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

Oh and I'll share something on a more BARF related too, for those interested and who haven't traveled much to Asia, even the motorcycle culture is pretty different. In the states I always felt bikes are more sought out by people who are interested, and that mainly the US has a car culture and a minority who like motorcycles. Then in Taiwan almost everyone rides a scooter or motorcycle. I remember being a new unconfident rider, then going to Taiwan and seeing 60, 70 year old men and women riding motorcycles and that for sure gave me some confidence haha. It's just a fact of life over there that more people will need bikes, cause who can afford cars? Streets are tiny too, but they're expensive as hell over there.

Here's a cool little note, so check out this video at the 24 second mark. Sooo this is how scooters turn left in Taiwan, they have a little left turn box. So instead of sweeping through an intersection to go left, you go straight first, go into the box, then wait for the next green. How cool is that?!?! I did hear they might be removing some of these because of accidents, but always thought that was neat. Oh Taiwan how I miss it now.
 
Awesome to hear your stories though so thank you for sharing!

Its been fun sharing stories. Thanks for listening to them!

...I remember being a new unconfident rider, then going to Taiwan and seeing 60, 70 year old men and women riding motorcycles and that for sure gave me some confidence haha. It's just a fact of life over there that more people will need bikes, cause who can afford cars? Streets are tiny too, but they're expensive as hell over there.

Here's a cool little note, so check out this video at the 24 second mark. Sooo this is how scooters turn left in Taiwan, they have a little left turn box. So instead of sweeping through an intersection to go left, you go straight first, go into the box, then wait for the next green. How cool is that?!?! I did hear they might be removing some of these because of accidents, but always thought that was neat. Oh Taiwan how I miss it now.

Meanwhile deep in mainland China left hand turns are done like this...

DSCN9474 by andbike, on Flickr

Yes, that's a bus followed by a car that went down the wrong side of the road so that they could use the oncoming right-turn pocket to make their left turn! Fucking insane, but everyone (or at least 30%) drove like that:wtf For perspective, I took the picture from the back seat of a car waiting in the left turn lane to make a normal left turn.

One thing I did notice that was different on the mainland than in Taiwan was the lack of regular motorcycles. Scooter by the millions, but I almost never saw what we consider normal motorcycles on the mainland. A friend of mine said that motorcycles are thought to be very dangerous (compared to scooters) and have been outlawed in big cities.

Okay, last story to add a bit more moto content... One Sunday I was invited to go hiking with my co-worker Alex and two engineers from the injection molding factory I was working with. We went up into some hills near Suzhou. It was unbelievably crowded. Some of the trails were so steep you had to climb using ropes that had been put in place, yet there were old women in skirts and sandals climbing along with everyone else.

Anyway, we get to the top of ridge and I could hear dirt bikes in the distance. This was VERY odd considering I rarely saw any motorcycle of any kind (expect the occasional police moto). So we hiked down toward where we had heard them and came upon three riders with modern trials bikes. It was strange see them, and even crazier was the fact that the trails were super crowded with pedestrians, yet these guys and one gal would blast up the trials between all the people who would have to jump out the way. Only in China!

20190324_140759 by andbike, on Flickr

20190324_135855 by andbike, on Flickr

20190324_140708 by andbike, on Flickr

20190324_135144 by andbike, on Flickr

I did stop and chat (using Alex as my translator) with the guy in the neon jersey. He was very friendly, especially when I showed pictures of some of my own motorcycle projects. He even offered to let me try his trials bike. Given the crowded conditions, not having my own helmet, and general being exhausted from the long hike I decided best to decline... although very cool that he offered:ride:thumbup
 
Okay, now back to our regularly scheduled program... expecting a big update on Monday! Stay tuned:party
 
Okay, coming a few hours early... your Monday update!

To start off, I received the 4mm taller front engine mount brackets and they were spot on:thumbup This allowed for some significant progress to happen on Saturday:

20210731_102939 by andbike, on Flickr

Clamped and ready to tack weld in place:

20210731_113104 by andbike, on Flickr

Then the other side. Yes, the entire frame fixture can rotate 360 degrees:

20210731_115120 by andbike, on Flickr

Next up is to fit the short vertical tubes:

20210731_125844 by andbike, on Flickr

Don't forget to vent any place where the welding will completely close off a tube creating a potential blow out. The vent hole allows heated air to escape as it expands from the welding heat.

20210731_142941 by andbike, on Flickr

Engine mount brackets, head tubes, and vertical tubes all tack welded in place:

20210731_150301 by andbike, on Flickr

Now on to prepping the upper shock mount hoop:

20210731_164303 by andbike, on Flickr

Even though everything is only being tack welded at this point, the shock mount hoop overlaps an weld between the main frame tubes and the joint lugs, so I decide to pull the frame out of the fixture and complete the portion of the weld that will be covered:

20210731_165841 by andbike, on Flickr


And another vent hole:

20210731_171311 by andbike, on Flickr

Wow! the hoop fit perfect the first time. No back and forth to sneak up on the exact fit. Just notched it once and fitment is good!

20210731_174201 by andbike, on Flickr

20210731_174223 by andbike, on Flickr

After all the prep work, the gen 2 frames are underway!

20210731_180452 by andbike, on Flickr

20210731_180505 by andbike, on Flickr

20210731_180528 by andbike, on Flickr

At this point I call it a day and head home to do some check fitting
 
Back home I get out one of the mid-frames and a pair of front engine mounts and begin the test fit process. I'm worried that the mid-frames will be difficult to fit to the front frames, but the fit is perfect! Holy shit. How did that happen?

20210731_224258 by andbike, on Flickr

This is starting to look really nice. Its been a long process getting to this point, but worth the effort and wait!

20210731_224512 by andbike, on Flickr

I love the fitment between the trellis and the CNC mid-frame. I'm really happy with the details.

20210731_224638 by andbike, on Flickr

The 4mm wider engine mount brackets make for more of a gap between the front engine mounts and the main frame tubes, so that I'm not as happy with. Oh well. Can't be perfect I guess.

20210731_224647 by andbike, on Flickr

Few more views of the back:

20210731_224657 by andbike, on Flickr

20210731_224730 by andbike, on Flickr

Okay, now for the moment of truth. Don't tell my wife, but I dragged in a filthy old RZ350 engine and propped it up on the kitchen table. Now very carefully try to get the engine and frame to line up. The first problem is the rear engine mount tabs are a bit tight. This takes some persuasion with large screw drivers then eventually a few taps with a dead blow to bend the tabs apart just slightly as to fit the rear engine mount. Okay, with the rear mounted I carefully lower the front of the frame over the front engine mounts. Oh wait. Something doesn't look right... fuck! the engine mounts are off by about 6 or 7 milimeters. Crap!

I'm able to stress the rubber engine mounts and get the front bolt in but something isn't right. With the engine finally in, I do an inspection and all of the previous problems with the gen 1 frames are gone. So that is good. There is plenty of clearance between the rear of the engine cases and the swingam pivot area. The power valve housing has a few milimeters of clearance. So several problems have been solved, but still scratching my head about the engine mount spacing.

20210731_231718 by andbike, on Flickr

20210731_231838 by andbike, on Flickr

20210731_231909 by andbike, on Flickr

20210731_232131 by andbike, on Flickr

Its now very late Saturday night. So time to get some sleep and let the brain re-fresh. I'll try to figure out the engine mount spacing on Sunday.
 
Saturday night while still awake I go back and forth about solutions for the engine mount spacing. I'm pretty sure the problem is because in the design process I re-positioned the engine several times moving it a few millimeters each time to ensure it wouldn't be up against the swingarm pivots. When I sent out drawing files to laser cut the rear engine mount plates, I likely used and older version. I did notice they fit kinda odd in the welding fixture, but I made a quick adjustment and never really thought about it again.

Okay, that's how the problem came to be, but what's the solution? Its too late to re-make the mid-frames so that's not going to happen. I could try to slot the rear engine mount brackets, but not crazy about that idea. I could make the holes in the bracket for the front engine mount plates oversize so the front engine mount plates can float a bit. Not really crazy about that either.

I decide to do another mock-assembly using bare RZ cases since I know the other engine clearance issues are solved. Just for giggles I decide to completely unbolt the front engine mount plates form the frame and see where they naturally want to fit with the engine cases mounted. Well this is interesting. Moving the front engine mount plates closer, but still parallel to the frame tubes and everything fits pretty well... and that gap that I didn't like is gone! Okay, that's a win.

20210801_141354 by andbike, on Flickr

Back at the shop I attempt to modify my remaining engine mount brackets. I stack them together and add some weld beads that can later be ground off. This way I can modify the brackets together. Unfortunately the new holes overlap the existing holes so they can't be drilled. I try using an end mill, but it chatters really bad (the bit is probably dull?). Anyway, I decide to stop and will just change the profile in CAD and order another batch of brackets.

20210801_141407 by andbike, on Flickr

I spend the remainder of Sunday afternoon notching three more rear shock mount hoops and grinding the remaining frame lugs. I'm not sure if it was mentioned earlier, but there is 2 degree miss-match between the main frame tubes and the lugs. This was intentional. A straight design makes it much easier to make the lugs and its only a few minutes of work to grind the the slip fit enough so that it will rock a few degrees. Anyway, it was not what I planned to do Sunday, but still a good use of time. I hope to have the (again) revised brackets by next weekend.

Here are a few last photos of the progress. In the detailed photo you can really see the asymmetry in the lower frame. Left side is low for chain clearance. Right side is high for expansion chamber clearance.

20210801_185153 by andbike, on Flickr

20210801_185554 by andbike, on Flickr

New CAD files have been sent for laser cutting. Fingers crossed that this is the last time that those change.

Stay tuned. Still more coming next week :thumbup
 
Didn't you have any new RZ350 engines handy?

Ha ha... thats funny! Seriously though, if all goes as planned I'm hoping to get a mostly new engine with some fancy aftermarket cylinders in trade once a few frames are completed. Maybe then I'll have a (mostly) new RZ350 engine:party
 
Excellent progress and amazing pictures. Thanks again for keeping us updated. I hope this is as much fun for you as it is for us. I'm sure you've already thought of this, but did the 4 mm adjustment you made on the tabs affect where the front engine mount holes end up?
 
Excellent progress and amazing pictures. Thanks again for keeping us updated. I hope this is as much fun for you as it is for us. I'm sure you've already thought of this, but did the 4 mm adjustment you made on the tabs affect where the front engine mount holes end up?

Really good question, but the position of the holes for engine mount bracket is located by the main fixture. The extra 4mm was added to the edge that interfaces to the main lower frame tubes (which were not matching the location in CAD). So the front engine mounts haven't changed location. It was definitely the rear engine mounts where the mistake happened. But front engine mounts will be moved to create the fix. This fix will tilt the front of the engine up a few degrees, but that is the compromise to keep things moving forward. If I ever make more frames beyond the first five, then I'll re-address the issue with a correct solution. For now, I'm happy that this has been the only significant issue... knock on wood!
 
hxABcTq.jpg


Mr. Wizard,

That's quite an update. Sucks on the alignment issues. :(

It's really starting to look like something very, very special. That's a lot of extremely brilliant work.

I am curious, do those beautiful aluminum parts get finished, i.e., anodize, hard anodize, or something?
 
hxABcTq.jpg


Mr. Wizard,

That's quite an update. Sucks on the alignment issues. :(

It's really starting to look like something very, very special. That's a lot of extremely brilliant work.

I am curious, do those beautiful aluminum parts get finished, i.e., anodize, hard anodize, or something?

Did you say "brilliant"... you had better watch what you say around here as someone might take offense to that type of language:twofinger

There is no reason why the aluminum bits couldn't be anodized, but I like to keep them raw as it makes them easier to polish from time to time... if I just knew what happened to my polishing machine :laughing
 
Who's ready for a Monday update?

Last weekend when the engine mount spacing was found to be off, I drew up a revised design for the front engine mount brackets and got files off to SendCutSend for laser cutting. The new brackets arrived on my front porch by Thursday. I love those guys!

Okay, so back in the shop on Saturday and first thing on the agenda was to test fit the changes with the engine mounts. I quickly got the tack welds ground off and brackets removed, then frame back in the fixture.

20210807_111756 by andbike, on Flickr

New brackets fit up nice, so those get tack welded in place...

20210807_113439 by andbike, on Flickr

Then back out of the frame fixture for a final fit check. All looks good and engine fits! I also like having the front engine mounts up close to the lower frame tubes. Win Win!

20210807_120801 by andbike, on Flickr

20210807_122032 by andbike, on Flickr

Then this happened! Just like rabbits...

20210807_194719 by andbike, on Flickr

20210807_194817 by andbike, on Flickr

20210807_195128 by andbike, on Flickr

20210807_194941 by andbike, on Flickr
 
Just like rabbits.:laughing
Precise and repeatable is a good thing.
 
Well crap, now I just tripled the amount of work remaining to get these frame(s) finished!

Back in the shop on Sunday its time to add front cross tubes and diagonals. These will significantly strengthen the area behind the steering head where the highest loads are likely to occur.

First is the cross tubes. This is fairly straight forward. cut a length of tube. Notch each end, and install.

Here's the notching process...

20210808_114247 by andbike, on Flickr

20210808_125352 by andbike, on Flickr

And tack weld into place...

20210808_142023 by andbike, on Flickr

Oh wait! Where did this frame come from? For those who have been following from the beginning will remember that I started building two prototype frames, but only finished one. So I decided to make some progress on the second prototype frame while I was making cross tubes and diagonals. So here the cross tube has been added...

20210808_142201 by andbike, on Flickr

The diagonal tubes are much more work to trim and fit. Because they are at a steep angle and at one end fitting to a curved area of the main frame, they are not a simple process to notch and fit. Here's the basic process for those...

1. spend a bunch of time hand fitting with lots of trial and error till a diagonal is cut, trimmed, and fits well.

2. wrap a piece of paper around the sample tube and crease the edges. Dirty fingers actually help bring the crease some visibility.

3. use the paper template to transfer the pattern to new sections of tube.

4. cut and trim to the marked lines.

5. lots of careful hand fitting. Done.

I found the paper pattern from the first prototype so I used that to make a set of diagonals for the second prototype frame.

20210808_171123 by andbike, on Flickr

20210808_163730 by andbike, on Flickr

For the gen2 frames the diagonals fit a little different and I am also changing the tube size. Gen1 frames used 1-1/8" diameter tube. For gen2 frames I'm using 1-1/4" tubing. To start I use the original paper pattern, but I adjust the fit to what I think will work with the larger tubing. Even so, I still go through a lot of hand fitting before the first gen2 diagonal fits well. I can then make a new paper pattern and make the remaining diagonal tubes.

20210808_171555 by andbike, on Flickr

20210808_172153 by andbike, on Flickr

20210808_195255_001 by andbike, on Flickr

Sunday was a long day with a lot of hand work so I'm exhausted by the end of the day, but very happy with the progress. The diagnals are ready and will be tacked in place after a bit more welding has been done on the frames. Everything has a proper sequence.

Anyway, it was a good weekend!

20210808_195315 by andbike, on Flickr

20210808_195453 by andbike, on Flickr
 
I love Monday updates !!!

what does the machined aluminum rear engine / swingarm mount gain you that the Gen 1 curved tubing version didn't?
 
I love Monday updates !!!

:thumbup

what does the machined aluminum rear engine / swingarm mount gain you that the Gen 1 curved tubing version didn't?

My original direction was to use an all steel design to keep costs lower. After building the first prototype frame I realized that I created a lot of additional welding. The additional welding also caused a lot of distortion. The aluminum mid-frames made my fabrication much easier, eliminated a bunch of distortion, and most importantly makes the frames look better (who doesn't like CNC aluminum bits):party
 
The aluminum mid-frames are also in keeping some similarity with my AK-1 frames.

DSCN1220 by andbike, on Flickr
 
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