79cc Sportsman Flyer build

fasteddy

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Feb 13, 2009
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Tom,
The yard is my sister in law and brother pride and joy. I'm the natural habitat type of person myself.
I have a friend who has a 5 acre piece of land and he had his house in the center of it with lawn on the rest of the property. It isn't very often that I go to see him that he isn't on a lawnmower cutting grass as happy as if he was in his right mind.

Steve.
 

Tom from Rubicon

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Apr 4, 2016
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So today I was driving Miss Daisey (Mona) to get a Flu shot, unfortunately they only had the under 65 brand. Better than nuthin. Post inoculation, day warmed up with a SW wind, Maples and such are still full and colorful. A few people really get into the Halloween mood here in SE Wisconsin. This is an example.
Tom
 

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indian22

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Dec 31, 2014
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So today I was driving Miss Daisey (Mona) to get a Flu shot, unfortunately they only had the under 65 brand. Better than nuthin. Post inoculation, day warmed up with a SW wind, Maples and such are still full and colorful. A few people really get into the Halloween mood here in SE Wisconsin. This is an example.
Tom

This guy is a hard core daily rider with low index numbers. Lean to the bone!

Rick C
 

indian22

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Dec 31, 2014
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What a great project! I've mentioned in previous posts growing up and having a neighbor who restored and collected all manner of steam powered tractors and assorted agriculture coal fired, field tools which he frequently drove around the neighborhood; and for a small boy they were magical fire breathing steam and noise producing miracles.

Rick C.
 

Tom from Rubicon

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Apr 4, 2016
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I'm kinda like Rick, right now. Waiting on parts. Billet flywheel and 18# springs.
One little machining detail on the head needs be taken care of. At 6:41 of;
Shane machines down the protruding part of both valve guides in the ports using a special to me 6mm piloted counter bore that I don't have.
Plan B. The valve guides are press fitted into the head, so I carefully drove them flush in the port chambers.
Made the port polish much easier overall. With one caveat. The added length of the intake valve guide in the rocker arm chamber will not allow the intake valve seal to set at the designed height.
The valve guide will be milled and deburred lightly. Done so to allow valve seal a proper fit.
Tom
 

PeteMcP

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Jun 27, 2017
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Cool vid link Tom. Save a bunch going the DIY route. More fun that way.
That electric mini Bugatti in the video's bonus footage looks really neat. Always hankered after building a cyclecart. Something like a half scale Morgan 3 Wheeler - with leccy power.
 

indian22

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Dec 31, 2014
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Tom I'd suggest this video to any not familiar with small engine machine work for heads. It may come as a surprise to many that basic hand tools are utilized for most of the mods. The mill was used only for fly cutting the head. A drill press was employed to mill thebottom of the valve pockets and this plunge cut with an end mill puts no pressure on the press than the machine was designed for on the Z axis. Side loads on the X & Y are what the drill press bearings are not equipped to handle well or for long.

It's a good video despite what I posted earlier about carb trade secrets he mentions then goes on about the alterations made by AKG on the carb for a few minutes, oops! Cart guys flow test carbs all the time the fun way that works....on the track.

Pete I'd like an adult version of the Bug or a Morgan as well really cool stuff.

Rick C.
 

Tom from Rubicon

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. A drill press was employed to mill the bottom of the valve pockets and this plunge cut with an end mill puts no pressure on the press than the machine was designed for on the Z axis. Side loads on the X & Y are what the drill press bearings are not equipped to handle well or for long.

Not milled, piloted counter bore.
Tom
 

Tom from Rubicon

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79cc Predators are alleged to produce 3hp. But it can be increased to it is claimed optimum AGK claims to 5 to 7 horse power?

The total weight of a Sportsman Flyer 80 is not specified but they are a weighty machine for reasons of safety and durability. We have roads in the Kettle Moraine area of S.E. Wisconsin that going East West take the Eskers at a right angle = steep 30degree 200 ft climbs. Flyer80 struggles to mount without a good running start stock engine. More power is the ticket!

You can send your 79cc Predator engine head to AGK, get a .050” head deck, to up compression, and port and polish, adding stronger 18lb valve springs are needed if you remove the governor.

19mm Mikuni clone carb is a given. Stock Predator carbs do not have flow anywhere equal to a 19mm Mikuni clones.

The only other extreme and costly mod I am doing, is replacing the cast iron flywheel with a ARC Racing billet aluminum flywheel. Keyway cut to a extra 4 degree spark advance totaling a 28 degrees of advance.

Today the ARC 6671 flywheel came by post. It is a CNC machined thing of beauty. Embellished with engraving which will
be unseen as I will be using the pull start blower housing this time around to take advantage of the finned flywheel.
Couple of poor photos. I got a pro photog buddy. Where is that rascal?
Tom
 

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