CB desert sled

+1

So yesterday Alex and I could have worked on the bike, but it was sunny. And that's not the sort of thing we pass up in the middle of November around here.








Looked good, and was even better because I'd never ridden these trails before.

Corey came down this weekend to give Luke a hand. Here they are lapping in the valves on Engine #1, we are still working on Corey's understanding of the word "finesse";


Everyone has an opinion (or two) on how Luke should build his creation;


Here is Loud Al documenting progress;


Saturday afternoon, I asked Luke where he was keeping his tools, after he pointed at this cardboard box the teasing began;

T'was a good weekend of wrenching on the CBZR-650 indeed!

As you all saw, just in the nick of time and despite my best intentions, Rick explained to me that a cold chisel and framing hammer weren't the proper duo of tools for doing valve work. He then showed Luke and I the correct technique of lapping in valves with the time honored suction (sometimes) cup-stick-thingy and black, wet volcanic sand-like valve lapping compound:



After all of the pits were worked out and we were left with the tell-tale consistent light gray stripe on all eight valves and seats, we moved onto the bottom end. Luke discovered that the ignition side-cover wouldn't fully seat onto the crankcase, so the first order of business was modifying a spacer that helps hold the Dyna 2000 ignition rotor on :



Next up was some more wrench-spinnin', circlip removin' and case crackin'. Here's a photo of the bottom end completely disassembled with all of the parts ready for cleaning, inspection, cuss-mumbling, and reassembly:



Besides a bad bearing surface on the end of the primary transmission shaft (which was replaced with a perfect spare shaft from Luke's spare parts stash) everything went smooth as can be, but there's much more to tell...

I had a great weekend and it was made even better by the opportunity to finally meet the Loud Al. As all of you know, he's one helluva good guy and we wouldn't have gotten anywhere near as much done without him there.

Lots of assembly, and a little fabricating this weekend.


Start with lapping the valves.








Allan took the good pictures.



The first transmission shaft had some pitting on one of the bearing surfaces, so we swapped in the shaft from the new 550 motor. Of course, the oil passage had to be cut.





The kickstarter is half of the reason for doing all this motor work. Here's the shaft.









Bottom end done, waiting for the top end parts: the cylinder is at a machine shop getting decked, the new rings need to be gapped but otherwise it's ready to bolt together.







So, on to the swingarm. It's going to be built almost from scratch. Rick cut off the pivot tube:





I did some practice of cutting the tube for the new swingarm. I can't remember who or where, but someone on this forum mentioned that using a rod in the center of a hole saw instead of the pilot bit worked really well, and they were right.




Good fit on the practice piece, time for the real thing.

Pilot hole:


Small tool, big job. But it worked.




The pilot hole is cut:



And then the main hole:


The tube will be cut in a few different spots and then welded back together to make the swingarm.

And that was about all for the day, besides filling up three big bags of trash to haul out of the shop. Not really picture worthy.

...but any reason to use the hole saw in the handheld drill? It looks like the pilot was created with a drill press.


Otherwise:

HOLY COW THIS IS AWESOME!

Looking great. I hope I get to come up there one of these weekend's to break stuff...I mean, help out the build too!

I was just asking Luke yesterday if we might see you, he said that between working overtime and building your MK1 Rally Suby, you were swamped. Hope we get to see you sometime soon, would hate to have you miss all the fun.

Sooner, or later, this is bound to wind up being a caption for different picture.

This may be evidence of Luke's very dry wit....

The cordless drill can turn much slower than the drill press, which is good for the hole saw bit. Here's the post: http://advrider.com/forums/showpost.php?p=19947221&postcount=1695

Jdrocks wasn't kidding about the binding either, I've got a tender spot on my ribs where the drill's battery pack smacked me a few times.

Ahhh...added to my vast knowledge base...

Luke came over Saturday and started fabricating the swing arm, as you can tell from the photos, he made pretty good progress. I'll post the pics and let Luke weigh in later with the commentary.

Swing arm pics;









And Luke's new toy;

Why are you making the swingarm out of multiple pieces of box tubing? Doesn't look like it would be and harder to drill offset holes for the swingarm pivot that would give you the angle/clearance you need? Luke, if you want to send me some dimensions I can help you figure that out?

A straight tube won't work because the shock mounts are going to be under the center of the swingarm. Here's the cross section of the parts to be avoided at the centerline of the swingarm.

Very nice TIG torch Luke! Is the little knob towards the upper end of the torch handle a shielding gas control valve?The swingarm is coming along nice as well.

Only problem is we need more updates! I'm sure I'm not the only one having CBZR-650 withdrawals...

Yeah, I'm having withdrawal too. I got a little work in last week but have been busy since then.


From last week, a little more swingarm work:

Start with making a tube to simulate the hub with extra spacers.


This'll be a lot faster when I get the parting tool working.







Then tack some parts together.




More stick welding. I like.



The welds turned out as flat as the tube stock.



It turned out pretty well, with the axle and swingarm legs clamped together they were within 1/2mm at the swingarm pivot tube.

Cutting the cross brace.


The legs needed a bevel cut into them, and that was the last thing to do. These cuts were tricky, and I had to learn a few things about chop saws and metal tube. Chop saws need pressure to cut. Long flat cuts don't work. Metal tube has internal stress. Slit it long ways and it will spring out. Not the end of the world, but that'll be something to fix next time.

Understand what you're doing with that swingarm now. Thanks for clarifying. For any precision cuts, you might want to try scribing lines on all four sides and then using a 4-4.5" angle grinder with a cutoff wheel. It's almost impossible to hit perfect angles on a chopsaw.

You must have a much steadier hand than I do. I always do way better with the chop saw. Start with a decent one and take the time to square it up. It's a moot point anyway because the accuracy of the swingarm doesn't depend on the accuracy of the cuts. It just makes the fit better for welding.


The half mm was the difference in width between each end of the swingarm with the axle end bolted up and the pivot end free. A 0.05 degree error.

Like your build up so far ..Thanks Have a question on the front end .. which tripple trees did you use for the forks ? did you have to modify the neck bearings to fit ?