Another 81 GPZ. Losing the fat.

The Gringo wrote:

Hey Lou when you photoshop paint on a bike is it fuel resistant?:laugh: Just kidding the bike is coming along nicely.

Only when you use the factory color! :laugh:

steell wrote:

Miller Synchrowave tig

I want one of those, but unfortunately so do a lot of other people and it keeps the prices way up there

Bet it will be a gorgeous hot rod 550 when you're done

Tell me about it. I can't find a decent used Miller or Lincoln tig anywhere for under $1000. But I think I'm going MIG anyway. I'll mostly be welding outside so flux core may be more what I need. I guess the gas blows away too much in the wind.

I'm probably going to get the Hobart Handler 140. It's wire feed flux core and solid wire with gas. It comes with everything except the bottle, and it under $400.

I've been playing with a Sears hobby welder I found in the attic. It drives me crazy, but it actually worked on some exhaust pipe. 6013 stick.

Went to home Depot and bought a sheet of acrylic (Lucite, Plexiglass). Started experimenting. 18"x24" .093 thick, about $8

Do not drill fast. You need a cordless drill at the lowest speed... like 60 rpm. Yes one revolution per second. Do not let the bit get warm because it fuses to the plastic then it shatters.

Forget cutting with a jig saw. It just shatters. I also tried scoring it with a utility knife and snapping it. That took forever, and the snap can fracture crooked.

The best way to cut acrylic, I found was using a home made hot knofe. I took a propane soldering tip and sharpened it to a knife point. It cuts fast, but not all the way through. You still have to snap it, but it breaks much more cleanly. You have to be careful not to overheat the acrylic.

Clamp the plastic with a metal straight edge on top of a metal plate, preferrably aluminum. That takes the heat away from the plastic quickly so it won't bubble away from the cut line.

To bend acrylic, I just used a propane torch since I didn't have a heat gun. It works ok, but you really have to heat it slowly . I clamped it between two pieces of wood. I made a mistake in this photo. The upper piece of wood should be set back about 1/4" to 3/8" so the plastic will heat slightly before the bend. On this trial, the bend happened away from the wood form. I routered the lower wooden form to a 1/4" radius to make a nice smooth bend.

Wood is good because if it starts to smolder, you know it's too hot, ha. The plastic will blister. (It's actually embedded water that boils to form the blisters.) You need to back away with the flame and move it quicker, back and forth, across the bend line.

For polycarbonate (bullet-proof glass, Lexan) forget the torch... it's too hot and will almost always blister. It requires a heat gun, but works the same way, with one major difference. Because the surface is softer, it mars very easily. I ended up with the imprint of the wood on the surface. It's not a problem for my application since I'll be sanding it and painting it. You will want a layer of very soft fabric etc between the wood and polycarbonate to prevent marring.

Always bend away from the heat. It takes a good 5 minutes to heat the piece properly. The heat gun can even take longer. The smaller the piece, the faster.

This one is acrylic.

So here's the finished acrylic test piece.

Only buy the cheaper acrylic for test pieces. It cannot be the final product because it just loves to crack. Acrylic is optically more pure than glass. It's harder than polycarbonate, but it comes with the tradeoff that it's weaker and cracks much easier. Polycarbonate (aka Lexan) is softer and scratches easier. It has a slight tint to it, but it has the huge advantage that it will bend instead of break.

One way to tell if you have acrylic or polycarbonate is to look at the edges. On acrylic, the edges will be brighter than the rest of the piece. The pice will be clear with white edges. On polycarbonate, the edges will be darker, like with glass.

The final piece should be polycarbonate and it works slightly differently. To cut it, a utility knife works best. Score it about half way through (it's easier than acrylic because it's softer), then snap it carefully. To bend it absolutely requires a heat gun at about 1000 degree setting. (Propane is up around 3000 deg... way too hot.) Polycarbonate drills much easier too. You don't have to go as slow as with acrylic, just don't go too fast or it will overheat and get gooey.

So I re-made the tail piece with Lexan (18" x 24" by .093 thick is about $15). Then I put in the aluminum mounts with aluminum and pop rivets. Make sure the holes in the Lexan are one size larger than the rivets to allow for some expansion in the rivet. Notice the plastic is a little darker than the acrylic piece.

Here's a cool shot from the rear.

Next was the seat pan. It's 1/8" aluminum bent by hand on wooden forms. The rear bend was done without anything special, but the side edges were tougher. The trick on the side bends is on the underside. Before I bent it, I took a 1/4" thick grinding wheel and cut a groove along the bend line on the underside. I cut about 1/32" deep. This forced the bend to be straight, and it also controlled the bend nicely so there are actually 2 bends right next to each other if you look very carefully in person. This gave a very nice machine-bent look to it.

Other angles with the headlights.

What a great write up and very cool looking tail.
I know you plan on painting it but I must say the transparency is pretty wicked looking.:woohoo:

Any recomendations on what plastic to use for replacing the winshield? I have a heat gun so it is on my list of things to try.

Wow Lou, where do you live?? Im movin next door! Great lookin, cant wait to see the results!
Lou, I was told you would be the guy to ask, would you have a spare throttle assembly laying around? I have kz550a3, missing the starter button. Was wondering if you even had a spare start BUTTON, or horn button?