RZ350 re-frame... classic 2-stroke gets modern upgrade

[gixxerjeff]

I'm looking forward to following this build in real time, Julian.

[gixxerjeff]

I'm looking forward to following this thread in real time, Julian.

[bergmen]

This s a great post and thank you for showing us all of the details!

BTW, what 3d CAD program are you using?

Dan

[Frame Maker]

Originally Posted by gixxerjeff

I'm looking forward to following this thread in real time, Julian.

Originally Posted by bergmen

This s a great post and thank you for showing us all of the details!

BTW, what 3d CAD program are you using?

Dan

Thanks Dan.

For CAD I'm using Solidworks. I have a very old seat, but its great for moto stuff.

[bergmen]

Originally Posted by Frame Maker

Thanks Dan.

For CAD I'm using Solidworks. I have a very old seat, but its great for moto stuff.

SolidWorks is the beez neez, good for you! I have just downloaded the latest version but have not had time to get into it. I have some experience with SW 2005 so it has been quite a while. Since that time I've used Creo (used to be Solid Designer) and before that ME30. We have recently transitioned to Siemens NX which is incredibly difficult for me to understand.

Dan

[Frame Maker]

Originally Posted by bergmen

SolidWorks is the beez neez, good for you! I have just downloaded the latest version but have not had time to get into it. I have some experience with SW 2005 so it has been quite a while. Since that time I've used Creo (used to be Solid Designer) and before that ME30. We have recently transitioned to Siemens NX which is incredibly difficult for me to understand.

Dan

I'm a bit envious that you're getting exposure to the top three CAD programs. A few years ago I was a contractor at GoPro. At the time we were working on development of Hero5 camera. There were some new guys that came over from Apple and were NX users. A few engineers were using Creo, and few of us using Solidworks. It was like the wild wild west with anything goes. I was the lucky guy that got to wrangle everyone's sub-assemblies into one master assembly. That was fun trying to import/export between the three CAD programs. It certainly kept me on my toes for sure.

At home I have SW 2006 that I use for the moto projects. There are a few modern features I wish I had access to but (as you can see) I'm doing okay with it as-is.

While we're taking about CAD, I'll put out a shameless plug and mention that I'm currently out of work and looking for employment. My background is in consumer product development with the past 6 years working more specifically on light EVs. It doesn't show in my motorcycle work, but my expertise is in injection molded plastic part design.

Again, nice chatting with you.

[bergmen]

Injection molded plastic is in my wheel house also. My engineering definition is basically the non-analyzer infrastructure engineering design. This is on high end gas phase or liquid phase mass spectrometers and includes everything not in the vacuum system. Structure, card cages, external enclosure, operator interface, serviceability, manufacturability, shock, vibration, all other QA testing, etc. etc.

Creo was easiest and best at this. It is no longer supported so we have to transition to NX (corporate decision).

It is a tough row to hoe but I have to make it work...

Dan

[DefyInertia]

I’m blown away. So rad.

[Frame Maker]

Part 8: real time progress

A few weeks ago my big blue box came home from the hospital. Diagnosis was a bad torch. Although not common, I guess they can go bad after 25+ years of use. While the machine was apart, they also replaced the rectifier bridge, the high frequency points and few other routine maintenance parts. It seams to be working well again. Hopefully good for another 25 years of use.

20210115_133052 by andbike, on Flickr

So on with the sub-frame reconstruction. At the same time I'll be changing the tank and seat to one generation newer. I just like the styling a little better on the '03-'05 R6 tank. The tank mounts are identical to the earlier style tank, but the seat mounting is different. This means that I can't simply copy the original sub-frame.


'03-'05 R6 tank and seat:

20210123_143333 by andbike, on Flickr

To aid in the construction I'll start by building a fixture off of the original sub-frame so that I can easily replicate the frame mounting positions and the tank mount.

Original sub-frame and construction of the fixture:

20210123_143049 by andbike, on Flickr

20210123_143130 by andbike, on Flickr

The fixture is now ready with locating features for the frame mounts and rear tank mount. I can begin building the new sub-frame.

20210129_161421 by andbike, on Flickr

20210130_150049 by andbike, on Flickr

20210130_150058 by andbike, on Flickr



First test fit on the bike looks good!

20210130_162455 by andbike, on Flickr


And very rough mock-up of seat position.

20210130_162839 by andbike, on Flickr


I have a fiberglass tail that I will likely be using. Or I should say that I plan to use a modified version of. The tail looks surprisingly similar to one from a Honda RS125, although when compared side by side the Honda seat is much smaller. This tail is from Airtech and is for a KTM cup bike, although it also looks exactly the same as the tails offered by BeOn with their 450GP chassis kits. Anyway, I like the basic shape. It will need to have the seat area cut open to fit around the R6 seat. At some point I will re-sculpt the overall shape a bit just so it isn't an exact copy, and also to so that is looks more compatible with the R6 tank styling.


Here's a quick mock up with the tail in place. I really like how this is going to look!

20210130_163455 by andbike, on Flickr

20210130_163521 by andbike, on Flickr

Next is to add seat supports and mounting details. Since the '03 seat is different than the '02 seat, this will be back to some trial and error. There will be two supports. One across the front and one across the rear of the seat. Once I'm confident with the position (height) then I add the securing features.

