1972 Honda CB175 Super Sport restoration

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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

A few more hours in the garage on the bike progressed things a little.
I think after this post I'll slow reports down until a major milestone is reached.

Missing on the bike was the second pair of exhaust sleeve halves, and as these are also hyper rare (at a reasonable price) I made some from metals I had around me.

That job done the front wheel went in and after a few tries finally sorted the tls lever travel out so I have max leverage at just before contact of the shoes.
Other parts should arrive tomorrow to finish off the mech parts of this rebuild tomorrow, then it has to be the electrics...

The proportions of these little Honda twins is just so right.

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neilbardsley
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Re: 1972 Honda CB175 Super Sport restoration

Post by neilbardsley »

Looking good Graham. You might struggle to find a nice day for a test drive

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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Yes...
I thought this bike would be a quickie, but it's dragging on a touch, so never gave the weather or time of year much thought.
Always found Project Planning a bit of a bore at work, and in retirement too!

I was hoping to be done by end of Sept, now end of October, but... :roll:
73T 911 Coupe, road/hillclimber 3.2L
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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Wires.
Hate the bloody things esp when the new loom does not follow the original colour codes, so Yellow/red = yellow etc and some wires are terminated with a female and the incoming wire is also female.
It is all done inside the headlamp cowl so very cramped and hard to see which wire comes from where.

anyway, might have almost cracked it, just have 3 wires with no obvious place to go.
Need to fit a battery and a small fuse and actually run the circuits 'hot'.

Brake arm, centre stand springs on (all OEM) and the OEM handle bar grips too, the 'anti-vibration' type to help prevent your hands going numb when riding this vibration machine!

Front brake all done up and at least some steps forward even if slow and single digit.

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73T 911 Coupe, road/hillclimber 3.2L
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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Pc is currently in trouble, so no pics.

Have spent hours sorting the simple electrics on this bike, but it has been awkward and confusing in equal measure, but really nearly there.
I still have 3 wires with nowhere to go and I think they will be covered (male terminals) and tucked away.
The indicators took some time but with a new relay and a special devoted earth they are super bright.
Gearbox Neutral position and clock light done, rear brake light and several other functions are all done using many new parts and terminals.
Blue wires had faded to grey, one blue had gone purple and several whites had lost their red stripes, many connectors on the new loom had the opposite orientation so terminals and special water proof insulation sleeves had to be soldered on and heat shrink sleeves in many places.

Also, being colour blind to red and green does not help, I was banned from doing electrics as an apprentice way back for the same reason.

Very hard to make it all look neat, when you lift the seat you see the electrics in total, and still looks like a nest of angry adders.

To do are the haeadlamps functions and lastly the electric starter which had a duff original solenoid, clicked but would not switch the big current solenoid.
Good secondhand one arrived yesterday for £27. fingers crossed for that!

Really close to petrol and start-up.
My last chance ran on one carb, then the other and took some very fine balancing to get the twin carbs to pull and run hot, but when done these twins show their true character.

Just might get this one done by end October and that dry sunny day I've ordered for the first ride round the cul de sac. :)
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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Bike all electrically fully functional so time for oil, battery and petrol.

This could be tricky as carbs and sparks are not my strongest skill.

Not far from being finished! :( :shock:

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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

One carb leaks from the bottom bowl gasket, so need to replace the rubber seal that has been compressed for 48 years...

Will do both carbs, kit on order.

However, it runs. Lovely Honda Twin rumble, vibrations everywhere (they are all like that).

Some tuning to do tomorrow, but a great kick-off to the last match.
73T 911 Coupe, road/hillclimber 3.2L
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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Slightly premature rejoicing I'm afraid.
Just like with the gold cb, the carbs and ignition are playing games, but I think I have it sussed.

Carb gasket kit arrives tomorrow and a new coil pack soon and we should be sorted. Me and carbs and sparks are not happy together.
The joker in the pack is a neutral switch/circuit that was intermittent, and nothing starts if that circuit is out. Fixed that with a cable tie to keep the socket halves together.

Seem to have a leaking front strut but not sure from where but suspect the new seal I fitted.
Pain to take it apart, but no big deal.
Tacho is fluctuating suddenly, new cable etc and worked well for a while, could be in need of another, but worth cracking it open to see if I can find a fix (I have a spare to test the cable which is incorrect for the bike.

Just a short list of snags (so far) :)

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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

t's getting irritating.
Fresh float gaskets, 21mm float heights, still a dribble every now and then from the overflows.
Brand new coil.

Got it started ok, very hard to get a reliable tick-over, according to the tach best I can get is 1900 or so before it stops.
Air screws do noting, so presume the tacho is reading accurately enough.

Thr rh side that was running cold now runs hot and the left is now luke warm, about 32 deg C, the temperature difference is just touchable at the exhaust tip on the rh side, easy/cold touch on the lh side.
This is exactly how my gold cb was, the hot/cold sides would alternate not during a run on the bench, but between cold starts sometimes.
Bowls are full due to occasional weeping from the overflows.

So, just how do I get these to balance? Any ideas please?
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Cortina
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Re: 1972 Honda CB175 Super Sport restoration

Post by Cortina »

Part of me says stay quiet , part of me wants to sort.

What you have written does not make a lot of sense (to me) - lots of different unrelated issues. I suggest eating elephant in small bites.

Let's start at the top.
1. Get the float heights correct - double check what you have , they need to be essentially correct and the same. If these are correct AND the needle valves are working correctly , you do NOT get fuel leaks (overflows / dribbles). Sort this one now - find the problem , fix it ,then move on to next issue.

