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1981 gs750 (gs750e) Retro Racer project

Where did you get the muffler?
I have a bike with a Devil exhaust and I wonder if this would fit?
What's the inner diameter of the muffler?
Ideally it should be around 75 to 78 mm!
 
https://www.ebay.com/itm/61mm-Black...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

This is the one. I was looking for 63mm in size, but i think this is the biggest. You could use something like this if you coud find it with the right measurements:

https://www.ebay.com/itm/Motorcycle...454798?hash=item23a72aca8e:g:dL8AAOSwvAhbZ7C8

Many thanks!
I can tell you that my Devil muffler looks identical from a fabrication standpoint and I didn't even try it without a dB killer and it's still loud !
 
Tried to make the tube at the end a little wider by hammering a stepped tube inside it. This clipped two of te rivets holding the muffler together. I drilled out the last one and took it apart.

Clipped rivet by Lars Krogh-Stea, on Flickr

Stuffing by Lars Krogh-Stea, on Flickr

Hammered lightly on the inner ring to set the pieces together.

Separated by Lars Krogh-Stea, on Flickr

Put it back together with new pop rivets. From now I'll treat the two parts as one and mask off the bend before I powdercoat the muffler.

Back together by Lars Krogh-Stea, on Flickr
 
Borrowed the cnc-router again. This time for the top triple. Did some prototyping in oak for speed.


L by Lars Krogh-Stea, on Flickr


L by Lars Krogh-Stea, on Flickr


Ordered gear indicator and warning lights from ebay. The gear indicator was awesome, but the warning lights was a big disapointment :D For some reason they were all blue. Waiting for another shipment with the usual blue, green, red and orange. I will also cut down to four lights and have one common light for the indicators. The reason for the hole next to the gear-indicator is that I forgot to alter the settings before testing on the oak. The aluminum I've bought is 8mm thicker and i trilled 6mm down into my friends router table :o


L by Lars Krogh-Stea, on Flickr


L by Lars Krogh-Stea, on Flickr


The reason for the uneven outer edges is that I went too fast and broke the end mill piece. Had to use a band saw to finish it off. It's only for testing so it doesn't really matter, and I have more end mills at home.


L by Lars Krogh-Stea, on Flickr


L by Lars Krogh-Stea, on Flickr
 
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I was struggling to find a good placement for the speed sensor. I've seen some people mount them in the rear brake, or under the front fender, but I will try to modify the original speedo-gear unit. That way I won't have to machine a spacer to replace it. I will drill a hole inside the original hole to place the pickup perpendicular to the magnet. Then I'll grind off some off the original gear so the magnet will sit flush.

Sensor4 by Lars Krogh-Stea, on Flickr
 
Thanks, Sam :)

I sodablasted the carburettors and dusted them of afterwards with compressed air. I thought I was careful not to get any soda inside them, but my father said I should open and clean them anyway.

2018-09-08_08-12-08 by Lars Krogh-Stea, on Flickr

Glad I did, because he was right. Also, although I've adjusted the needles in my zx7r and knew there were diafragms in there, I didn't know the big oval channel in the inlet was directly connected. I imagine if you blow hard enough directly in there, you might rupture the diafragms. Mine where fine, but I will clean my carburettors some other way the next time.

Soda by Lars Krogh-Stea, on Flickr
 
Sometimes the build finds its own path and I have to tag along to see where the build goes. I've been good at spending time on planning to minimise the need for doovers. But when I thought I found a similar exhaust on the internet as I had stowed away 3 years ago, I was dead wrong. Measurements was wrong and after countless tries to make the new exhaust look good on the bike, I gave up. I then decided to make my own. The goal was to have the same amount of stainless perforated tube as in the Kercher.

43862371024_b48d24a090_c.jpg
Exh 5 by Lars Krogh-Stea, on Flickr

Lucky me had some stainless perforated tube laying around.

Exh 4 by Lars Krogh-Stea, on Flickr

Took some half inch aluminum to the lathe and made the end piece. It is stepped with the same thickness as in the perforated tubing. Did also put in some set screws to secure it.

Exh 1 by Lars Krogh-Stea, on Flickr

Packed it:

Exh 2 by Lars Krogh-Stea, on Flickr

And hammered it gently in. All that is missing is a screw on the backside to keep it from moving. But I did stamp in my initials just for fun.

Exh 3 by Lars Krogh-Stea, on Flickr
 
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Hi Lars,

The original wiring has a 15 amp fuse between the regulator and the battery.
It's a separate fuse as the other circuits have their own fuse.
It's mandatory as you could have a short say from a headlamp that would kill you regulator immediately.
Have you considered using the M-Lock from Motogadget?
I installed one yesterday and it works great.
BTW I believe you should also consider the diagram from a wiring harness perspective.
One for the rear of the bike, one for the front , one for the dashboard etc...
Great job!
 
Hi John :)

I've made a new diagram with the 15 amp fuse for the charging circuit and some other modifications. All ground is now leading back to the battery via wires, the oil pressure wiring is corrected and the alternator has three wires. The m-lock is really cool and i have an rfid-circuit laying that a was planning to use. Since I have the M-unit blue I'll use the bluetooth for keyless. I'll check out your builds later :)

Noisemaker_koblingsskjema by Lars Krogh-Stea, on Flickr
 
I like it so far! I think it's cool you're using your router table to prototype some of the parts. I have a Shapeoko 3 and use it from time to time on stuff like this. Let me know how that aluminum piece looks after some time in the exhaust. I've been told not to mix stainless parts with aluminum parts unless one or the other has been coated (paint or some other insulator). Galvanic corrosion occurs when the two are in direct contact. I've never seen the affect of it personally but I'm curious to see what happens after a while. Let us know if there are any signs of corrosion or if it's not a big deal!
 
I like it so far! I think it's cool you're using your router table to prototype some of the parts. I have a Shapeoko 3 and use it from time to time on stuff like this. Let me know how that aluminum piece looks after some time in the exhaust. I've been told not to mix stainless parts with aluminum parts unless one or the other has been coated (paint or some other insulator). Galvanic corrosion occurs when the two are in direct contact. I've never seen the affect of it personally but I'm curious to see what happens after a while. Let us know if there are any signs of corrosion or if it's not a big deal!


Thanks :) I didn't think about the reactivity between metals, but it makes sense. There's not much left of the driving season here, som I'm lucky if I get to test it this year.. But I will keep an eye on it and post pictures if anything interesting happens.
 
I posted the wiring diagram in the electrical section and got some pointers and ideas. This is the final rendition of the diagram. The wires are not to scale, either by length or thickness, but the diagram shows how things will be connected to eachother. The turn light switch is a returning two way switch, the others are push buttons.

Noisemaker_koblingsskjema by Lars Krogh-Stea, on Flickr
 
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