1972 Honda CB175 Super Sport restoration

[911hillclimber]

Not too sure if anyone is still following this fiasco, but one last quick up-date.

The inlet valves have seals on now same as the exhaust, all parts fit.
The valves are still square to the seats but still gave them a quick lapping, but all looks good. Honda precision.

The kick-start action has been strange since the re-build, the design is not the usual 'ratchet' type that is common where you ratchet the engine to the compression feel and kick down. This engine has a design where you simply stab down getting sometimes 50% drive to the crank (via the clutch).

Irritated by this, I presumed I'd assembled it wrong; there is an odd friction spring fitted, and that is retained in a cast groove in the upper engine case.

Of course, you cant see that or get to it unless you remove the bottom half of the engine case.....so, off with clutches, oil pump and a lot more the case was split to reveal the spring was in fact in the groove...

Back on with the case but the garage went really cold and since we have a lot of snow here and 2 deg above I'm building a balsa rubber powered aeroplane (sea plane actually) in the warmth of the house instead.

Engine block to the machine shop Monday, hope that won't take too long and then all back together.

I'll leave detail reporting now until the engine is back in and running, spanners crossed.

[911hillclimber]

Got it to run today after a huge amount of work and cost, frustration and swearing and all the emotions that come with restoring anything.

hope to fine tune the carbs tomorrow and fix a few irritating snags inc a small oil leak on the top of the engine and s l o w l y trickles down the front of the whole engine....

Big big step forward today.

[Nine One One]

So come on then - what was the cause? What did you do to cure it?

[911hillclimber]

You know, I'm not totally sure.

Rebuilt the engine back up but the bloody thing would not fire, not even 1/2 a fart. This was less than a week ago.

After some help from the Honda boys in the USA it was suggested I was not setting the valves on the TDC/Compression stroke.
This is a parallel twin, so both pistons hit TDC together, but the cam sets to fire on one side, then, 360 deg after the other side.

The Haynes manual I have been using is a bit unclear about setting up the cam to the timing, esp the valve tappets, and essentially, the way you install the cam is on the non compression cycle so the spark fires when the one cylinder is at the exhaust side of the 4 stroke cycle.
So.. I turned the engine over 360 deg more after installing the cam etc and then set the tappets to 2 thou clear, inlet and ex, This should be the firing/compression stroke, then advance the crank another 360 to set the tappets for the other cylinder.

I also changed the coil (waste spark type) as I could barely see the spark at the plugs.
Also, the starter packed up. I could barely get the starter clutch to grip the crank and give a good run of revs on the crank during starting...
So, a second hand clutch arrived today which works perfectly.

I then changed the petrol cock on the small fuel supply container I've used on this and previous bikes to give a fuel flow measured in gallons/second, rather than a trickle/hour.

I recon the most contributing factor was of course the cam timing BUT, when I did my other Honda cb175 I followed the manual and don't remember advancing the cam 360.

he coil and the starter changes have mad a big difference, the sparks are big bold n blue.

What a real slog this has been as all the things I did and have done made the situation worse and started to become depressing. I've done flat 6 engines that srang to life first turn of the key, but this little blighter..well, a challenge of patience and tenacity. A real test.

All is not over yet, have to get it all reliably to work on 2 pots etc and some snags to go yet, but really turned the corner.

And Spring is arriving, soon time to try to ride it (though the wife is making discouraging noises).

[Hugo 356]

Great news - I've missed this thread!

[Nine One One]

You know, I'm not totally sure. And Spring is arriving, soon time to try to ride it (though the wife is making discouraging noises).

Don’t worry that’s just wind!

[911hillclimber]

Ha!
If only..
We are on a bike 'Biker's route' where I live and see a lot of minor and very major spills while out and about, she fears for the 'born-again' biker in me coming a cropper.

Somehow, doing sillier things in my Lola race car seems ok-ish, but a T bone with a bike is a real nightmare.

The Honda should have 20 bhp, at the time quite a punch for a 175. Lambreta's of the same size mustered 7 to 8 bhp.

We shall see. I think she would prefer me to sell and fight another restoration than use it.

[Cortina]

If you are sensible , and ride "defensibly" (ie treat ALL other road users as idiots (not tricky around here)) - you'll be grand - she has nothing to worry about. I still manage about 7000 miles a year on two wheels - but I am still extra careful - esp on the first run out or two of the year (which for me is weather dependent) until I get myself switched on to riding again.
go on ..................... just do it .................

