2 Cycle Engine from Bar Stock

[Brian Rupnow]

Lohring--Thank you for an incredible piece of work.---Brian

 

[canadianhorsepower]

As promised, I quickly (for me) drew up a modified version of the Wombat. I did not draw a carb or ignition system, just the internal parts. You can use the Wombat systems or a Walboro WT-157-1 and a CD ignition. I included a simple block crankcase as well as a more Wombat like version. Plates that I didn't draw cover the transfer passages in the block. I think this is about as simple as a two stroke gets, but I assumed some engine building experience. If anyone actually wants to build one, I would be glad to go into more detail. The drawings haven't been checked so they probably contain errors. I would draw an assembly as the minimum check.
Lohring Miller

Thanks for the drawing, quite a change from the original. I was checking the drawing closely because I would be interested in building one. Correct me if I`m wrong but the big end of the connecting rod give a radius of 1/4 and hole diameter of.312 the small end 7/16 radius and hole diameter .250

thanks

 

[petertha]

eyeballing the pic, guessing 7/16 should be 'diameter'

 

[canadianhorsepower]

eyeballing the pic, guessing 7/16 should be 'diameter'

that's what I came up to

it gives the same wahl thickness .1875 at both end Thm:

but it could also mean that the edge have a radius of 1/4

cheers

 

[ozzie46]

I believe the circles with the lines thru them are a drafting convention meaning "Diameter".
At least that's how I have read them.
Ron

 

[canadianhorsepower]

I believe the circles with the lines thru them are a drafting convention meaning "Diameter".
At least that's how I have read them.
Ron

I know that but read the plans and they don't match

 

[Jasonb]

Should probably have been 7/32" R on the plan which would give the 7/16 diameter

Luc wall thickness will be 3/32" not 3/16"

 

[canadianhorsepower]

Luc wall thickness will be 3/32" not 3/16"

Jason

.438-.250=.188/.0625=3 and that would be 3/16

or what did I do wrong

 

[lohring]

You are right, it should be diameter. As I said, the drawings haven't been checked. I bet there are more mistakes. Assemble the parts in a drawing to be sure everything fits.

Lohring Miller

 

[Jasonb]

Jason

.438-.250=.188/.0625=3 and that would be 3/16

or what did I do wrong

You forgot there is only half the 3/16" on either side of the 1/4" hole which means 3/32" wall thickness

0.188/2 = 0.094

 

[lohring]

A final note:
This is a lower cost series of programs for two stroke porting. Some of the relationships are empirical but are based on decades if experience. I'm not sure how they would apply to really small engines, but they should be a good guide. Port time area calculators and port height versus angle programs apply to all two strokes.
http://www.porting-programs.com/

Lohring Miller