Homemade motorcyle build

Hey Mitch, I think it's really great that you're applying your education like this. You will be way ahead of many of the others when it's time to market your skills.

That being said, I have to agree with Ian. A carriage, be it a plane or a bike is easier to fit around a drive train than the other way around.

Good luck.
Rusty

Hi Mitch
I was born into a family that revolved around motorcycles, from father to three sons of which I am the youngest. We have all at some stage ridden, built, raced, destroyed engines or bikes (I file these under learning curves) and my own son raced Junior speedway for a while. I agree wholeheartedly with Ian and Rusty in concentrating on the power plant first. Your chassis design will depend basically on three main things, your engines weight, design and power output so you will need some idea of these first. If you intend building a multi cylinder engine like you have pictured, i.e. flat six, it’s a good idea to build a flat twin BMW style (or single) first for testing and add the other cylinders later. Bear in mind that engines of this configuration stick out the side and thought has to be given to ground clearance when cornering. Raising the engine helps somewhat but this raises the centre of gravity which affects handling. While you are building your engine there are some very good books on chassis design you can read along the way. Check out the second hand bookshops and ebay or the library if you have one close by. Once you have your engine ready for road testing go in to a motorcycle wrecker. You should be able to find a complete rolling chassis, minus engine, suitable for yours. Much cheaper option than building your own at this stage. This test bed plus what you read and learn along the way fuelled by your imagination will guide you in building your own. You will encounter seemingly endless hurdles, every problem solved leads to another problem but that is the whole point of the exercise and when you wheel it out of the workshop, start it and head off on your first test ride the pleasure is indescribable I commend you and wish you well. Dave

With flat opposed, maybe take a note from BMW and go shaft drive...your call all the way though.  Seems like it will be kinda LONG for transverse mounting.  I am not gaining appreciation for the actual size of this engine.  

48x6 = 288cc
66*6 = 396cc

I think it is generally true there is no replacement for displacement, especially when normally aspirated engines are involved (OK, a super/turbo arrangement can replace a lot of displacement).  I also know that a LIGHT 250cc performs well, but a heavy one is a dog.  400CC is a nicer number.  Big enough that weight will be less critical.

Frames are easy, just need to know what fits where and make it all line up.  If you don't know what fits where then maybe it would be better to build from the inside out.  I don't know how detailed your drawings are, so you might be OK starting with the frame if the entire machine is fully drawn and modeled.

Lastly, I do not ride.  I wanted to get my endorsement but did not have the money when a bike was available to learn on.  (This was my Mom's Kawasaki, Dad had a Triumph when I was growing up, both have been sold since)  A couple years ago I rode my Dad's new 250cc "scooter" which was almost enough to hook me solid on motorcycles.

Phil