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

C'mon Julian. It's almost 5:30 AM and I'm anxiously waiting for the Monday update.:thumbup
 
kpke said:
C'mon Julian. It's almost 5:30 AM and I'm anxiously waiting for the Monday update.:thumbup
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Lonster said:
:laughing
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Dang, the fan club is getting impatient these days.:wtf I'll take a look in my phone and maybe see if I have a picture or two that I can post during my lunch break today.:party

Wait, wait, wait... a certain fan boy is only five minutes away and COULD HAVE simply stopped by to see if anything was going on in the driveway.:x
 
While we're waiting for the Monday update, I leave this mystery to solve....

While gathering parts to assemble a rolling chassis (pictures at noon :twofinger) I came across this random shock in my garage. I have no idea where I got it or what bike it fits. In the back of my mind I kept thinking it was an old Sachs from a Ducati project. But on closer inspection its a genuine Ohlins with an Ohlins spring. Based on the picture any ideas what it might fit:dunno

20210815_212335 by andbike, on Flickr
 
This weekend's activities began Thursday with some parts scrounging so that one of the gen2 frames could be made into a rolling chassis. Complete GSXR600 frontend (which has now passed between several BARF faithfuls), TZR250 3XV swingarm, R6 shock, and SV650 rear wheel. These aren't the final parts, but will work for getting the frame temporarily on wheels.

Now its starting to look like something!

20210814_142330 by andbike, on Flickr

20210814_142344 by andbike, on Flickr

side by side with gen 1 for reference...

20210814_142729 by andbike, on Flickr

This weekend's activities are to build sub-frames. Unfortunately the process went much slower than originally anticipated and I only finished half of a sub-frame. The first one is always built directly on the bike in a figure-it-out-as-I-go method. Not sure why I though I could build three:dunno

Anyway, Saturday started with machining two simple parts. Well, actually 8 of each, so that took some time. The first bits are the lower sub-frame mounting lugs...

20210814_135055 by andbike, on Flickr

Next up was the front tank mounting lugs...

20210814_171120 by andbike, on Flickr

These allow the front of the tank to mounted to the frame and everything going rearward follows and dictates construction of the sub-frame.

20210814_173239 by andbike, on Flickr

I would spend many hours on Saturday standing in front of my lathe, but finally with all of the lugs done I was able to begin on the sub-frame structure...

20210814_192641 by andbike, on Flickr

Back in the shop on Sunday, the plan is to finish the first sub-frame. Here are the lower lugs in place and some marks where the upper mounts will be placed.

20210815_125303 by andbike, on Flickr

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Next is making a cross brace that will support the front of the R6 seat. It will get plenty of holes to reduce some weight.

20210815_134650 by andbike, on Flickr

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With the seat able to be loosely put in place I'm able to determine the seat angle that I like and begin the process of making the diagonal support tubes. The first one is always a bit of trial and error. Once it fits well I'll make a paper pattern and using the pattern make the opposite side.

20210815_152239 by andbike, on Flickr

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20210815_162651 by andbike, on Flickr

Next, a length of square tube is cut length wise to make a C channel that is then beveled and welded into an inverted U shape. The ends are notched and 6mm holes drilled in each side. This is the rear tank mount.

20210815_171755 by andbike, on Flickr

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The last bit that I would have time to complete on Sunday is this little bit of sheet metal origami that will become the seat tongue mount.

20210815_190746 by andbike, on Flickr

I happen to have an extra from when I built the Gen 1 frame, but the length is way off. I already have it bent to shape and need to notch it with a hole saw. How do I hold such an awkward part? The solution is to weld it to a square tube that I can hold in vise. The weld is placed where the material will be cut away and thus release the finished part. It works!

20210815_185852 by andbike, on Flickr

This would be as far as I get on Sunday. Sub-frame started. Tank mounted. Seat partially mounted...

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Okay, now did anyone figure out what the Ohlins shock is off of?
 
Beautiful work Julian! Your work is really unbelievable to mere mortals (garage hacks) like me. :hail

That roller is really looking awesome. It's a great to see it coming together.

Thanks for sharing the build details. :thumbup:thumbup:thumbup:thumbup:thumbup
 
This would be as far as I get on Sunday. Sub-frame started. Tank mounted. Seat partially mounted...
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“As far as I get”! I might get in 2 oil changes on a weekend.
Beautiscious work Julian! Thank you
 
kpke said:
Beautiful work Julian! Your work is really unbelievable to mere mortals (garage hacks) like me. :hail

That roller is really looking awesome. It's a great to see it coming together.

