Sunday, November 10, 2013

CB500T - The Resurrection

After reassembling the 450/500T frankenstein, I was left with alot of spare parts, and the remains of the 500T parts bike. I didn't have any takers on craigslist, so rather than scrap it all or have it clutter up my shop, I decided to reuse all the leftovers to build a new race chassis. I have no idea what I will use it for, or even what kind of fuel it will run on, but at least it puts alot of junk to good use!

The hulk

Stripping the front forks.

Pressing in new fork seals

1 down, 1 to go

Forks, new tire, and center stand

Rebuilt a spare wheel and installed. All that's left is a new tire, reinstall the fender, and I can put it in storage.

Friday, November 8, 2013

KZ400 Diesel - Rebuilding the Electrical System

The last major repair I wanted to make to my diesel bike, before putting it into winter storage, was rebuilding the wiring harness. I got the bike as a bare frame, so I had to make a harness from scratch. At the time, I had no experience building an electrical system, nor did I know what proper wiring practices were. I was a simple mechanical engineer, and all I knew was (shudder) electrical tape, zip ties, and hard plastic spade connectors.

Since I didn't originally intend to make the bike road legal, the first system was a crude total-loss setup to turn the headlight and taillight on. As the project progressed, I added new circuits and zip-tied them to the original wires. By the time I had finished the bike, I had added brake lights, a horn, and a charging circuit, and the harness looked like this:

Good luck tracing THAT out
Why on earth would I put the fuse THERE?!

Different angle, just as bad...
 Obviously, something needed to be done. I had used a mash up of different wire colors, none of which matched, and it was nearly impossible to find any shorts that occurred. To fix the problem, I bought 5 different wire spools, a box of Honda-style bullet connectors, a real crimping tool, and set to work.

This is a beautiful sight to me. That is why I'm a geek.

Much Better

There! Not bad for a mechie.

Tuesday, November 5, 2013

Carburetor Modification Part 3

Jetting a non-standard carburetor for an engine, especially when no one has tried the combination before, is an extremely time-consuming process of trial and error. I reasoned that the original jetting would be a close match, or at least a decent starting point, because the three carbs had previously been mounted to a Triumph Trident, with each feeding a 250cc cylinder. What I didn't take into account though, was the possibility that the previous owner may have jetted it TOTALLY WRONG.

This is becoming an annoyingly familiar sight...
 Mikuni carbs have three main fuel circuits: the pilot circuit for 0 to 1/4 throttle, the midrange circuit for 1/4 to 3/4 throttle, and the main circuit for 3/4 to full. After weeks of fiddling, testing, and tinkering, I have determined that the pilot circuit was JUST ABOUT right, the midrange was extremely lean, and the main was extremely rich. In fact, the disparity between midrange and main was so large, that it created the illusion that it was jetted correctly, but had an air leak/low range stumble. The rich main supplemented the lean midrange and they compensated for each other, while causing poor power and a tendency to stall at low throttle.

Needle Jet Swap

Seriously, I've had enough of propping the tank up...
I think I'm pretty close to getting it dialed in mostly right, and will post the final settings when I have them. Though, I think I should bring it in to a tuning shop and have them doublecheck it...and also rebuild the brakes....possibly replace the clutch plates...sooner or later it will be "done"!

Saturday, November 2, 2013

Loring Timing Association 2013

This past July we made our annual pilgrimage to northern Maine for the Loring Timing Association's Maine Event. It is held on the former SAC runway at the decommissioned Loring Airforce Base; 12,000 feet of smooth, flat asphalt. It is so flat that, because of the curvature of the earth, you cannot see end-to-end!

This year, we set records with both the diesel bike and the CB450/500T Frankenstein. The diesel managed to just break 60mph, and the 500 was limited to 92.3mph due to nearly overheating from an intake air leak. I'm posting some of the pictures here, and the rest can be found at my friend's smugmug page:

RIP Bill Warner

The Perewitz's and their monster.

Somewhere in there is a BSA Scrambler

A sample of the madness