Saving a 1980 750 twin.

  • DoctoRot
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27 Jun 2015 21:54 - 27 Jun 2015 21:56 #678564 by DoctoRot
Replied by DoctoRot on topic Saving a 1980 750 twin.
I have been super busy trying to finish up two bikes to sell so that has been occupying my time. I finally finished the seat, but i still need to rivet a few more places to get the edge to be even. Very pleased with how everything turned out considering this is only the second seat i have ever made. The tricky part was getting the seam on the seat to align with the stripes on the tank. The side covers mounts were badly cracked so when i repaired those with fiberglass i extended the edge to fill the gap between the frame. Next up is to finish the swingarm, make spacers for the wheel and arm. and do a little frame bracing.






Last edit: 27 Jun 2015 21:56 by DoctoRot.

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28 Jun 2015 01:02 #678575 by DoctoRot
Replied by DoctoRot on topic Saving a 1980 750 twin.
Thinking about how i want to detail the engine. paint n the engine was done very poorly so i'm going to soda blast it off. i might paint the cylinders and head black. with everything else bare or polished. Thinking about doing the polished fin edge if i do them black. but it kinda looks funny with few fins getting the treatment in one spot. Maybe ill do the fin below as well. thoughts?

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28 Jun 2015 01:30 #678576 by missionkz
Replied by missionkz on topic Saving a 1980 750 twin.
I prefer all the outside edges of the fins to show semi-polished aluminum if the cylinders and heads are painted satin black.
I don't care for a gloss black engine.... partial black or otherwise.

Either way, when polishing the fin edges, it is had to make them all look consistent though.... some of cooling fins in the head castings are pretty rough.

Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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28 Jun 2015 02:54 - 28 Jun 2015 02:55 #678580 by DoctoRot
Replied by DoctoRot on topic Saving a 1980 750 twin.
I dunno, sometimes i see the cylinder done as well and i think its a little over the top. plus getting the cylinder fins to match the head fins would not be easy. I did just a proper job polishing them back and i think it looks a lot better. still up in the air though. kinda reminds me of the new thurxton.
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Last edit: 28 Jun 2015 02:55 by DoctoRot.

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28 Jun 2015 04:57 #678584 by 80B4
Replied by 80B4 on topic Saving a 1980 750 twin.
I have cut the fins on several heads and cylinders on my cnc controlled mill. It gives them a uniform look that you can't get if you do it by hand. BMW and Harley machine cooling fins too.

1980B4 1000
1978 Z1R
1978 B3 750

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28 Jun 2015 09:36 #678598 by missionkz
Replied by missionkz on topic Saving a 1980 750 twin.
Yup but I've owned a few and always had a soft spot for Brit bikes....

Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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28 Jun 2015 22:27 #678670 by Jbosh
Replied by Jbosh on topic Saving a 1980 750 twin.
Doc, how you cleaned up the fins here looks really sharp in my eyes! I think you are bang on! Although what's going on with your dohc badging on your case? Nice work so far!

As long as I get to learn something, I'm happy!
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03 Jul 2015 16:42 #679307 by DoctoRot
Replied by DoctoRot on topic Saving a 1980 750 twin.

Jbosh wrote: Doc, how you cleaned up the fins here looks really sharp in my eyes! I think you are bang on! Although what's going on with your dohc badging on your case? Nice work so far!


Thank You. Im contemplating casting a new timing cover. I took a mold off the original which i will cast in wax eventually. I don't know what to do on the face of it. Right now options are "DOHC", "KZ750", or "750T" any suggestions are welcome. I also don't know what material to cast it in. I have never cast aluminum before, but have a good deal of experience with bronze. Heres a bronze belt buckle i cast a few years ago.
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03 Jul 2015 16:52 - 04 Jul 2015 00:53 #679309 by DoctoRot
Replied by DoctoRot on topic Saving a 1980 750 twin.

80B4 wrote: I have cut the fins on several heads and cylinders on my cnc controlled mill. It gives them a uniform look that you can't get if you do it by hand. BMW and Harley machine cooling fins too.


You and your fancy tools... Im quite jealous.
Last edit: 04 Jul 2015 00:53 by DoctoRot.
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04 Jul 2015 07:49 #679377 by 80B4
Replied by 80B4 on topic Saving a 1980 750 twin.
When I carve a new ignition cover for my B3 I'll do one for your bike Vic.

1980B4 1000
1978 Z1R
1978 B3 750
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04 Jul 2015 07:59 #679379 by SWest
Replied by SWest on topic Saving a 1980 750 twin.
We did sand casting in metal shop. As I remember aluminum melts at 2500*. You should be able to do it. I'd like to see how it comes out.
Steve

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04 Jul 2015 09:29 #679388 by 80B4
Replied by 80B4 on topic Saving a 1980 750 twin.
The melting temp of Aluminum is between 860° and 1240° f. depending on the alloy. There are lots of utube videos on back yard aluminum casting. I did a lot of foundry projects in grad school, it was fun!

1980B4 1000
1978 Z1R
1978 B3 750
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