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My CB/CL/SL 175 resurrection project

28K views 217 replies 25 participants last post by  rodcarlile 
#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 !

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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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#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 …….
 
#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.

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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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#9 ·
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 . . .
 
#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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#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.
 
#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.

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#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:
 
#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.
 
#22 ·
Hi Simo !

Yes, the exhaust is exercising me somewhat.

My plan is that is going to be a long term project, keep me out of mischief for a few months, so exhaust is on the back burner at the moment.

In an ideal world, an SL175 system would go on. However, these are rare and expensive, and I doubt that it would fit the CB frame without extensive mods, so it'll probably simpler to build ( or get built ) a custom system. Also, for an off road bike, it seems mad to run the pipes under the frame. Despite the stock bash plates, used pipes I've seen on line are often well dented.

I don't want to go for a high level CL type system. Pipes will be in matt black heatproof paint on mild steel, not chromed or stainless tube. So, bend some 38mm tube to make a 2:1 system similar to the SL, with an silencer can in the SL position is one possibility.

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Or, perhaps simpler but heavier, something like the SL350 system, with individual exhaust pipes and a can on either side. That could be achieved using the stock CB down pipes, extended with 38mm tube with a 30 degree mandrel bend to flip the end of the pipes up, into silencers mounted in the SL350 style.

For silencer(s), I'm looking at Triumph Street Triple 675 cans. These are available very cheaply on Ebay, many owners ditching them in favour of noisy straight through 'race' exhausts. No catalytic converter in them, I won't get caught like that again.

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( I fitted a Triumph Scrambler can to my CL175, couldn't work out why it was getting too hot to touch, until it dawned on me that the internal catalyst was struggling to cope with rich carburetted exhaust gases ! ) The Street and Speed Triples have the catalyst in pipework closer to the engine.
 
#23 ·
CD250u forks stripped and cleaned.

They came apart really easily, didn't need the electric impact wrench, fork bottom allen bolts came out without a problem. Similarly, no internal circlip retaining the fork seals, just a simple wire ring, easily fished out using a small screwdriver.

Nothing prepared me for the mess though. I just assumed that ancient leaking forks would be almost empty, instead of which floods of filthy black oil poured out. And after the oil came out, fork internals were still filthy. No real signs of wear, so this muck must get past the seals over the years.

Fork top bolts had been butchered, apparently by a chimp using a pipe wrench. Luckily, I found some marginally better ones in my box of bits. Same ones used on CB200, CB400/4 etc.

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Fork bottoms cleaned and painted, using Metal Protekt aluminium coloured direct to metal paint. I'd intended to use this on the frame parts, but I think it is a bit too bright, Hammerite silver may be more suitable.

Ready to reassemble now, got the fork seals, just need to get some fork oil, 150ml each side, probably go for 10w.

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#26 ·
I got the forks reassembled with new seals today, after a further wash with solvent to get the dregs of the black mess out of them. Remembered to put some sealant on the threads of the allen bolt at the bottom of the fork leg, to back up the existing copper washer.

I made up a fork seal driver from a length of 35mm OD stainless steel tube, and a section of 35mm PVC waste pipe, opened up with a lengthwise saw cut, so that it could be slipped over the outside of the steel tube, to make the OD big enough to bear on the outer edge of the lubricated fork seal. Worked a treat, used like a slide hammer.

Primed tanks now painted Honda Milano red, curing nicely in todays sunshine.

Some more parts of the jigsaw arrived today, an aftermarked Honda CRF front fender, and a secondhand rear fender from an SL175.

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Front fender looks like it will fit nicely, fits neatly under the bottom yoke, just need to make up a bracket like the original SL part. Rear fender fits snuggly between the rear frame rails, I will just have to fabricate a small matching section to fill the gap under the seat, between the integral fender in the frame, and the new part. I can also now get an idea of how a rear hoop can be fitted, to emulate the SL frame. I'll do a mockup build in the next few days, post a pic then.
 
#27 ·
Mock up, as promised.

I was going to fit an aftermarket 'brat' seat, but it looked crap and the build quality was appalling. So I've decided to use the original CB175 K4 seat, which I think works quite well with the SL tank and rear fender. Two holes with captive nuts in the SL fender line up with the two rearmost holes in the CB frame, accident or design ?

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I've made up a small mild steel section to fill the gap between the SL fender and the CB frame, and tack welded this to the SL fender. Will weld this up a bit better then clean and paint the whole assembly. I've also finalised the position of the tank on the frame, need to sort out the mounts now. Also make up a mount for the front fender. Get the fuel tank masked up ready for the white paint and stripe.

Crappy 'brat' seat.

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