20210201_122101 by andbike, on Flickr

20210201_122117 by andbike, on Flickr

20210201_123106 by andbike, on Flickr


I can now sit on the bike and the seat position feel really good. For some reason all of my sport/road race bikes seam to end up with tall seating positions. When measured at the middle of the seat, the height is about 33". If I really wanted to I could bring the seat down by 1/2". I could also tip the back of the seat down a bit, but it feels really good when sitting on the bike with feet on the pegs. Lowering it at this point would be a significant amount of work for minimal gain... and I'm okay with this position for now.

20210201_122209 by andbike, on Flickr


The seat height is primarily dictated by alignment to the tank and the rear of the tank is located just above the upper shock mount. So without a major re-design of the rear suspension there isn't much room for bring the tank and seat much lower. When I build the second batch of frames (with the above discussed re-design) I'll take another look at the seat height issue. Reviewing spec sheets I see a lot of sport bikes with 30" to 32" seat heights. My AK-1 race bikes have the same seat position at 33" and never had any issues and they have won a lot of races. What do you folks think... is 33" too high for a sport bike?

Stay tuned...

[budman]

Love the tail piece mock up. Sexy.

[budman]

Oh ... for this OG... the higher the seat the better.

[DannoXYZ]

awesome work Julian!

What tubing material are you using?

[bobl]

Originally Posted by budman

Oh ... for this OG... the higher the seat the better.

Amazing work. For this busted up and shrinking old fart, I need lower seats.

[Frame Maker]

Originally Posted by DannoXYZ

awesome work Julian!

Originally Posted by bobl

Amazing work. For this busted up and shrinking old fart, I need lower seats.

Thanks guys. Much appreciated!

Originally Posted by DannoXYZ

What tubing material are you using?

This is a great question, so hoping my answer isn't too engineery...

The short answer is mild steel CREW (cold rolled electric welded) tubing. This is the most common and least expensive type of steel tubing available.

For the long answer, a lot of people have asked me why I don't use higher grade materials such as 4130 (cromoly) or DOM (mild steel "drawn over mandrel") both of which are stronger than mild CREW tubing.

Here is where I usually loose people in the discussion... the first thing to understand is the difference between "strength" (yield strength) and "elasticity" (modulus of elasticity) and why they are different properties, yet still important. The best explanation for each of these properties is to describe them in terms of motorcycles. Elasticity is what we experience when we feel the frame flex. The metal moves a small amount, then moves back to its original location. Strength is what is experienced when a motorcycle is crashed and the frame gets bent. The material has been moved a large distance and doesn't move back. It has "yielded".

So with those two conditions in mind, I will say that both mild steel and 4130 cromoly steel are both nearly identical in terms of their modulas of elasticity. In other words, you would feel the same amount of frame flex riding a motorcycle made from cromoly as you would on a motorcycle made from mild steel. Both materials will flex nearly the same amount under small forces. The difference is when you crash, mild steel will bend (and not bend back) sooner than with the higher grades of steel.

Because of this, I use mild steel. It is cheaper, easier to source, and much easier to fabricate (because of the lower strength). The well known moto author Kevin Cameron once described it something like this... "Cromoly is only an advantage if you can crash hard enough to bend mild steel, but not hard enough to bend cromoly".

Thanks for the question

[GPzPop]

is there a weight advantage to cro-mo over mild steel tubing?

what about your "sourced" cnc parts from overseas ? is there a choice in the alloys used? how is the quality control vs price point ratio?

Originally Posted by Frame Maker

Thanks guys. Much appreciated!




This is a great question, so hoping my answer isn't too engineery...

The short answer is mild steel CREW (cold rolled electric welded) tubing. This is the most common and least expensive type of steel tubing available.

For the long answer, a lot of people have asked me why I don't use higher grade materials such as 4130 (cromoly) or DOM (mild steel "drawn over mandrel") both of which are stronger than mild CREW tubing.

Here is where I usually loose people in the discussion... the first thing to understand is the difference between "strength" (yield strength) and "elasticity" (modulus of elasticity) and why they are different properties, yet still important. The best explanation for each of these properties is to describe them in terms of motorcycles. Elasticity is what we experience when we feel the frame flex. The metal moves a small amount, then moves back to its original location. Strength is what is experienced when a motorcycle is crashed and the frame gets bent. The material has been moved a large distance and doesn't move back. It has "yielded".

So with those two conditions in mind, I will say that both mild steel and 4130 cromoly steel are both nearly identical in terms of their modulas of elasticity. In other words, you would feel the same amount of frame flex riding a motorcycle made from cromoly as you would on a motorcycle made from mild steel. Both materials will flex nearly the same amount under small forces. The difference is when you crash, mild steel will bend (and not bend back) sooner than with the higher grades of steel.

Because of this, I use mild steel. It is cheaper, easier to source, and much easier to fabricate (because of the lower strength). The well known moto author Kevin Cameron once described it something like this... "Cromoly is only an advantage if you can crash hard enough to bend mild steel, but not hard enough to bend cromoly".

Thanks for the question