Neptune Twin progress

Feb 18, 2020
14
53
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Dakota , Ilinois
Hi all , Boo here . Making nice progress on final assembly of the 1922 Neptune , this has been a build a piece at a time from junk , then hang it on kinda project . I tore it all down , sanded & painted all the parts at an early elementary school talent level ....... then with tin work hanging by wire from the garage door tracks drying & dripping paint I found the old peanut butter jars with thousands of bolts , nuts & little brackets needed to put it back together. In a few ( very few ) cases I even figured out the proper order to re assemble it & avoided the dreaded put on take off repeat 'till you figure out where & how it goes . Hope to have it finished up this week , waiting on a friend that is making me a Brooks style seat cover.
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indian22

Well-Known Member
Dec 31, 2014
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Your Neptune is too cool!! Speaking of which did you solve the coolant flow problem?

Rick C.
 

PeteMcP

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Jun 27, 2017
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Hey Boo, that's what I call progress. Unique, neat looking build.
Well that all came together nice and quick. Kinda like a jump cut edit using the 'here's one I built earlier' format.
 
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Feb 18, 2020
14
53
13
59
Dakota , Ilinois
Your Neptune is too cool!! Speaking of which did you solve the coolant flow problem?

Rick C.
Not solved , but not necessarily a problem ? me thinking is : motor is designed to suck up river water at 90 deg maximum , use it once & spit it out & only at whatever pressure it takes to shove the water back into the river . I am going to keep returning this water to the engine at what appears to be 150 deg in idle testing & at 12 lb pressure or whatever the rad cap is rated for . Dunno if the clearances in the motor are going to agree with the higher temps or if the head gaskets are going to handle the pressure on the coolant side of things ? Someone mentioned restricting the coolant flow to make it spend more time in the rad in front of the fan , but I am running 1/4 in lines so it is pretty restricted as is . I am adding an old small brass fire extinguisher made into another fluid reservoir that holds maybe a qt & a half, doubling current capacity. Will know better when my 300 lb being attempts the first uphill ride ? Good thing its got pedals ! Will update as I work my way thru it . Found an interesting story on line about a guy in the 60s or 70s that ran a 4 cyl german outboard on a cafe style bike & ruled the world in his class for several years , so it can be done !
 

PeteMcP

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Jun 27, 2017
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Yep, never throw anything away. When my dad visited, he used to ask if I was going into the scrap metal business. He was a retired carpenter - and I used to ask why he wasn't in the scrap lumber business, so I know who I inherited the habit from....
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
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Having explored Neptune Twins and best tuned 4hp and your stated mass of 300lbs plus the machine mass.
Something is amiss. At least to me. Carry on Sir. The running product will expand our what is possible list.
I have a 1903 Evinrude Outboard that is not up to the task.
Tom
 
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Feb 18, 2020
14
53
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59
Dakota , Ilinois
I'm using a belt torque converter , and there are pedals , and I live at the apex of the highest hill in town , and gravity ? I can surely coast down to the gas station spewing evil , noxious , 12 to 1 2 cycle fumes ,belching and farting , ( I think the bike may make some noise too ) all the way ! Roll up to the Casey's station looking REAL cool , melting the hearts of all the hot grandmas , then call my bride to bring the pick up to haul me back up the hill for round 2 !
I remember reading that the real board track racers were 1000 cc and 8 hp in the early days , so maybe 4 horses will do the job , certainly as much as a moped has ?