06, 2007 10:45 pm
by lazairkid
You can keep talking junk all you wont don't make no difference to me!

When I sold you the KFM's I told you I haven't done anything with them
since I purchased the Lazair and that they were last on my list to do.
I also told you that the cylinders had good compression and that the props turn
freely and they did.
I also showed you in detail the spots on the leading edge of the props for
witch you said no problem...
It seems obvious you couldn't tell there was anything wrong with them
during the time you had them, until you ran them.
And until you opened the engines up I had no idea there was rust.
NOW- You had my E-Mail and my phone number but I never got a call that
something was wrong with them.
Had you done so I would had given you your money back or paid for the
rebuild of the engines but instead you chose to post photo's and TRASH ME on this web page.
I have done nothing but try to help others get there lazairs in the air.
If I remember wright I sent you trailing edge material that I had left
over to do your wings free of charge and I paid shipping!!!!!!!!!!!!! :angry: :angry:

PostPosted: Mon May 07, 2007 4:31 am
by ozzie
Hi All,
I have Chappy's fuel set up and it works great. I used 3 Festo quick connectors, fitted to the fuel cap. When refueling i just remove the lines and move away from the aircraft and fill it. (just in case) Or if i ever have to walk/drive to a servo, i carry a undrilled fuel cap in my stash bag. I haven't got a lot of time on this set up but it already has proved far less troublesome than old primer bulb setup.

I too have found that aviation has become much harder even at our light end.
since 9-11 here in Oz they have introduced about 500 new airport security laws. from photo cards on lanyards to paddlocks on flight controls. can't go here or there. possibly the same drill as the US and Can. This is on top of the new "day to day measures for percieved threats". A scary thought is we do not have a 'bill of rights' to protect the individual/media ect.

The new draft for the new regs., has been released for comment. It looks like the old CAO's, that are basically just exemptions against rule number one, 'thou shall not commit aviation unless one holds an exemption'. Will become LSA that will bring the weight limits in line with that of other countries and allow many now operating aircraft (plastic parrots ect) to operate at their design weights. The lower weight catagories will be lumped into one group labled as Lightweight Aircraft under 280kg auw. I am pushing for a nanolight catagory for those under 80kg empty as per the current powered hanggliders that don't need rego ect. But everyone is screaming for more weight and speed. getting a bit hard to define the line across into GA. The beauty of a Lazair is flying from a paddock and giving it all miss. :D Ozzie

PostPosted: Tue May 08, 2007 10:23 am
by JPXman
geez - here in canada its hardly noticeable, at least out here in the wild west. our strip is 7.1 NM from an international airport and nobody cares. just stay clear of controlled airspace is all you have to do - or get permission to enter without a transponder.

flying a champ is almost as enjoyable as the lazair though, i'm jealous of you chappy! i learned tailwheel in a chief and then spent some hours in a champ (canuck, citab, super cub, scout, L-19, pawnee....) but i like the champ 2nd best next to the pawnee. lazair still is the most fun aircraft i have flown.

sorry to get off topic - as an on topic discussion, is the normal routing for a 185 fuel line totally uphill from the gas tank to the carb?


PostPosted: Tue May 08, 2007 11:59 pm
by Chappy

My experience has been that if the engine has a fuel pump up at the engine (and our diaphragm carbs on the Rotax 185s have a built in pump) then, yes, it really should be routed that way. I know people like to run the line (neatly) up to the boom and across, and usually end up with a horizontal sag along the boom. This allows a high spot that can collect vapor when very small bubbles collect and can create a big bubble that can grow to be a couple inches long. This is especially true in the summer if you have a primmer bulb and/or inline fuel filter, or just vigorously mixed your gas and oil, or taxied around a bunch on a rough field, or have a little moisture in your gas. All these things can make it easier for tiny bubbles to form in the fuel when it's pressure is lowered, and that's what happens to it when you have a high mounted pump trying to lift the fuel way up from a low mounted tank. Then, when you pitch up to climb, this big bubble can escape and reach the carb. The engine may loose power, even stop, especially if you are at full throttle. Even if the engine doesn't stop, the loss of fuel also means a loss of lubricant. Do this enough times and the engine may suffer. Many Ultralights have low mounted fuel tanks and high mounted engines. I had an Avenger (now they are called Hurricanes) UL with a dual carb 503 with a big Volvo pulse type fuel pump just below the carbs. The pump was very strong and the fuel had to be raised up even farther than in a Lazair, and the problem was even more pronounced. Running the fuel line without the sags was extremely important on that machine too.


PostPosted: Mon May 28, 2007 6:34 pm
by daffy1029
Hi all,
I finally got s/n A471 back into the air for the first time again. Haven't flown it since around 1988, and not ever with Solo engines. It was a bit windy, but straight down the runway. I get to the end of the runway and left engine died, when I cut the throttle. I tried starting it up and it started right away. I did a run up, and it seemed fine. So I punch the throttle, and up I went. Went to 700 ft. and leveled off and proceeded to circle the runway (in case anything happens). I am still getting some bubbles in my fuel lines and the engines were not steady on the rpms. I decided to swich on the electric fuel pump, and the bubbles disappeared, making the engines run better. So I still have a problem with bubbles, and I think it has to do with the fuel filter, as it is mounted sideways. You can never get all the air out, so I will mount them vertically and try that next time I go flying. If the filter is vertical, the air has to go through and that should help pump the fuel up better. The landing was ok, but when i turned it around, to taxi back, the wind picked up my tail, and I was stopped on the enclosure with the stick back all the way. I tried a little extra power hoping to get the tail down, but that didn't work, as it pushed harder on the enclosure. I idled the engines down and assessed the situation and decided to shut the engines off. Down came the tail. I started the engines up again and was able to taxi back to the hanger downwind. Jpxman was watching the whole show and told me that all I had to do was push the stick ahead, and the wind would have pushed the tail back down. What a dummy eh? Oh well, live and learn. It was great to get into the air again! Daffy :lol: