A bit more on a few mixture conditions and how to recognize them:

Any normal gasser runs optimal basically at the brink of lean ignitability limits.
The following numbers are valid for evaporated fuel only: Below a certain fuel/air ratio, around 15:1 mass/mass, the mixture simply refuses to ignite, and the engine dies like (quite literally) hitting the ignition switch.
Optimal ratio is about 14.5:1 and spluttering rich is at about 13:1, any richer than that and the engine is "flooded" (even if there is not really any liquid there) and the engine shuts down as well, but usually a bit more gradually, starting to misfire more and more before stalling.
In these running conditions (100% evaporation of the fuel) the engine runs virtually smokeless regardless of oil content of the fuel, and the oil rresidue from the exhaust is at best a bit discoloured, maybe resembling black, but a bit of that oil on the fingertip should show a fair bit of "opacity" and still be liquid instead of "sludgy".
The fuel being all vapour, the remaining droplets are near 100% oil, and will not really take part in the combustion, not generating heat, therefore remaining relatively very clean and "cool".

Things change when atomizing is (very) poor... then it is possible that the absolute mixture (liquid fuel included) is 13:1 but tthe vapourized part of the fuel still can be at, or leaner than 15:1.
In that case you have the strange phenomenon that the engine runs as if it is lean (liquid does not take part in combustion until AFTER ignition occurred, and it is the moment of ignition that is responsible for how the engine APPEARS to be running), but belches out blue smoke and a relative lot of black crud from the exhaust which is a clear sign of rich running, and will immediately die if the needle is set even the tiniest amount leaner. It is this behaviour that you will typically see when NOT using the solenoid. Even regular Walbros do this. It is caused by the fuel coming out of the jet(s) in an uninterrupted outflow during the induction stroke. The inrush of air will "atomize" the fuel by sheer velocity, but the droplets are rather coarse and big.
Now what happens is that en route from carb to combustion chamber, the fuel evaporates "slowly" and the shrinking droplets wil be relatively rich in oil and poor in fuel.
These droplets do NOT take part in the ignition part of the combustion proces, but once ignited, these droplets will start taking part. But since the vapour/air mix was near spot on allready, they burn in a low oxygen environment, thus burning slowly and very sooty,and emitting a lot of superheated, soot polluted oil.

Now you will never achieve 100% evaporation, not even using the solenoid, but it CAN be very close, especially in fourstrokes, since there is virtually no burnt gasses remaining in the combustion chamber during the scavenging cycle. 2Strokes will always show a tiny bit of smoke, but it can be so faint as to be on the brink of invisible.

Jim, I sent you a PM

Good stuff Bert, thanks.
Meanwhile, I have figured out what S2 does in RaleighCopter "Gamini" set up. I just had to give myself time to think it through (mostly unconscious, which is how I process information like this most of the time.)
It's exceedingly simple in fact; why I did not understand it to start with is a testament to my limited cognitive abilities!
I will post back when my replacement hardware arrives.

Jim.

Some of you might remember back ways I was working on an idea to try a "walbro" style pump and regulator with our solenoid setup and I had started machining a unit.. lots of complicated machining.

I recently discovered that the WYL rotary carbs could be had on amazon for about $20 as a clone. Bought one and an extra gasket set try a little experiment. By Machining off the "extras" and a bit of ingenuity I have a test model with very little work. I ended up using an actual Walbro WYL I had for parts as the Chinese clone has a "high speed" needle and is not "fixed" like the original WYL's and I might try a few other experiments with it.

Here is the result . Planning on getting my original 25cc super tiger conversion back on the stand to try this out. This will feed into the "no Needle" carb and be modulated by the solenoid as per normal process.

Chris

https://cimg8.ibsrv.net/gimg/www.rcu...628bb932d.jpeg
https://cimg9.ibsrv.net/gimg/www.rcu...ae185cb6d.jpeg

Mounted up….
https://cimg0.ibsrv.net/gimg/www.rcu...a12879b48.jpeg
https://cimg1.ibsrv.net/gimg/www.rcu...2d160641d.jpeg

So basically, you made a pump-regulator unit to combine with your Throttle Body set-up?

Should work like a charm, allowing for free location of ful tank, but doubtful if the actual engine performance will change much, given that the regulator only allows fuel in at atmospheric pressure (AKA still depending on intake vacuum for actual fuel delivery).

It would be interesting to see if you can set the regulator up for an offset positive pressure (say, 0,1 bar) and run a larger intake Throttle body and increas performance that way?

Yes Bert, Exactly... The configuration of the WYL carb makes this was as they are both stacked on the same side of the carb.

Installing on a known "good running" setup to be able to start experimenting with the setup - Your correct that it will be "atmospheric" feed but a small spring load on the diaphragm could change that. My custom made regulator cover has provisions already for an adjustable setup.

Thoughts are this would allow for flexibility in tank location as stated, and no need for muffler pressure or a Crap trap. Will keep you all posted.

