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Discussion Starter #1
I thought I'd better start a new thread, both to avoid confusion, and to motivate me to get on with it.

As I mentioned in another thread, I have accumulated nearly enough spare 175 bits to put another bike together. And as I'm starting from a pile of unrelated parts, rather than desecrating an existing bike, I have no qualms about building something that may indeed turn out to be my very own 'brat' bike !

What I think I'm aiming to do is to convert my heap of bits into something resembling an SL175 !

sl1752.JPG

I just needed to source a few of the parts that I'm missing, and can't fabricate myself. So, yesterday, a box arrived containing a CB175 swing arm, CB200 swing arm pivot bolt, CB175 rear footpeg / exhaust mount brackets and chain adjusters.

The swing arm bushes were rusted solid, completely seized, so first task was to extract them, using a piece of M10 stud, some M10 nuts, a 1/2" drive 13mm socket and a 19mm socket. Good soak in GT85 ( like WD40 but smells nicer ), and out they came, after using quite a bit of force, some creaking and cracking noises as the rust lost its hold.

Rust removed and bushes bores cleaned up, all fits together nice and freely now, most satisfying.

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Excellent idea Richard - the SL175 has a place in my heart as it was my first brand new bike when I was 15. Looking forward to watching your project come together.
 

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Cheers to you for not chopping up a survivor! Looking forward to the updates- best of luck with the build.
 

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Cheers to you for not chopping up a survivor! Looking forward to the updates- best of luck with the build.
Chopping up bikes is not in Richard's DNA... he is a staunch supporter of keeping vintage bikes complete and unmolested - and kudos to him for it
 

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Discussion Starter #6
Dogs barking, courier in front porch, CD250u fork legs arrived ! :p

I have a CB200 top yoke, and a CB175K4 bottom yoke already, so top end sorted, it's how the wheel and front brake will fit is the next puzzle. However, Simo has already done this conversion, so it is clearly feasible.

I hope ….
 

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Discussion Starter #7
Down to the garage this afternoon, after watching the MotoGP qualifying sessions.

The CD250u fork stanchions are in good condition, no rust or pitting, chromed all the way up, unlike the 175 forks. Seals are weeping, but I have a new set to go in. The forks fit into my yokes nicely, and protrude 40mm through the top yoke before contact with the handlebars, so that should take care of the extra length OK.

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Front wheel fits nicely, and it looks as though the stock spacer will be the correct length. Only place I could find one was in the USA, so ordered placed at pathetic UKP to USD exchange rate. I have a relative with a large machine shop, but I don't like to impose on him, working hard to earn a living and keeping shop going.

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Looks as though someone at Honda had standardisation in mind, even the mudguard (fender ;)) mounts align correctly.

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Top brake caliper mounting point will work out well as a mount for the brake plate torque arm, just needs a small spacer to get it to align. Fork bottoms will get a coat of silver paint whilst apart for new seals, and I'll probably cut off the redundant parts of the caliper mount.

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It occurs to me that these forks might be an option for a CB200 owner wishing to change the mechanical caliper to a hydraulic one.

I measured the 250 and 175 fork bottoms, to check that spacer would be correct size.

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250 fork bottoms, 33.09 + 35.99 = 69.08mm

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175 bottoms both the same. 34.13 x 2 = 68.26mm

I think I can safely put the 0.82mm difference down to measuring error …….
 

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Discussion Starter #8
I probably won't use the fender mounts on the fork legs, although I might make a fork brace, fitted to them. Odd that the real SL175 doesn't have a fork brace as standard.

I was trying to figure out how to mount an off road fender to the bottom yoke, and the only thing I could think of would be a crude bracket bolted to the lower pinch bolts. I assumed that the real SL175 would have a special bottom yoke with tapped mounting holes for the fender.

Imagine my surprise when checking the parts fiches. Honda just used 'a crude bracket bolted to the lower pinch bolts' ! Looks easy enough to copy something usable, just need to source a generic fibreglass fender.

bracket.JPG front fender.JPG

Here's some pics of PO's modifications / 'repairs' to the frame I'm going to use. The side stand bracket isn't actually such a bad idea, as this bike won't have a centre stand or CB style exhaust pipes.

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I'm guessing you've already thought of this, but I suspect the original fender has some supporting hardware built into it that the bolts that hold the bracket in place pass through. Chances are it's only a couple of thin metal plate strips to spread the load, but yeah, it's pretty rudimentary.

Contrast that to the belt-and-braces set up on the SL350 K0, which has a steel guard, with a steel frame. No fork brace, but with that much steel up front, it doesn't really need it. I guess Honda learned by the time they started putting out the small capacity machines that as well as doing pretty much the same job, fibreglass is both considerably lighter and cheaper than steel . . .
 

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Discussion Starter #10
Quick dry build today, sorting out which little odds and ends I need to source or make.

Front brake torque arm found in my box of bits, not a 175 part, but does the job, attached to remaining caliper mount using a bolt and spacer, not shown in this photo taken this morning, torque arm at better angle now.

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Can you find an SL tank for it? That would really make it look the part - and paint the frame silver, of course
 

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Discussion Starter #12
Agree about the SL tank, but I'm trying to use up as many as possible of the parts that I've got already. I'll probably just paint that K4 tank in an SL colour scheme, red of course :grin:

I do intend to paint the frame silver / aluminium, to mimic the SL frame, paint arrived the other day as it happens.
 

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Discussion Starter #14
The frame will need a hoop at the back, if I'm to mimic the SL rear fender setup.

However, I'm not going to butcher the frame with an angle grinder and chicken poo welds, as is so common. The frame has mounting points for the standard seat and indicator mounting bridge, so I plan to get an aftermarket frame loop, and weld brackets to that, so that it will bolt in place.

20190813_102021.jpg sl1757.JPG
 

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Discussion Starter #15
Agree about the SL tank, but I'm trying to use up as many as possible of the parts that I've got already.
Must stop looking at online sales sites.:mad:

SL 175 tank on the way …….

sltank.JPG
 

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^^^there you go - now, with the adapted rear frame loop and the SL tank, basically all it will be missing is the double-downtube frame
 

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Discussion Starter #17
Don't worry, I have looked long and hard at some SL frames on a certain sales site, but I had to tell myself that this was defeating the object, which was reusing my existing parts pile.

That said, the SL frame is a work of art, much nicer than the CD/CB/CL frame.
 

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Discussion Starter #18 (Edited)
Trial fit of the tank revealed a couple of problems.

The front mounts on the CB frame are too far forward, and the CB frame is too 'fat' at the rear of the spine section, so the saddle of the tank is a very tight fit at that point, doesn't quite sit down far enough to meet the rear mounting point.

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So, I'll drill straight through the frame and fit a new mounting bar, tack welds at either side should hold it.

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And do some gentle panel beating under the fuel tank :twisted:

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EDIT A few blows with the hammer, and it drops into position nicely. :grin:
 

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Discussion Starter #20
Badges removed, both in excellent condition after a good scrub with soap and nail brush.

Templates made of tank graphics, then on with the industrial strength paint stripper, down to bare metal in moments.

Followed by a bath in phosphoric acid rust remover. Rain stopped play.

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Ordered a bit of 10mm diameter mild steel bar to make the new front tank mounts.
 
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