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

Frame Maker

Well-known member
I don't know how I missed this thread, but I'm glad I found it.

I'm excited to see the progress Julian!

What the hell Josh? Well, I'm glad you found this thread... and your name should be at the top of the list for potential track test riders:ride

PS- what's your preferred seat height on those yellow bikes you ride?
 

Frame Maker

Well-known member
This past week's progress:

With the 3D prints now in hand, it's time to build a mock-up of the mid-frame and see how it fits to an RZ350 engine. In the shop I turn the cross tubes for the mid-frame. Some scraping with a utility knife is needed to smooth and remove a small amount of material from the 3D prints to get the aluminum cross tubes to a nice press fit. The 1/4" plate engine mounts and lower suspension mounts have already been laser cut a few weeks ago.

20210206_161119 by andbike, on Flickr


My aluminum welding skills are virtually non-existent, but I manage to tack weld the plates to the tubes and assemble the mock-up.

20210207_113335 by andbike, on Flickr

20210207_113403 by andbike, on Flickr


With the mid-frame mock-up completed, time to see how it fits... Oh Shit! It kinda doesn't fit. Well, this is exactly why I made the 3D prints before spending real money on CNC machined aluminum parts. So I'm glad to catch this interference early.

There is an area where the 3D printed side plate is interfering with the clutch cover. Using my Dremel with a small saw, I trim away some material and now the mid-frame will fit, although I don't like how the clutch cover is now captured under the plate and can't be removed with the engine in place.

20210207_142245 by andbike, on Flickr

20210207_150045 by andbike, on Flickr

I'll readdress this issue later and possibly make some design changes to the side plate. On the left side there is an interference with the left side engine cover. If I use the original RZ350 side cover the interference is significant, although the left side covers are plastic and can be trimmed. The interference is only in the area that covers the c/s sprocket so nothing structural or containing fluids would be compromised. If I swap to a Banshee left side cover the interference is very minimal. The RZ side covers are getting scarce while the Banshee covers are still available from Yamaha. So that will be the solution.

Also this past week more laser cut brackets arrived so I can finalize the seat mounts. I love how they blister pack everything so nothing falls out of the packaging. I've used laser cutting vendors in the past who possibly never had customers from remote locations and their packaging was horrible. Anyway, the flat brackets are easily formed to final shape.

20210207_134904 by andbike, on Flickr


One bracket is for the center tongue on the seat. The other brackets are for the rear screw mounts. The rear brackets are intentionally long and require some sanding to remove material for final fit.

20210208_121011 by andbike, on Flickr

20210208_132508 by andbike, on Flickr



Then a few tack welds to confirm fit, followed by final welding and the seat is ready to be mounted.

20210208_141213 by andbike, on Flickr

20210208_143347 by andbike, on Flickr


When I first started building frames I would use rivet-nuts any place where I couldn't access the back side to place a normal nut. Now I like to use these clip-nuts. They work very well and if they ever get stripped or damaged just throw away and use another one. Super handy.

20210208_160246 by andbike, on Flickr


I have a fiberglass tail for a KTM cup bike that I like the shape, however it doesn't fit to the R6 seat very well. For now I'll use a Yamaha replica tail just to see how the bike will look with a race tail. At first I try one based on 99-02 R6 to see how it looks.

It looks much better than the utility rack I had used for the Dirtbag ride, but it still looks kinda clunky.

20210209_114305 by andbike, on Flickr

20210209_114644 by andbike, on Flickr

Next I try a replica tail for a 03-05 R6. Its a little lower and seams to follow the styling of the tank much better. This is an improvement and I'm finally starting to get aroused by how the bike is looking:party

20210209_145410 by andbike, on Flickr

The long term goal is to sculpt a tail that fits properly to the R6 seat, but has the rear portion based on the KTM cup bike tail. But that effort will wait. For now the priority is getting the frame re-design finalized.


More to come...
 

kpke

Veteran
This is looking excellent. Really quite unbelievable to start with metal tubes (and other things), get bits and pieces ordered and fabricated from all over the world, and end up looking like this. Thanks for the update. :thumbup

If I may ask, why a wizard fabricator welder dude like you has difficulty with welding aluminum?
 

auntiebling

megalomaniacal troglodyte
Staff member
That laser vendor has been pooping up on my facebook feed... I just dont need to laser cut stuff I want to try!
 

bikewanker

Well-known member
Even with more coffee it’s mostly beyond my comprehension how you’re fabricating a frame Julian! Have enjoyed following this process. For me it’s kinda like a Playboy magazine, I gots to have pictures to understand.
Thank you.:thumbup
 

bobl

Well-known member
Looking great! I like the 03-06 r6 tail the best. Do you have any idea of what the final weight well be? Will it be a track only bike or road registered? Amazing work!
 

Frame Maker

Well-known member
...If I may ask, why a wizard fabricator welder dude like you has difficulty with welding aluminum?

Welding steel and welding aluminum are different in how the material reacts to heat. When I first learned to weld I did a lot of body repair on old VWs. Everything was always steel. I got confident with steel. Then when I started to build motorcycles I wanted the aluminum parts to be perfect and was introduced to Dennis Etcheverry at Norman Racing. His aluminum welding is some of the best I've ever seen. I don't need aluminum welded very often so I just keep going back to Dennis whenever I have aluminum parts to weld.

20170815_125630 by andbike, on Flickr


That laser vendor has been pooping up on my facebook feed... I just dont need to laser cut stuff I want to try!

Their minimum order amount is only $29 (for most materials) and includes 2-day shipping to the bay area. So its pretty cheap even if you just want to experiment. They've recently added carbon fiber sheet, so maybe heel guards or some simple accessory for a moto project would be easy if you want to try it out.

Even with more coffee it’s mostly beyond my comprehension how you’re fabricating a frame Julian! Have enjoyed following this process. For me it’s kinda like a Playboy magazine, I gots to have pictures to understand.
Thank you.:thumbup

Ha! I like your Playboy pictures analogy! :thumbup Thanks!
 

Frame Maker

Well-known member
Looking great! I like the 03-06 r6 tail the best. Do you have any idea of what the final weight well be? Will it be a track only bike or road registered? Amazing work!

Thanks:thumbup

Yep, the general consensus is the 03-06 tail, so that will stay on... for now.

Using a bathroom scale I have the wet weight (tank partially full) at about 285 lbs with approximate 54/46 distribution front to rear. With the utility rack gone, it is likely a little less right now.

The bike is titled and street legal. I've already ridden about 600 miles on it. Since I'm reconstructing the rear sub-frame the tail light and license plate are off right now. A few pages back in the thread I discuss the DMV / CHP / inspection process. I also hope to do some track testing. :ride

20201013_130305 by andbike, on Flickr
 
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auntiebling

megalomaniacal troglodyte
Staff member
Their minimum order amount is only $29 (for most materials) and includes 2-day shipping to the bay area. So its pretty cheap even if you just want to experiment. They've recently added carbon fiber sheet, so maybe heel guards or some simple accessory for a moto project would be easy if you want to try it out.
!

that's good to know, thanks!
 
What the hell Josh? Well, I'm glad you found this thread... and your name should be at the top of the list for potential track test riders:ride

PS- what's your preferred seat height on those yellow bikes you ride?

Ooh, yes I'd love to test it out!

I've been playing around with seat height. I'll measure it this weekend and get back to you.
 

Frame Maker

Well-known member
I just finalized the last CAD revisions to the CNC machined parts. I fixed the engine interference and moved the engine 3mm forward just to give a bit extra clearance. Then sent off an RFQ to my secret Chinese vendor. Fingers crossed.
 
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