(sorry if I sound like annoyed school teacher)

I have no idea what running hot and cold means - is this code for it's running on one cylinder ??

more later when you tell me that one is sorted

PS I have no idea what you need a rev counter for at this stage ?
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Kneeslider
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Re: 1972 Honda CB175 Super Sport restoration

Post by Kneeslider »

^^This^^

Old Japanese bikes are notorious for dribbling float valves. Give these a very thorough looking at. If they have any discernable wear rings on the needles they will give trouble. If you are very lucky, then they might lap in, but usually new ones are needed. Also could be due to crud in the fuel tank getting between the needle and seat. This problem seems to me to be due to Keihin specifying small floats that aren't quite up to the job of seating the needles. Mikuni are usually better. I'm assuming that, being a Honda, its got a pair of Keihins?
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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Thanks for helping me:
The floats are factory spec @21mm measured with the float hanging down like a pendulum and just kissing the needle, not compressing the needle crush spring. 21mm is measured from the base of the carb body and the float diameter.
I think the needle cone is metal to metal as nowhere is a viton seal mentioned in books etc. Easy to strip and look harder.

Carbs are Keihins, #644A, with factory jets etc all rigorously cleaned and poked through.
Carb gaskets are fresh today Honda parts.
They do not flood all the time, never when running of course.

Hot and cold refer to the relative temperatures of the down pipes of this twin.
One pipe will be untouchable, (hot) and the other at the same time of running around 35 deg C (cold)
Obviously both should be the same, ie both hot, but the hot and cold switch sometimes from side to side when you start the engine from cold. This is random and follows no pattern.

After running for 3 to 4 mins the hot side plug is dry black sooty, the cold far less so.

I have never had one cylinder hot to the touch and the other ambient (ie not firing at all), there is some % of combustion going on.

Tomorrow I will check all I've done.
ignition timing, points gap, all the carbs again.
I am doing all this snagging using a petrol pot not the tank so all is clean there.

The rev counter is used in the tuning instructions to ensure the pilot adjustment is correct.

The factory instructions are:
1
Start and warm the engine after synchronising the slide movements to be equal when using the twist grip and the pilot air ratio screw 1.15 turns out from tight.
2
Warm the engine and ease the twist grip down to 1200 rpm 'as indicated by the tacho'.
The pilot circuit is over-ridden after 1300 rpm.
3
screw in the tick over slide screws until 1300 rpm is held and incrementally drop the tick over on both carbs to 1200/1100 rpm tick over shown on the tacho.
4
screw the air ratio screws until the engine reaches it highest rpm. When max tickover is found the carbs are balanced and the tick over then adjusted evenly down to 1200 rpm.

This suggests a rise of about 1000 rpm can be expected adjusting the air ratio screws.
There are no other adjustments to be made on these carbs, air ratio at 1200 and tick over speed.
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911hillclimber
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Think I've got it today.
Stripped the carbs for the 8th time, cleaned and cleaned again, poked all the holes etc and re-assembled.

It started just like that, instant on the electric starter and I warmed it up.
Had the usual hot side/cold side and it almost switch over sides during some tweaking, BUT I seem to have found a sweet spot.

The tick over is close to a Harley though the tacho says 1800 sounds more like 3 rpm to me.
The pilot screw seems close to redundant but has with some combination of throttle slide adjustment seem to have bought the engine to balance, the silencer temps are really close.

Boyed by that, the next step is to fit the air filters and see if things are all ok after and re-tweak. These little bike can be sensitive I've read to the choking effect of the cleaners, but I hope my custom foam ones will win through.

Number plate arrives tomorrow, seat on and IT IS FINISHED. :shock:
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Kneeslider
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Re: 1972 Honda CB175 Super Sport restoration

Post by Kneeslider »

Yay!!

Just a thought, but did the carbs only overflow when you had a higher 'head' of fuel from your dummy tank than you could ever have if the normal tank was fitted? Quite often the float bowls will have been pulled out of flat by the screws holding them on, I guess that could account for the drips too?

I'm super impressed at how you have managed to crack on with this one. All my things are still all broken in bits. The 356 engine is all over the garage, and some of it is at PRS. The Velocette is progressing really slowly and frustrating, as a lot of the new parts have to go back because they are a long way from fitting. The Mondial is in a mate's hangar in Oxfordshire due to too many other things in bits, and we have just about to go into level2 lockdown so it looks like I'm not going to be able to visit it any time soon, which is a shame, because it is just about a runner at last.
'65 356 SC
'91 Ducati 750/900ss mongrel
1963 Velocette Viper (mostly) with '39 KSS OHC engine
'05 997 C2
1954 FB Mondial 200 Extra Lusso
911hillclimber
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Posts: 19025
Joined: Mon Mar 10, 2008 6:26 pm
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Re: 1972 Honda CB175 Super Sport restoration

Post by 911hillclimber »

Thanks for your kind thoughts.
I think this has taken far too long esp now the weather has broken.

The petrol vessel is above the tank height but not by too much, maybe just 50mm, I expect to final fit the tank soon and run the bike several times to make sure all is well.
The petcock is new ( and expensive) so will flow well, as well as the temporary set-up, so I hope all will be good!

Have a small issue with the left hand air filter connection to the carb, trying to find a very rare part nla, but might have struck lucky.

It does not show on this project the hours spent on the internet trying to find parts and information, but there is a very ddk esc forum in the USA that is global in its reach and has been a god send.

Final task will be to add up the costs..... :lol:
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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