The "Clone" WYL's have a high speed needle valve that's in the right place in the system (and casting body ) to possibly allow of the install of a "relatively easy" solenoid adapter. That might be my next project. the rotary design would allow for adapting to many engines.

Nice work, Chris. As always.

Hi,
i start the engine this afternoon, atter 2 hours, i get a first start ! now i start it again but bubble start to appeared after one minute between the valve and the needle then the motor stopped. i'm going to change durit this week and try again

Please get your postcount up, so you can post pics and videos. That way we can help you better.

Well.... It Works....

Very quick run to see if I had everything hooked up right - Very quick tune and can tell the fuel pressure is down from the muffler pressure setup as the top end is leaner than before. Will start playing now with the setup. Fuel feed is solid with the pump.

Short clip as my hands were cold and my receiver battery was giving up - Dead and cold...

Not too bad of a start on a new pressurized system.

Wow, cold and snow in Saskatchewan already? We're sunny and 20°C here.:p

I use the exact same vintage B&D Workmate for my engine test stand. :)

Turned nasty yesterday Lonnie and first snow .. Was nice until then which is "bonus round" for us - Suppose to warm up again this week a bit.

This one was my Fathers - One of the originals - Lots of "work" been supported by this one.

Some years back I cut down a discarded Walbro carb to make a stand alone crankcase pulse powered pump for uses unrelated to this thread.
It worked fine, but did not have a regulator. It would be possible to make both from scrap, but would not be as neat looking as yours.
Well done,

Jim.

Hi,

I will write more post (how much to send video?) i change all fuel line with good pipes and no bubbles and now i get a10 minutes run next try tomorow.;)

I believe 10 posts are required to attach files.

thanks Glowgeek, tree more to go.;)

That sounds like a winner!

SO I got a chance to sneek to the shop and do a little experiment... Made up a quick cover for the Pressure regulator with an adjustable spring "preload" to set the Pressure output. Came up with a way to bench test with air and set it to .8PSI (.055Bar). Quick bark up and "magic". Only ran at low power to keep the neighbours happy so only set the bottom 4 or 5 points but the response was very good and Idle has never been better. Will need a full setup and a good test but it looks really promising. It is really acting like fuel injection now.

Might have to Squeeze the fixed jet a bit as the lower half of the curve is low - Didn't set anything above 1/2 throttle and at one point of the video I go past my "set range" and it goes very rich very quick as the old setting were still on the curve there.

https://www.youtube.com/watch?v=vSEp...ature=youtu.be


https://cimg5.ibsrv.net/gimg/www.rcu...f34f59911e.jpg

WOW! Dammit, I had not expect that to work THAT well....

VERY curious to see that thing run at full chat and through the entire throttle range.

How is the starting? I mean, from a stopped positio, all parameters being zero, any trouble getting it primed and running?

I don't see this yet bing applied to real small engines still using the stock carb, but anywhere your Throttle body design can be used (.45 and up, I guess), this set-up might allow for humongous air intakes and lots of power.

The setup does not seem to be too bulky either.

Hats of to you, Chris! You did what I actually held for totally impossible: TRUE EFI, with pressurized fuel injected into the air intake, for a hobbyists budget.

You and Me both Bert... Still testing to do but the quick run was a "wait a minute" moment where everything seemed to work as desired. Adjustments were very positive and you could tell the engine was being "fed" rather than drawing fuel.

Starting was very good - the pumping motive is very good and even with empty lines they are filled in short order. Air works out fast. You can see fuel is being "supplied" rather than drawn so flooding might be a possibility and I'm assuming the Pressure regulator Cavity would "empty" when shut down now, into the carb, but no adverse issues were noted yet. Turning the regulator into positive supply also allows through flow when at rest, which will allow the fuel to drain through the system if the level is higher than the carb jet but that's a normal issue for us. Tank location should be lower than jet and that's not an issue with the fact the pump is there. The solenoid also allows for flexibility in "wide open and Shut off" settings (on a switch?) which allows for priming and flood clearing.

I really liked how the Air pump feed worked, but as you noted a ways back - that system was too complicated and added another couple layers of complexity. This one is relatively simple (and cheap) and seems to allow for some flexibility in supply pressure. It's relatively compact but as noted will probably be better adapted on bigger engines. We also must get it in the Air to really determine how it will work. With one working I can try to apply it to different engines and setups to see how they react.

I have another WYL clone inbound to make another pump - This one was $16 CAD on Amazon Prime. The economics are right on this one. Less than 1 hours work to convert.

Hi,

I made a video of the 1st start tonigh, after several attemps with gas at 50% with no result:(, i start the motor with the carb almost closed with the needle closed as much as possible i can speed up to 20% for the moment. is it the good way to do it ?

video
 

here it is it's a little dark over here

Yes, that is the good way. Start the engine, increase as far as it will go, then open the high speed needle ONE click, and carefully increase throttle again as far as it will go. Repeat until you have full throttle..

Thanks Bert,
I'm discovering gas engine and it is very interesting ! i will start to open the needle tomorow