Homemade 4-Stroke Single

[boogerballs]

A friend of mine who is a vintage/race car fabricator as well as having the prestigious title of the world's fastest 50cc streamlineris at it again. I just left his shop and am still amazed at what he's accomplished. He took a Honda crank, a VW piston, barrel and head and a Tillotson carb. He heavily modified the head, made his own rocker assembly, and is using an atmospheric intake system (no intake pushrod, just a spring) that uses the vacuum created in the combustion chamber to open the intake valve.
He completely fabricated the crankcase from an aluminum tube and a couple of chunks of aluminum billet. Well he started it by hand and it started real easy. Since he hasn't balanced it yet, it shakes and vibrates quite a bit. Here are some images.

 

[Al.Fisherman]

When I see posts like this, the way it's titled as "Made" I automatically throw up the BS flag. Let me pull it down real quick...One heck of a job.

 

[vazfx16]

now that is art

 

[ibdennyak]

Outstanding!! I have nothing but admiration for people who do projects like that. I have a few friends in Wisconsin the "restore" the hit and miss engines. By restore I mean they fab their own rings, pistons etc....whatever the engine needs. They are a fascinating group of people.

 

[Turtle Tedd]

This is the kinda stuff I like...focused ,obsessed ,genius at work....

 

[Mountainman]

wow ---------- yes ------------ fine homemade

would that THING look so fine on a motorized bicycle ??

man oh man

MM

 

[mlcorson]

I admire a person who can, just for the fun of it, create a vision and then overcoming all obstacles, summon all his/her powers and skills to fulfill it. Amazing work.

 

[motorbikemike45]

That is sweeeeet! The atmospheric intake valve is an old idea that worked fairly well in WWI fighter planes. The Gnome Monosoupape (one valve) rotary engine is what I am thinking of. The atmospheric valve does limit power output compared to a cam operated intake valve because the valve doesn't open as long or as wide as a cam operated valve and valve timing is severly limted.

 

[ibdennyak]

That is sweeeeet! The atmospheric intake valve is an old idea that worked fairly well in WWI fighter planes. The Gnome Monosoupape (one valve) rotary engine is what I am thinking of. The atmospheric valve does limit power output compared to a cam operated intake valve because the valve doesn't open as long or as wide as a cam operated valve and valve timing is severly limted.[/QUOTE

Yup, same as many of the hit and miss engines. Also contributes to economy. Some of them used a governor to hold the exhaust open to limit speed. With the exhaust open, there was no vacuum to draw in fuel/air until the engine slowed down enough. Not terribly high tech......but effective.

 

[boogerballs]

I know John was trying to keep the power down on purpose and the atmospheric intake did its part. Since the VW barrel and piston was about 300-400cc at its stock stroke, he cut the connecting rod in half and joined it with the Honda 125 two-stroke roller bearing crank after cutting that connecting rod as well. He joined the two rods together with the resulting diplacement at around 250cc. The carb is tiny as it came off a 50cc two stroke engine. He figures it's going to produce about 2.5 horspower. I've included a somewhat blurry picture of the other, non-modified, half of a VW head. The other half is what he trimmed off lots of fins and such.
I watched him experiment with using just one ring versus two rings on the piston, since one didn't produce enough compression for him. He also switched out the atmospheric intake valve spring with a lighter one so it might idle better. Just amazing!