Single cylinder OHV - "Snöffy"

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srobovak

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Hi HMEM,


I have been working on this one for over 4 years now and it finally came to a successful end...

After researching numerous builds from other people and combining things together I eventually distilled my own engine design.
I wanted to work in the metric system and also wanted to adjust the size of the model and its complexity to my own demands. As most of these models serve only the purpose of pleasing the builder as they come "alive" I also wanted a design that would suit my own aesthetic ideas of how it should look like.

I opted for the looks of an early 20th century motorcycle single. After about 3 years of irregular work, I had my first test run which was a failure. The engine would not run continuously even though I had a few puffs. I re-evaluated a couple of things and decided to change the cams to milder timing characteristics, enlarge the flywheel, improve the valves and their sealing and also improve the sealing of the carburetor. This work took me about 5 more months to complete.
But the second try was an immediate success. The engine now starts really easily and runs quite well. The RPM range is quite narrow though - it idles at around 950 RPM and reaches its maximum at 1800 RPM.
It also needs some time to rev up and down this range which is due to the large flywheel. I am also pleased with the way it sounds which was also one of my goals.

Some engine details:

- the square design of 25 mm stroke to 25 mm bore
- spark plug ignition using NGK CM-6
- home-brewed stand-alone ignition module using automobile coil
- O.S. 1A carburetor
- running on Coleman fuel mixed with 5% 2-stroke oil
- splash lubrication

I would like to thank everybody on this forum for your time to share this great hobby with others. Special thanks to Terry (mayhugh1) whose posts helped greatly in finishing this project.

Till next time. Cheers,

Branislav

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johnmcc69

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Beautiful engine & it sounds great!

Real nice job!

John
 

awake

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Beautiful indeed! I love the mounting using the curved sections.

Any thoughts about whether you might offer the plans for sale?
 

kuhncw

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You've built a very nice looking engine. I like the low rpm idle. Sounds great.

Chuck
 

tornitore45

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On top of all compliments given by others I should say I never seen an engine with suck a slow stable idle, one can almost count the revolutions.
Great work.
 

ShopShoe

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Congratulations. What everyone has already said. Beautiful, well-thought-out design, Runs smoothly and sounds great. Fantastic low-speed idle and smooth throttle response. I wanna make one someday!

Can anyone give me a hint as to how the name should be pronounced? I'm not good at umlauts.

--ShopShoe
 

peter2uat

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Congratulations. What everyone has already said. Beautiful, well-thought-out design, Runs smoothly and sounds great. Fantastic low-speed idle and smooth throttle response. I wanna make one someday!

Can anyone give me a hint as to how the name should be pronounced? I'm not good at umlauts.

--ShopShoe
The "Ö" is spoken like the 'e' in "her"
 
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dethrow55

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hello that is a super nice build.:) any plans for sale? thanks pm me.
 

Johno1958

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Beautiful engine. Congratulations.
 

srobovak

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I thank you all for your kind words and your interest in this engine.

One of the most important lessons learned is that one must properly finish the 3D-model and all technical drawings before the machining begins. I was impatient and kept changing and adjusting things as I went along. This means that the drawings are inconsistent and include plenty of mistakes. There are about 20 combination drawings and I would have to revisit them all and probably start with updating the 3D-model itself. I'm on a tight family schedule now and can not afford to do this.

Maybe I will revisit it someday and compile the set of drawings that I would feel comfortable about and can make public.


Till next time. Cheers,

Branislav
 

John Antliff

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Beautiful engineering. I guess the large mass flywheel is mostly responsible for the smooth slow running just like the full size hit and miss engines heavily rely on the large rotating flywheel mass to keep going. With a single cylinder engine you definitely need a big flywheel!
 

SteveM

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A truly unique and stunning piece of engineering Branislav, beautifully designed and created. I'd just like to add my name to the long list of people who'd happily pay for the plans if they ever became available.
 

oldCB

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Hi HMEM,


I have been working on this one for over 4 years now and it finally came to a successful end...

After researching numerous builds from other people and combining things together I eventually distilled my own engine design.
I wanted to work in the metric system and also wanted to adjust the size of the model and its complexity to my own demands. As most of these models serve only the purpose of pleasing the builder as they come "alive" I also wanted a design that would suit my own aesthetic ideas of how it should look like.

I opted for the looks of an early 20th century motorcycle single. After about 3 years of irregular work, I had my first test run which was a failure. The engine would not run continuously even though I had a few puffs. I re-evaluated a couple of things and decided to change the cams to milder timing characteristics, enlarge the flywheel, improve the valves and their sealing and also improve the sealing of the carburetor. This work took me about 5 more months to complete.
But the second try was an immediate success. The engine now starts really easily and runs quite well. The RPM range is quite narrow though - it idles at around 950 RPM and reaches its maximum at 1800 RPM.
It also needs some time to rev up and down this range which is due to the large flywheel. I am also pleased with the way it sounds which was also one of my goals.

Some engine details:

- the square design of 25 mm stroke to 25 mm bore
- spark plug ignition using NGK CM-6
- home-brewed stand-alone ignition module using automobile coil
- O.S. 1A carburetor
- running on Coleman fuel mixed with 5% 2-stroke oil
- splash lubrication

I would like to thank everybody on this forum for your time to share this great hobby with others. Special thanks to Terry (mayhugh1) whose posts helped greatly in finishing this project.

Till next time. Cheers,

Branislav

View attachment 111599 View attachment 111600 View attachment 111601 View attachment 111602

Absolutely Gorgeous!!
 
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