speedracerntrixie

My Feedback: (29)

Just like inside the engine the gas needs the correct ratio of oxygen to ignite. I doubt the muffler has enough oxygen within it. We all drive cars and trucks that have a brushed electric motor spinning away submerged in our gas tanks.

jasona

I'm blown away by the response here, you're all very kind, thank you so much!

I'll take some pictures when I can (hopefully Tuesday)

Tried RichardGees start technique: I printed it off and took it with me! The engine didn't run, but it was definitely more responsive, interesting, thank you!

In response to speedracerntrixie: No, I never needed to use starter fluid on the test bench.

There are definitely no choke plates!

ec121: It's a Meiss engine: Fairly obscure German make: http://www.meiss-motoren.de/Reihenmotore/45_R/45_r.html

p39

My Feedback: (5)

I've been trying to see if someone mentioned that if you are trying to start at low throttle, make sure your throttle setting is off of closed. (slightly open) I believe one post mentioned low throttle and two clicks up. Make sure the butterfly is not fully closed. Also someone mentioned the small (10cc) Evo engines needing muffler pressure... that is true. They do not use a pumped carb. Good luck!

gwweber

My Feedback: (24)

what oil are you using and what is your mixture.   Problem may be that the engin is running rich.

a70eliminator

I'm thinking the diaphragm pumps are recieving pulses from crankcase pressure in opposing sequenece, therefor you must utilize a seperate supply to each carb rather then you T that is there now, the pulses may be conflicting cancelling each other out.

jasona

WHOA! Awesome theory! That's a revelation! Coincidentally, having just tried a couple of other things that didn't work, next I was just about to embark on the project of giving them a separate fuel line each rather than the T-piece situation: Some new Tygon arrived today! Ah, but then it worked with this set-up on the test bench. Still going to try this as a next step though: It's struggling to get fuel through to the front cylinder. Rear cylinder gets wet easily (wish my wife did too)

gwweber: It's 50:1

spaceworm

Sure hope your wife never reads RCU

av8tor1977

My Feedback: (6)

Get wet easily?

Tee hee.... Mine used to, then she didn't, then she left. Bummer. Life goes on.

AV8TOR

raptureboy

Maybe your not priming her rightI can't believe these carbs have no chokes. Looking at the pictures they look like they do.

av8tor1977

My Feedback: (6)

Naw, that's not it. She lost her x drive after the baby was born.

We still really need pics of the OP's setup to be helpful here....

AV8TOR

rexbirk

Any inline two stroke multi cylinder I have ever seen in the motorcycle world have the crankcases of the cylinders seperated by seals. Otherwise unless the pistons fall and rise in unison the crankcase fuel mixture would be flowing back and forth and not flowing up the ports into the cylinder. I believe his problem deals with no crancase pulses getting to the carb so no fuel pumping action.

av8tor1977

My Feedback: (6)

Yes, inline two strokes need a sealed crankcase, dividing the two cylinders so that they can pump even though the pistons are going up and down opposed to one another. So the pulse line with a "T" should work, though it's probably not the optimal setup; separate lines to each carb.

But, we are all really just guessing without being able to see the setup in pictures.

AV8TOR

jasona

Hi Guys,

So last night I started the job of re-plumbing the tubes to the fuel tank and I think I found the problem! (First picture)

It's a bit blurry, but it's a picture of a melted fuel pipe! It had to run near the exhaust and although I went to great lengths to protect everything with motorsport-grade heat shield or even running things through a silicon tube as conduit, it still managed to find its way into contact with the exhaust and start melting. Blowing through it, fuel could still get through OK, but there are tiny holes in the melted bit, so maybe it was letting air in. This time I'm taking the new fuel pipes on a completely different route well away from the exhaust.

To get access to the piping, I removed one of the carbs (pipes and wires had to be put in before I installed the engine and exhaust: Now everything's hidden by the engine and exhaust and inaccessible and doing this stuff is a real fiddle). It turns out they're Walbro carbs (2nd picture). I don't see any moving choke plate on there, or am I being really thick? (I have the misfortune to be British: We say "thick" instead of "dumb").