[911hillclimber]

My 2 wheeled nutter days finished for me in 1970 when I nearly went under the engine of a double decker bus on my Lambretta in the winter.
I also came off it 3 times going too fast for my skills and luck and had a car pull out in front of me and T boned the side leaving most of the paint off my Union Jack helmet in the dent in the roof.

You are very pliable when 17, but not so when 68.

Time will tell, I can quickly get to quiet country lanes as I'm on the very edge of a green belt, so that should help while my and her's confidence grows.

Re-started the bike this moring for some carb tuning.

The thing actually fired after 3 secs churning and sprang into life. After easing the choke off over 1 minute the silencers were the same temperature and stayed that was during mt attempts to get the tick over to 1200 rpm.
The tacho was 1500 but it sounded far slower than that to me.

Sounds a bit 'rough' but I'm expecting too much off a 1972 parallel twin I think.

[911hillclimber]

More progress today, and one step back.

Have cold started the bike now 4 times, and each time fires quickly on choke and off choke hot in about 2 mins. Both cylinders are warm together, engine response very sharp, lowest tick over is 1500 indicated, but sounds painfully slow to me.
Lots of tiding up on the bike, chain back on etc but on the last run up I switched the headlamp on and the engine stopped immediately.

Might be to do with the generator loom that has lost all its colour, every wire looks the same 93 of them) so need to sort that tomorrow and hope the headlamp behaves. Have not disturbed the loom anywhere else, and all was well before all this engine nonsense.

Always something.

Also, it sound far better with the air filters on.
Still running too rich, plugs are dry black and sooty but both the same, and one sometimes floods and dumps petrol on the floor from the overflow tube.

[KS]

Don't take too much notice of the plugs at this point - the only way to know the true situation is after a ride. Any engine that is only started up and allowed to idle or run for a short time without load will foul its plugs.

[911hillclimber]

Yes, take your point.
The flooding is a real pain, so that is far more an issue for Saturday.
Have a pair of Chinese knock-off carbs I might change the stock float/needle for nylon and viton tipped needle which could fix it.

[911hillclimber]

A few hours tinkering and snagging today with good effect, but maybe 1/2 a step back.
1
Carb flooding.
The rhs carb has persistently flooded at times so this was job #1 today.
Removed it and found some small cloth fiber strands in the needle/seat area, so flushed that out. While apart tried the plastic float and hooked viton tipped needle from the new Chinese carb to the stock carb and all fitted. Put fuel to the carb, and it flooded!
Back to the old parts and on stripping found a small piece of swarf now at the carb needle seat...must be from when I modified the petrol reservoir, so, cleaned that all again...
Replaced the stock parts and no flooding.
Back on the engine and fingers crossed.
2
Ignition key
Put it all back on so I could run the engine (to check the carb etc).
Bloody thing fully functions, even the headlamp/side etc all work.....Will still fit the new one when it arrives next week, and check the key with the seat tumblers.
3
Brake light stopped working I found during the above light test, so with meters checked all that, changed nothing and it works! Must have been the green wire from the switch (new) to the loom as I pulled it and re-instated.
Is this bike spooked?
4
Started the engine to check the carb. All's well, not a drop of fuel.

Made the mistake of tinkering with the carbs while it was running. Still grey smoke from both and after my diligent fine tuning, the LHS is a little cooler than the RHS.
Got the tick over to a reliable 1500 indicated, but it is not happy. Should be smoother I feel.
The LHS (7/8 of the RHS heat) tick over adjuster screw has no effect, it is screwed out and the piston is on the floor of the carb, outer cable 3 mm loose so not holding it off.
RHS is almost the same so there is nothing more mechanically to drop the tick over.

Still a lot of water drops from both silencer ends and also the engine cylinder vent tube. Condensation if you like.
5
Head stud that was weeping oil now doesn't, but the same one on the other side now does!
Is this bike spooked??

Going to leave it alone now until the ign switch arrives.

[Nine One One]

Next project for you, and if we can have some time lapse video recording as well - brilliant!

https://www.hagerty.co.uk/videos/redlin ... ews_Weekly

[911hillclimber]

You are lucky to get pictures from me!

This is good too:

https://youtu.be/G87O15mHBas