V-Twin 100cc Design & Build

The much more substantial roller rockers in the Stride design would help a lot, though guides seem to be stronger than I thought they would be

Cylinder head altered a little, increased height by 2mm which allows better sleeve support and also slightly larger fins.

Hi Niels, yes balance will be via all rotary and 2 times half reciprocating mass.I'm pretty sure I have enough space to do this as there will also be the rear crank web. Of course it will not be based on volume as you note above but mass, with the steel of the crank web having a greater mass per volume than the lighter mass of the piston.

Another good think about Autodesk Inventor is that it calculates mass and centre of gravity of all parts based on material, so I will be able to use this rather than trial and error balancing.

Craig

Some more work on the head to change the inlet/exhaust connection. I now have a plate connection which will allow me to easily make the manifolds that will be need to be bent to shape to suit the cowl. Manifold will be copper, silver soldered to flange. The lot can then be chromed.

This is a great project, looking forward to seeing it all come together and running.

To give a rough idea how the engine will fit in the cowl. The exhaust manifold will wrap around the outside of the cowl curved to the rear.

Ignore the outlet on the other side, I now need to mirror both the cylinder head and cylinder for that side.

Craig, unless you particularly want chromed exhaust stubs you could solder them up from stainless steel and polish to your desired finish.

Jason, have never tried silver soldering stainless, but could be a better idea than having to rely on external chrome plating. Also like to try something new.

Not really any different to soldering steel, just use HT5 or Tenacity No5 flux which removed the chrome oxide layer.

Slower progress now that I'm back at work.

Checked the counter bore depth needed for the sparkplug. I am using a small sparkplug type (same thread as a glow plug 1/4x32).

Also realised that the spark lead would foul on the edge of the cylinder so have reduced the spark plug angle to 15deg and also chamfered the fins to give clearance.

You can get some much neater and nicer looking plug tops than those Rcexl ones

yeah, they are a bit plain, but what came with the unit. Will consider changing them but that's a long way down the track.

started to make some chips. Cylinder No.1

2.5" HE30 barstock, machined down to 62.5mm OD. Fins are 1mm width with 2mm space, 7.5mm deep.

What type and size plane are you building Craig?

Roger

Rodger, I'm drawing up plans and have it half cut out for a 1920's style racer. Its a mix hybrid between a Gee Bee R3 and Chuck Gratners Riley B design. Wingspan 100", target weight around 14-15kg

parted off overlength, reversed in chuck and faced off to length.

move to the mill to drill the bottom set of holes for bolting to crankcase and milling the octagon faces.

all that remains are the top set of holes, but think I'll leave these until later as they are non-symetrical and also mirrored for each cylinder head bolt pattern.

Hi Craig, this is a lovely project and superb CAD drawings, especially the fully rendered 3D images. As an engineer and keen RC aircraft fan I'm looking forward to seeing this running and flying. Do you use Inventor in a professional capacity?

Graham

Thanks Graham, I am an engineer by trade but in a different field (building services - heating,cooling, ventilation, sustainability etc). I don't use Inventor at work but was already familiar with the standard AutoCAD software so it did not take long to teach myself Inventor and is it relatively intuitive

Craig

good thing my lathe has a replicator button... going to be needing that a lot on this build