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""Poppin" engine at 150% size, work in progress...
Posted by ShadetreeMotorcycle on 06 Mar, 2021 22:08 -
I have avoided sharing this as it is unfinished and in quite a raw state at this time. I dug her out tonight dust bunnies and all because some recent posts about PMR flat belts reminded me of her and I added the cooling fan of my own design to the build driven by PMR belt.
Machined Everything from billet with the exception of fasteners and the 5 piece Crankshaft I used store bought Dowl pins (to construct) as they are hard/smooth/straight and a pleasure to work with.
The "back" story on how this little engine came to be was my shop was slower than I had ever seen and my Foreman was tired of me pestering him for more work....he finally said "go look busy and try not to build anything illegal"
I said: "so....automatic weapons are out....everything else is fair game??"
He said "Sure!"
The rest is history!
Anyway...the free Poppin plans on web are quite small so I 150% sized, added cooling fan and ball valve on top to improve performance. The cooling fan is made one piece from aluminum sheet...the guy benched next to me saw me building it and said a homemade fan that small would not blow the hair off a frog....So I chucked it up in my 20,000 RPM die grinder and blew all the paperwork off his bench from 15 feet away!
The oil cups where not on the plans but I added them, all functional. Have run MM oil in the crank cups and it works but a little thin. Graphite powder only in the big cup on Cylinder.
The fan spins nice driven off the big flywheel but really makes the burner flame dance to much. I have plans to make a shroud like I have seen on air cooled hit and miss engines. The green paint on one flywheel was only a test to see how it looked, not sure if go bead blasted or full polish or paint yet. The Poppin gets its name from the delightful engine sounds it makes...ohh yeah...thats the other reason I have not shared this build is because Nick will likely want me to post a video of the sounds it makes and I still don't have YouTube.
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Ya' gotta' get a YT account!!!!!!!
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I have not shared this build is because Nick will likely want me to post a video of the sounds it makes and I still don't have YouTube.
😂 😂 You’re not wrong
what’s stopping you??
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Some very nice machining work there. Looking forward to seeing this finished.
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I have not shared this build is because Nick will likely want me to post a video of the sounds it makes and I still don't have YouTube.
😂 😂 You’re not wrong what’s stopping you??
Nick, I am kind of glad you asked my friend!
A small portion of the reason is I do all my posting from my highback comfy chair way out in the woods in some remote portion of Michigan where cell phone signal is Much worse than iffy. What happens is I get half way thru an account set up and signal goes completely dead and I have to start all over....I can solve this problem by driving my phone out to civilization and get a better signal.
The Real reason is someone suggest to me that A YouTube competitor of video hosting sites may be easier to sign up to....I started the sign up process during our very recent Presidential election and was warned during sign up that if I posted any Video content that was favorable to our "then" Conservative President that my account would be frozen all assets seized and held criminaly liable for my unwanted views! I am paraphrasing of course but that was the general gist of message conveyed to me by THAT video host...I do not want my little engine thread to become in any way political but I have not quite worked up the Heart to go see how bad YouTube video posting policys are (I will go look).
Thanks for the kind words on my project...I built it before finding this forum and had not been around Steam and hit and miss engine guys before.... now the oil cups and a few other things look crude to me but I can spin up some nicer ones! -
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A teaser video until I get my youtube going...this one appears built to print... bone stock and 1 to 1 size. I deviated quite a bit on materials selected from the scrap bin so no shiney brass flywheels and my engine has a bit deeper voice at 150% size.
I had originally posted it as a 200% build but now seeing this stock video I recall mine is only 150% not 200% they say the mind is the Second thing to go....
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All makes sense and am glad I have as fast of internet as I do. I believe Jim used to have to start his youtube uploads, go to bed and by morning they’d be just finishing up
You do nice work, so if you can’t get videos online, keep sharing the pictures
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The fan side, the fan axle is long as this is where I was at when production ceased. It was fun to make the one piece fan base and is independent of engine so can be removed without a trace....
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Even unfinished, it sure looks nice!
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All makes sense and am glad I have as fast of internet as I do. I believe Jim used to have to start his youtube uploads, go to bed and by morning they’d be just finishing up
Just reading that gave me a shiver up my spine about how bad and slow our internet used to be
We are now on what is called Fixed Wireless and we have what looks like a little satellite dish on our roof that is aimed at a repeating tower some kilometres away on top of a hill.
Its gone from taking up to 12 hours for a few minutes of standard definition video to upload to around 10 minutes for a longish high definition video to upload. -
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There is a steel ball in what looks like a chimney on my Poppin engine, this was not on the plans and added by me, it is a self made ball check valve of sorts that improves the efficiency of the engine, these type engines often employ a slide valve and slide valves can leak if not really well executed, this is one of the reasons flame lickers can be troublesome to tune. What happens is slide valve goes open and piston travels towards bottom dead center and draws in hot air then slide valve closes and air is cooled and makes vacuum to suck piston towards top dead center...if slide valve is nearly perfect seal this can be a fairly strong power stroke...however...what happens in real life is often the slide valve leaks badly and the engine will not run..if it leaks only a little the engine will run but not make much power...in this comon situation as the piston nears top dead center it should still be under vacuum or negative pressure but it is all to common that the last roughly 1/3 of the up "power" stroke the piston is actually making a little compression or positive pressure! (slide valve leaks for the entire time it's closed)This is very bad as it is trying to stop the engine from running rather than making power...the engine "can" sometimes still run in this bad condition if the power stroke was strong enough to get the flywheel moving fast enough to get the piston pushed thru to the nest cycle...enter the ball valve fix!...on the down stroke the ball is sucked down to a tapered hole to make seal and engine is happy...then on the up stroke as the air starts to turn from negative to positive pressure near top of stroke the ball is not heavy so the ball is blown up and the positive pressure is vented so as not to hamper piston power stroke. This simple system is said to improve power by approx 1/3 or in the case of a badly leaking valve it can turn a non running engine into a running engine.
Some might view it as a band-aid as the real problem is a leaky slide valve.
I view it as it adds visual intrest to the engine! It is also fun to look in the stack and watch the ball jumping up and down...it sounds like I am popping popcorn made from ball bearings.
Normally there is a threaded screw mounted above the ball to control how high the ball jumps...this is to tune for best running. It is important for the ball to jump quickly to let the positive pressure out...but equally important to get the ball back down quickly to seal for the next cycle.
I tried a threaded screw but it killed the smoke stack look so I came up with the little metal screen over the top...looks neat and offers a cushion stop for the ball and much more quiet popcorn sound.
This got to be long...hope I did not put the experienced guys to sleep or worse yet make them mad.
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