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How to ruin a perfectly good stock frame

  • Thread starter Thread starter mlc216
  • Start date Start date
I'm just commenting on the trend that anything done that isn't OEM is usually poo-poo'ed on this forum.

My beef with so called "customs" is the fact that the huge majority of them wind up with straight pipes, or something similar. Why?
 
Shear strength is one thing, but there are other important design considerations for a motorcycle frame too, such as torsional and lateral rigidity of the front end so the frame is not unstable at speed when upset by road inputs. I suggest you run some moment of inertia calculations on the torsional and lateral stiffness of your design, particularly the front end, and compare to a stock 450 frame as a reference. This frame is clearly designed to flex in a vertical plane, which may be okay for a ridged frame, but a torsionally flexy front end with make the bike prone to possible tank slappers.

With more rake comes more stability at speed as long as the rake/trail calculations are correct. I'll check into the torsional and lateral stiffness as well, but as I said before the bike will not, and was never meant to handle like a sport bike. It will handle much more like a cruiser with most of the weight residing over the back wheel which removes a lot of force from the front end especially in cornering. Yes, this removes a certain amount of traction from the front end, but again it's not a sportbike.
 
keep up the good work mlc216 and keep them pics coming in.
ignore the boring farts that are only interested in concourse restoration projects, they have no imagination
 
Ha well I don't want anymore drama. I appreciate the concern, but let me finish it up and we can discuss what areas may need more support then.
 
Hey what's the matter with straight pipes!?! My 550 has them, well with an internal restrictor. It's disappointingly quiet! Guess the small cc's have a lot to do with that.
 
My beef with so called "customs" is the fact that the huge majority of them wind up with straight pipes, or something similar. Why?


What's wrong with straight pipes? My bike sounded **** with straight pipes...I just didn't want the volume.
 
I heard a larger capacity GS go past me once that had no baffle or muffler, I thought it sounded like it was farting...

I'm not noise police, but I think inline fours and parallel twins actually sound better with at least some restriction.

V Twins sound good with less, but I find the Harley's with the crowbar modification offensive, and most Harley riders around here seem to do that.

I'm pretty sure our GS' are designed for some back pressure too...

That's just my 2c on open pipes...

MLC, keep going, I wanna see this new one :D
 
Here's a question, you say you are an engineer, let's see the math. Looks like a death trap to me. This from one who has had a serious crash from a frame failure, the whole steering head popped off the front of my first bicycle. That bicycle frame was more stout than this one.

My fathers first motorcycle, an early 2 stroke Harley did that to him...
 
I heard a larger capacity GS go past me once that had no baffle or muffler, I thought it sounded like it was farting...

I'm not noise police, but I think inline fours and parallel twins actually sound better with at least some restriction.

V Twins sound good with less, but I find the Harley's with the crowbar modification offensive, and most Harley riders around here seem to do that.

I'm pretty sure our GS' are designed for some back pressure too...

That's just my 2c on open pipes...

MLC, keep going, I wanna see this new one :D

The pipes on my gs have homemade baffles. Idled like crap and had no low end power at all with the straight pipes the previous owner fab'd up... I believe in back pressure
 
Look in my sig to see how mine sounded with open pipes :D

You can also hear it with the shorties :D
 
Springer is a little too long so I'll be saving it for something else down the road. Had to cut the grass tonight so all I did was bolt on a little more accurate mock up...
9e07c4b1.jpg
 
Now that's better. :)

I still think it's a good idea to put some bracing from under the tank somewhere towards the lower end of that triangle-brace at the headstock. ;)
 
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