Stu's KZ1100 #4... rear end...

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Prof
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Stu's KZ1100 #4... rear end...

Post by Prof » Fri Jun 27, 2014 11:22 pm

We've set up Stu's front end so now we can head down to the rear.
We purchased some new 300mm shockers from the Café Racer Shop (great prices). They have 12mm diameter holes in the eyes and Stu's machine's shocker mounts are 14mm. Glenn has come up for a bit of fun in the workshop and gets the job of machining up some wearlon to replace the rubbers in our shockers.

First job is to press out the old ones. To do this he machines up a drift just slightly smaller diameter than the shocker eyes and out they come with no damage; might get used in something else one day...
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Eyes are measured and 14mm bushes machined up. Notice the locating groove in the centre...
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Pressed in the with same drift...
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Shockers now almost fit. Wearlon compresses slightly when pressed in and need a quick redrill to fit... and they now do. Good job Glenn...
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We need to set up the chopper's final height at the rear. Stu wants it long and low, but we have to compromise a bit as this motor is very wide. We also need to make sure the shaft's universal joint won't bind on full compression. We do this by getting it to bind (listening to the changed sound as the wheel is rotated) and then backing off a bit. Chopper can now be blocked up plus ½" to allow for bike weight acting on shockers...
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A couple of scrap pieces of flat bar are drilled to simulate the shockers. Shocker mounts will need to be raised to allow chopper to sit at the height we want. This is ok as Stu doesn't like the stock back end. It will get "the chop"...
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To cut the rear tubes off evenly we need to measure each from a known point that is equal each side of the bike... the centre of the swing arm shaft fits the bill fine...
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Marked and ready to cut. Each tube is ringed with a pipe cutter to create a guide line for a perpendicular cut.
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Here they have been cut and a couple of sleeves made ready for joining in the new pieces of tube. On front down tubes and the bottom tubes of a rigid I use slugs, but sleeves will be fine here because there is far less stress in this location...
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Two pieces of tube have been cut and tapped on. This particular model has uneven bends just behind the swing arm pivot. These need to be heated and rebent to both meet the shocker mount points.
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Our two pieces of flat bar are set up to simulate the shocker angle Stu wants. Ideal shocker angle is when top and bottom eyes are the same distance from swing arm pivot, but look a bit better with some extra slope at the front...
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Here's how we get both bars even angle. Easily made out of an old aluminium level...
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The Chopper Shed seems to have become dog friendly. Kevin's and Stu's dogs have established themselves, Stu's mutt even getts his own padded grandstand view of all the goings on...
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heating and bending the tubes outwards...
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Bending them upwards to follow line of guard. Levels are used as well as sighting to get everything even. When you are fabricating, take time to get things right even if you have to stop to make some tools. I have had choppers in the workshop that were welded up so crooked they were a time consuming not to mention thoroughly annoying to modify.
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Stu likes the idea of the rear frame tubes following the guard, so now we get into some serious bending. I would normally do it in a tube roller, but it wastes a lot of material and I don't have enough for the job. We'll get out the gas instead. Here we are making a pattern using some lead pipe I keep for this purpose...
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First tub is bent to pattern and then used as a pattern for the second. Once they are pretty right we do some fine tuning to get each curve smooth and the same...
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Testing the two tubes using a flat surface to push the two straight sections against... the most accurate way to get them 'right'...
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Installed and end up spot on. Nest we'll mount the guard and do top shocker mount. Then seat rails. Rear of tubes are fairly bulky and we have a trick that we think will slim them down, provide sissy bar and rear light mounting and look durn schmick.
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Chopit'nrideit... Prof

Bearcx
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Re: Stu's KZ1100 #4... rear end...

Post by Bearcx » Sat Jun 28, 2014 10:19 pm

Nicely done. Lookin' more like a chopper every day.
The brave may not live long, but, the cautious do not live at all.

Prof
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Joined: Sat Oct 22, 2005 3:54 pm
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Sun Jul 06, 2014 10:53 pm

Time to mount guard and then set up shockers.

First we make sure chopper is level and then level up rear sub frame tubing we have just set up...
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Stu as chosen this flat guard, especially because he likes the rear lip (Reminds him of his German helmet). I encouraged him to use a more curved rear guard as I thought it fitted in better with overall smoothly flowing lines of the rest of the bike; and we could have built a similar lip on that. However Stu is deadest on this one and it will look fine...
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Rearmost guard mount now cut out of 30 x 5 flat bar and centre being marked off tyre centre so guard mounting holes can be drilled...
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Holes drilled and the mount welded in (on the top side anyway). We will use M8 bolts screwing into threaded plates welded to underside of guard. Holes therefore are 10mm to allow final alignment. Doesn't matter how had you try, drilling exact size holes rarely works... seems like exactness doesn't always 'look' right! the front.