I've got the new fuel pipes threaded through the airframe, I'm now off to connect everything up and see if it works! I'll report back!

azalner

My Feedback: (8)

[quote]ORIGINAL: jasona



"To get access to the piping, I removed one of the carbs (pipes and wires had to be put in before I installed the engine and exhaust: Now everything's hidden by the engine and exhaust and inaccessible and doing this stuff is a real fiddle). It turns out they're Walbro carbs (2nd picture). I don't see any moving choke plate on there, or am I being really thick? (I have the misfortune to be British: We say ''thick'' instead of ''dumb''). "

I must be thick as hell because there is no choke plate in that photo.

azalner

My Feedback: (8)

No choke plate explains why you are playing hell getting gas up to the carbies (holes in the lines doesn't help). You might consider replacing the carbies with these:


[link]http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXANVR&P=ML[/link]

Good luck!

kmeyers

No choke, one needle and I bet he paid top dollar.

I'm so glad I'm not a Warbird guy.

jasona

Yep! Cost an absolute bloody fortune! I have to get this thing in air though: It has massive emotional excess baggage attached.

jasona

Right, just got in from the workshop having finished the re-plumbing of the tank. It took about 2 hours to get one of the carbs back in: Made me wonder how I got it out in the first place.

Two clunks inside the tank now, each carb now has its own dedicated fuel line.

No muffler pressure.

T-piece on one of the fuel lines for fuelling.

Now then, the routing of the vent pipe: Back over the TOP of the tank and then out through the bottom of the plane, right?

The fuel pipes are well away from the exhaust and well protected.

Once it was all done I fuelled it, choked it and both carbs were getting fuel through, so all looks fine. Consequently, I was DYING to try firing it up, but by the time I'd finished it was nearly midnight, so I don't think I would have been too popular with the neighbours!

I'll try it first thing in the morning. If it works, then I'll be angling for a short-notice test flight, as I'm supposed to be displaying it to the family on Sunday!

speedracerntrixie

My Feedback: (29)

Don't rush getting it out and in the air. Go through your starting sequence a few times at home and make darned sure the engine behaves predictable. I have seen way too many airplanes lost because they were put into the air because the owner was convinced his issue was fixed.

jasona

You're so right. I know it's unwise to try and do anything aviation-related to a deadline.

Is that right about the vent tube though?

a70eliminator

If you did the in tank portion of the vent pipe properly then it doesn't matter how you route your vent tube.
With your fill T tied in like that just remeber to have the carbs fully closed or you'll flood the carbs with fuel while re-fueling.

jasona

Right, thank you.

Just tried it: It fires up and runs instantly, but won't run right. It's 2000 rpm short of what it was and I'm trying to work out if it's just running on one cylinder.

I'm off out to try it again and try and work out what the problem is.

spaceworm

Walbro carbs do not allow fuel to pass with the engine not turning over (either by hand or when running). So, flooding while filling is not a problem. With glow carbs, flooding could be a problem when filling the tank, as there is no vacuum operated inlet valve in the carb.

jasona

Ahhh, right. Good.

It's running fine now: Took the plugs out, found the front cylinder flooded (don't know why, the T-piece for fuelling is on the supply to the rear cylinder, plus what you said above anyway).

Hoping to test fly tomorrow: It crashed on its first two maidens, here's hoping for 3rd time's the charm!

jasona

Test flight today: It crashed again. Gutted. That's the third time.

I feel that I can’t give up on though it as my late father wanted it to get airborne, so I plan to repair it over the Winter with a view to trying again next year.

I do want to thank everyone on this thread though: I was blown away by, and hugely grateful for all the input from the very kind people on here who invested their time into trying to help me out.

The comments were really useful and gave me some good ideas along the way.

Thanks again to everyone, you're all great!