Bride of Frankenstein - a cure for leftover parts cluttering the workshop.

Mini Bike & Go-Kart Parts

mustangfrank

Well-Known Member
#61
I realize that hydraulic brakes are not at all an "old mini bike" thing, but I began rebuilding the bike's goofy Honda Inboard Disk this morning and figured I'd post a couple photos.

The caliper was already seized solid when I got the wheel almost 16 years ago, and it had been sitting dry, with no line connected, in a dusty corner of my garage ever since. Clearing the line took both master cylinder pressure from one side and a mityvac pump pulling on the bleeder from the other. Eventually, a big black plug of gook appeared in the bleeder tube. Once I pushed that through, I closed the bleeder and had no problem pumping the pistons out. Overall, it's in surprisingly good shape. There was a lot of crusted-on crud in all the crevices and some jellied residue inside, but I had been prepared for much worse. The pistons are probably reusable, but I already purchased new ones, along with new seals and boots. Now it all goes into the ultrasonic cleaner!

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Not that unheard of, I've seen a few run the little sealed brake systems swapped off of newer bikes. Digging the little 2 piston caliper.
 
#62
Ultrasonic bath, then soda blasted, back in the ultrasonic tank again, then a couple coats of Eastwood Brake Gray. The brake caliper is ready for reassembly, but the brake pad locating pin disappeared at some point over the last 15 years, so that's on order and further assembly will have to wait.

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Since my trailing axle arrangement puts the fork legs farther forward relative to the wheel hub than the stock VTR250 forks were, I had to trim off a portion of the air scoops on the caliper side for clearance. In the photo below, the intake scoop is the original height at the extreme right, and the red grease pencil shows how much I removed from the rest of it. It will definitely need some additional dressing before it gets painted, but I'm happy with how it came out. Concerning myself with aesthetic finishes is still a long way off.

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I74

Well-Known Member
#63
Ultrasonic bath, then soda blasted, back in the ultrasonic tank again, then a couple coats of Eastwood Brake Gray. The brake caliper is ready for reassembly, but the brake pad locating pin disappeared at some point over the last 15 years, so that's on order and further assembly will have to wait.

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Since my trailing axle arrangement puts the fork legs farther forward relative to the wheel hub than the stock VTR250 forks were, I had to trim off a portion of the air scoops on the caliper side for clearance. In the photo below, the intake scoop is the original height at the extreme right, and the red grease pencil shows how much I removed from the rest of it. It will definitely need some additional dressing before it gets painted, but I'm happy with how it came out. Concerning myself with aesthetic finishes is still a long way off.
That caliper looks awesome !
 
#65
My spare brake line is just a couple of inches too short. Damn.

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I taped the cheap-o plastic fenders in place, just to get an idea how they'll look. I'm not really digging the super angular front, but it's what I'm stuck with, so it is what the bike is going to have. All the clutter around the bike in this shot doesn't help (my workshop space is pretty cramped and desperately in need of a good reorg/tidying up).

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#66
I'm working on the exhaust. Since I don't have $600+ dollars to drop on a proper tubing bender and dies, I bought a used, 1" diameter electrician's conduit bender for $30. Unfortunately, I had no idea how big it would actually be. It's a monster.
Here's my first attempt:

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The radius of the bend was way, way too big for my purposes. That pipe is exactly where your left thigh is going to be when you put your feet down at a light. Ouch!

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So, I bought a pre-made header pipe. It had a much tighter bend, which is good, but this one pointed straight at the rear frame tube. So, I cut it down and matched it to another section of tube that I had bent with the conduit bender just slightly.

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It tucks in so much better! It will still need a heat shield, but definitely a workable fit.

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I have most of the intake plumbing cut to shape, too. Once I have all that ready to go, I will drop all the parts by my local welding guy and have everything pieced together properly.
 
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#69
After a disastrous attempt to weld up an intake tract myself (which I wisely refrained from photographing), the exhaust pipe and intake components were dropped off at my friendly neighborhood welder this morning. He expects to have them done in a week or so.

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I also got a bit more done on the front brake. The VTR250 didn't use an actual brake stay. Instead, there was a boss cast into the fork lower that engaged a slot in the brake plate when the wheel was inserted. Not only do my forks not have that brake boss, but the forks are now forward of the axle anyway. That's actually a good thing, because it frees up that space for an additional stay assembly. The stay arm is 7/32" (5.5mm) thick steel. It mounts to the axle at the bottom and has a 90-degree bend on the other end for transferring brake force against the back of the fork slider. I cut and ground an alloy block to be a tight fit inside the brake panel slot. I still need to mount the block to the arm. I am planning to use a pair of M8 x 1.25 socket head screws with heli-coil inserts in the alloy block for strength. I'll also make up an additional bracket that will tie the top of the plate to the fender mounting bosses for a little more strength (and because the brake plate could theoretically rotate the other way when the bike is rolled backward).

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