You can also see the front mount has been cut. This is made from some 50 x 10 rectangular tube. The narrow edges are round, so it looks great and being rectangular and hollow adds structural strength...
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Being tubular we need to make crush tubes or the bolts will squash the tube. They are made in the shape of a top hat... forgot to take a pic. Stewart is keen to learn to weld. This is a good opportunity for him to have a go with the gas and bronze rod. He picks it up quickly...
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This is the bolt head side... the rim of the top hat...
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... and the underside that is against the guard. It doesn't need welding as the pressure will be taken up by the 'barrel' of the top hat, the edges here visible...
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Holes can now be drilled in the guard. We mark and drill on at the bottom. Then put a piece of rod through it and drill the second hole. Leaving the rod in the bottom hole, we can hold the guard hard up against the rear mount and mark and drill it.
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Guard bolted in. Drilled plates under guard will be welded later when we take the wheel out. Now for the shocker mounts...
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Stu cuts the mounts off the stock rear sub frame and then reshapes them to fit our new frame. Because our tubes angle inwards, we also have to cut the mount just in front of the bolt and bend it so that we can keep the shocker bolts parallel to the bottom bolts. A little bit of judicious grinding and bending gets them both fitting. Missed a final pic of the cut and bent mount. Sorry!
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Now for a lot of measuring. Mounts need to be the same distance back.
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They need to be perpendicular to the centre line of the chopper. They need to be horizontal. I tack them first so they can be moved and then realign retack and recheck. All ok and they get welded in...
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Shockers finally mounted and the chopper at last on it own wheels...
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I told Stu to make an interesting face for this shot... and he did!
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Seat rails next...
Chopit'nrideit... Prof

Prof
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Tue Jul 08, 2014 11:00 pm

Today while working on my own CB chopper upgrade and helping a couple of lads set up a bulbar with winch, phoning orders, keeping an eye on kevin's YamBeeza build, I helped Stewart do his seat rails. We were all just about tripping over each other but no injuries were sustained!!!!

I got Stu to cut a couple of pieces of 29mm pieces of tube 450 long. He wants to sit as low as possible, so we set up the battery and allowed 20mm clearance above it.
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If we used straight rails, we would have a bit too little support for the shocker mounts. The solution is quite simple and also fits in nicely with the rest of the chopper's curves... curved rails. A sharp bend at the rear of each rail gives support to the rear tubes close to the shocker support and overlaps its reinforcement. the bend also means that the length of weld is three times more than a slightly angled butt joint... adding a lot more strength.

First tube bent. The pointer you can see on the left allows Stu to bend the second tube exactly the same...
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Front of first tube ground to be a close fit. Any gap will cause the weld to pull and stress the frame.
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Rear of tube cut and ground to fit... Stu had a hard time with this one so I did it for him. Joins like this are a bit tricky and take some patieince. Stu will also make small gussets at both these joints on each side for tidiness and strength.
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Second tube bent and ready for marking. We leave an extra 3mm each end to play safe...
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For final fitting the chopper is set level and both front and rear of the seat rails are trimmed until both are perfectly level side to side. This final fitting took almost as much time as the rest of the shaping...
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Seat rails welded in...
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Job finished. Stu just needs to put the shocks back on and the bike is fully on its two wheels. With the exception of a few gussets and final welding, the frame construction is complete.

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Stu came in all excited while we were having tea... reckons he's spent the last 20 minutes sitting on his chopper, woaking around it and looking at it from all directions in a state of semi euphoria!!! ie he likes it!
Chopit'nrideit... Prof

Youngblood
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Re: Stu's KZ1100 #4... rear end...

Post by Youngblood » Wed Jul 09, 2014 12:10 am

She is definately looking good, no wonder Stu is a happy man
8) 8) 8)
Youngblood

Bearcx
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Re: Stu's KZ1100 #4... rear end...

Post by Bearcx » Wed Jul 09, 2014 3:04 pm

Love it.!! All that work, and a very cool looking scoot, Stu should be proud to ride that around. Great stuff.
The brave may not live long, but, the cautious do not live at all.

Prof
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Thu Jul 10, 2014 8:21 pm

Thought I'd give Stu another bit of practice on the lathe. The rear shocker top bolt shafts are too wide for the shockers we are using. Stu is keen on a few brass highlights, so a couple of brass spacers should look pretty schmick...

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Showing Stu how to set the tool holder at an angle...
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Stu gets stuck into it...
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Close up of the cone shape being machined into the brass spacer...
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Brass spacer attached. Stainless washer is a size too small, because the outer diameter is correct. I mounted each stainless washer in a cut out I have in my drill vice and drilled out the centre to the correct size. End result looks pretty cool... Because the thread is a metric fine, we can't use a stainless acorn nut, but I have suggested to Stu that he machine some up out of some hex stainless. We'll see...
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The frame rails will benefit both for strength and looks with a couple of gussets front and back. Stewart marking up the front one...
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Front ones taped in place ready for welding. Stu traced a washer to produce the curves. This is the other motif Stewart is using; so far gusset at base of steering head and on top triple tree...
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Chopit'nrideit... Prof

Bearcx
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Re: Stu's KZ1100 #4... rear end...

Post by Bearcx » Fri Jul 11, 2014 9:24 pm

Why can't you use a stainless acorn nut, Prof? Should be available in any thread form. Just curious....
The brave may not live long, but, the cautious do not live at all.

Prof
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Sat Jul 12, 2014 12:16 am

I have only been able to find stainless in Metric coarse rom my supliers.

If I could get stainless fine thread nuts would be very beneficial.
Chopit'nrideit... Prof

Bearcx
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Re: Stu's KZ1100 #4... rear end...

Post by Bearcx » Sat Jul 12, 2014 12:59 pm

Fair enough.

Reckon i've got Metric fine on my CX, but i think they're chromed.
The brave may not live long, but, the cautious do not live at all.

Bearcx
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Re: Stu's KZ1100 #4... rear end...

Post by Bearcx » Sat Jul 12, 2014 1:12 pm

Looked 'em up, but, no thread size given. Website www.CMSNL.com part no. 903XXXXXXXX

http://www.cmsnl.com/honda-cx500a-1980a ... 309315000/
The brave may not live long, but, the cautious do not live at all.

Prof
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Sat Jul 12, 2014 5:57 pm

Now there's a thought.

If anyone can check their bikes and aftermarket suppliers and find the following chrome acorn nuts in M8x1, M10x1.25 and M12x1.5 would be really beneficial to not only myself, but other builders as well.

Don't know of many aftermarket suppliers I know or who use stainless... most seem to be chromed... which chip easily but better than black or zinc.

I do stock stainless and chrome acorns in UNF & UNC.
Chopit'nrideit... Prof

Bearcx
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Re: Stu's KZ1100 #4... rear end...

Post by Bearcx » Mon Jul 14, 2014 1:42 pm

Grab kits available on Fleabay.....


http://www.ebay.com.au/itm/Stainless-St ... 35be9ba1b6
The brave may not live long, but, the cautious do not live at all.

Prof
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Mon Jul 14, 2014 9:06 pm

Some interesting stuff there. No metric or imperial or fine there though.

Standard threads in metric are M6x1(1mm pitch), M8x1.25 M10x1.5 and M12x1.75

Bike manufacturers often use fine pitches in critical areas such as engine mounting bolts, and shockers

Metric fine sizes are M8x1, M10x1, M10x1.25, M12x1.25, M12x1.5. I have not been able to find these in Stainless. If some one knows of a source, let's know please.

Stainless grades in fasteners are 304 and 316. 316 is surgical grade. 304 is quite good enough quality for bike building. Difference between the two grades is mainly rust resistance... but I've never had any problems with 304.
Chopit'nrideit... Prof

Prof
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Re: Stu's KZ1100 #4... rear end...

Post by Prof » Fri Jun 26, 2015 5:36 pm

I'll have to get some pics up soon of the progress on Stu's chopper.

Some really trick lights have been designed into the rear frame, but fabbing not complete. Clip on seat built and... he finished padding it today.

While I write this (picked up a head cold a couple of days ago, so keeping out of the cold) Stu is up there cutting out mounting brackets for the forwards.

As stated at the beginning, Stu's progress is limited by finance. However he proudly gave up cigs a few months ago and is saving about $35 per week. Aim is to put this towards his chopper. He's been helping me a lot around the place but in the last few weeks has been getting back into 'The Beast'...


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Chopit'nrideit... Prof
Chopit'nrideit... Prof

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