The Process Continues

So last week I wrote how I’m modeling this motorcycle in Solidworks to build up my portfolio. I figured for this week I’d give a short update.

So the engine I chose is a Ducati 900cc L twin. The model I sourced did not have the carburetors. Carburetors are the part of the engine that are responsible for mixing air and fuel together, which then goes into the engine to be ignited. The carburetor (carb) is the part that the throttle cable connects to; as you twist the throttle, a plate on the carb twists open, and more air is allowed to enter the engine. More air+fuel = more power, and that’s what makes the bike go vroom. Thankfully carburetors aren’t necessarily engine specific, so I managed to source these.

This is an S&S Super carburetor. It’s a popular choice among the Harley community. My engine has two cylinders, so there needs to be one carburetor per cylinder. Space is tight, so I played around with it and oriented the carburetors so that

  1. Both carbs could be operated using a single throttle cable without a complex linkage system
  2. Pipe connections between the intake port on the engine and the flange on the carb would be easy to fabricate

After about an hour of playing around with it, I settled on this configuration.

Right now they’re floating in space, but a pipe will connect the back end of the carburetor to the big hole in the side of the engine cylinder that you see.

It was at this point I realized I had an issue: the diameter of pipe the air flows through in the carb is 1.875”. The diameter of the hole of the intake port on the engine is only 1.5”. This means air will be restricted entering the engine. One workaround is to make an intake pipe that is 1.5”. If I did that, air would enter a 1.5” hole, open up to a 1.875” hole, then go back down to a 1.5” hole. Since it’s entering and exiting at 1.5”, it shouldn’t cause as much of a disruption as it would if it were entering at 1.875” and trying to fit into a 1.5” hole. Maybe I’ll do one of my project problems on that so I know before hand.

Anyway, that’s my update for the week. Once I figure out what’s going where on the engine, then I’ll know what my space limitations are and I can start on the frame design. Thanks for reading!

PS. Shameless plug time. Check out my portfolio insta @3dkevin