Honda-SOHC

Very nice work in detail there.

Hopefully you'll get the deserved running accuracy in response too.

The TPU material is impressive in final product.

We've (son runs a printer) been trying different product to output and assess. Longer print time by some margin, but patience brings a significantly robust final output in terms of material integration and robustness. I'm very impressed at that strength and malleable characteristic, viable with not really much in any way compromised as to the item it's used for.

Definitely recommend a trial to assess potential yourself.

You can get proprietary repair kit to recover the casting.

Example of https://www.ebay.co.uk/itm/227284064706 that puts a durable insert into a larger bore. Then the bleed nipple runs on those thread for functional use.

"But, no rush, a little later I shall be making carb broth,"

Aha, the gourmand method  chuck a couple of eggs in to boil and save energy, is that Michelin Starred œufs ? 

Solder should be 180c melt, so safe in boiling water. But shows a compromised float though, and may need a re soldering before use.

Thanks for the advice and the info on the core plug, I’ll have a measure and see what I can find.

As for the pod filters, they seem difficult to find any decent set up. I’m sure it’s just a case of measuring for the correct size and jetting accordingly? If not the standard box will be going back on.


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Its commonly given (in mists of time & currently extrapolated) that running less restriction on intake side of carbs gives more fuel demand, then following a path to do that, often to bring something unsatisfactory and more mysterious in effect.

Reality is that it drops the vacuum the carb is subjected to, that causing it to pull less fuel for exactly the same combustion demand, resulting in flat spot bogged response.
Normally, the advice gives larger main jets etc to start, which rarely corrects but usually dumps too much fuel at different ratio that may cover some discrepancy, but just adds to confused interpretation.

I'd start with larger pilot jets, by two steps if available. That will also need bespoke setting of airscrew adjustment to optimise the idle running. This will then mainly correct the critical transition fuelling going toward getting into main jet territory.  These idle circuit have some considerable influence over the fuelling curve, more than is generally acknowledged.  They also have to be thoroughly verified as clean, scrupulously. 

The original ignition is a very good design in my view, and works really well in practice. There's limit in currently available parts that can compromise it though, and advantage available (particularly with this carb setup) in using a good electronic system.
The Boyer system offers much thats desirable, over and above std. Notably it keeps the same dwell (saturation time of coils) for all rpm, which should help here. Also a more easily obtained parity between 1&4 ~ 2&3 cylinder firing discrepancy. 
Also try resistance on both plugs and caps, accompanied by the absolute minimum plug gap that's recommended by Honda for the engine.
That should give a decent baseline setting to then evaluate and consider if it's effective or bring points to think about changing.

As already noted, details in other threads discuss at length.

If not certain of caliper status though, ANY impairment of piston seal and it's ability to function correctly (both in pressure & withdrawing piston) will play havoc with the brake getting anywhere near its potential.

That seal groove must be scrupulously clean to work correctly. If the piston doesn't retract on pressure release from letting brake lever go, it'll always drag, heat the disc, glaze both disc and pad surfaces and never give real bite that's anything convincing in brake terms.

I assemble using silicone grease on that seal (different opinions available  ) that to exclude any incidental water/moisture accumulation from use and storage.  Ultimately this controls the corrosion potential at that site, unlike using brake fluid for assembly.  These caliper have no real weather seal there, unlike many more current caliper design. It's all down to that assembly integrity. 

You can see the effect on a MOT brake tester, car or bike, when calipers are free to work as they should. That's as opposed to example with compromise in piston stiction during use.

Built correctly, it'll brake through storage periods too, compromised though, and it'll largely be ineffective at any use time.

These system have design and potential to function well, but without braking power in significant excess, they'll show any compromise easily.

An interesting read Ted.

From the journalist that was on here as "bike-pusher" I believe. Local to me and referenced Tippets Honda, a long time major dealer for them. Now gone same as many bike dealers.

Disagree with his assessment of CB750 handling being "diabolical" and commonly given from people riding smaller bikes generally (although he seems to have been generally riding bikes for magazine testing) so thought there's wider appreciation of type. Wearing Converse All-stars to ride bikes is not really showing good outlook though, is it.
Poor, worn square rear tyres will make them feel cumbersome. But good profile and ability to manhandle the mass makes for a very different outlook, in my experience.

The carbs, PD, likely to need very detailed cleaning to get them effectively running on target, not just up the sizes on mains  running lean likey to have helped conserve the camshaft wear as low excess fuel doesn't cause dilution of oil to make that happen.