Thanks for sharing the build details. :thumbup:thumbup:thumbup:thumbup:thumbup
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Joshman said:
Wow, that thing is really coming together!
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bikewanker said:
“As far as I get”! I might get in 2 oil changes on a weekend.
Beautiscious work Julian! Thank you
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Thanks guys! I appreciate everyone's encouragement. I've been at it pretty hard for the past few weekends trying to get a completed frame to a race team planning to be at the AHRMA event at Barber in October... but we had a discussion yesterday and mutually decided not to kill our selves getting a bike built by then. Still plenty of big events early next year. So I may back off this pace and save my sanity.
 
If I had to give a title to this weekend update, it would be "Its All About the Seat!" When we left off last week I had begun the rear sub-frame and got as far as adding the front seat support. I only had half a day available on Saturday, so my focus was on completing the mounts and support for the seat. The rear mount consists of a cross support and two tabs.

The cross support starts as a 1" x 1" square tube that is split lengthwise then holes cut for lightening. I went ahead and made three cross supports since I had the mill set up for this operation. Whats not shown is a bunch of careful sanding that happens after the tube is cut lengthwise to get the edges nice and straight where the cut was made.

20210821_155030 by andbike, on Flickr

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The very small holes are vent holes since there will be small upright tubes that connect the cross tube to the sub-frame, and those need to be vented if they get welded all the way around.

Next, is adding the tabs that the seat will attach to. I happen to have a few extras laser cut when I built the revised sub-frame on the original prototype bike.

20210821_171633 by andbike, on Flickr

Here's a good picture of the short little upright tubes.

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It doesn't seam like a lot of work, but it took a good solid half day to get this bracket fabricated and mounted in the correct position.

20210821_183009 by andbike, on Flickr

And now the seat can be bolted in place.

20210821_183555 by andbike, on Flickr
 
Sunday morning I took a good look at the profile in the morning and decided I wasn't happy with the seat angle. It was just slightly too high in the back. It reminded be a bit of the streetfighter crazy that hit the UK a few years back where everyone jacked up the tails really high. It wasn't that bad, but I decided it needed to come down just a bit.

20210822_104240 by andbike, on Flickr

Here are a few more angles. Note, the tail is barely in place for the photos.

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Back at the shop, I've cut off the rear support and re-made the stubby little support tubes. This time they're about 1/4" shorter.

20210822_124903 by andbike, on Flickr

And back on with the cross support.

20210822_133915 by andbike, on Flickr

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I would spend the remainder of Sunday, starting on the rear sub-frame fixture. This is a process of building a structure that will pick-up all of the mounting points from the sub-frame so it can be easily duplicated later. Its a bunch of rough cut tubing and tabs. Along the way I check for symmetry. The most important aspect of building the fixture is to be sure the original sub-frame and subsequent sub-frames can be removed from the fixture. So some though goes into how everything is positioned. Oh, and I also need to keep in mind welding access. So just a few things to think about along the way.

This is an odd little set up, but it worked really well for drilling two 90 degree tabs with holes at equal height.

20210822_142648 by andbike, on Flickr

Now it just adding tubes and tabs...

20210822_155130 by andbike, on Flickr

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Its not finished, but go most of the front portion completed.

20210822_183241 by andbike, on Flickr

20210822_183646 by andbike, on Flickr

Back home at the end of the day I mock-up the seat and tail. It probably doesn't look any different in the photo, but I like the slightly decreased angle much better! It was a good call to make the change. I'm very happy with how its looking.

20210822_193913 by andbike, on Flickr

Stay tuned for a possible mid-week trivia question:party
 
I should probably mention that I'm measuring the seat height at just a bit over 32" (Maybe 32-1/2") measured at the center of the seat. This is with suspension topped out, so should come down a bit with normal sag once the bike is completed. So this seams like a good height based on the feedback here:https://www.bayarearidersforum.com/forums/showthread.php?t=548278&highlight=seat+height+survey

As an interesting side note, for the sake of conversation I typically measure seat height around the mid-point back along the slope of the seat. I just asked a co-worker who has worked at both EBR and Zero and his experience with those companies they would typically measure seat height at the lowest point at the front where the seat mates to the tank / cowl. So there is that. So my measurements might not be consistent with industry standards. Oh well. It feels good to me:thumbup
 
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