Honda-SOHC

As above, possibly available to replace easily.

Generally though, they work well with parts in good condition.

Obviously a new lifter plate needed, set of EBC plates is good start point too. F2 model (the original not later re-use of name) from last SOHC 750 build used stronger clutch springs that can be substitute for softer original.  They give harder bite to original clutch pack but with stronger leaver pull.

Assembly of lift plate, tighten carefully with 1/4 drive socket set, pulling each one down equally as you pull plate tight in parallel to avoid snapping.
They "snag" if you've not got the alignment right as the assembly closes, you can feel this with small ratchet leverage as it bottoms out early STOP there and back out the bolts to check you've got it aligned properly. Don't keep winding them in and hoping. You may have to wriggle the plate you're pulling through from the rear by tightening to ensure it sts into engagement on its drive splines at the back of clutch pack, and not nose to nose on those spline.

Sounds more complex than it is, but taking time and care with carefully observation avoid damage. They're not big loads as you tighten and should bring suspicion if there's much in the way of resistance doing this.

A few years back, BoShield T9 was popular in the marine world for such protection.  I've been away from marine stuff since 2017 so don't know if it's still popular.

Sweet hayzoos, that stuff is expensive, especially through chandlery stores.

From it's MSDS sheet disclosure though, light oil of petroleum origin 25~50% Naptha (lighter fluid, for helping dispersion) 25%, white mineral oil 25% plus some propellant to get it out of the tin.

Literally, money for old oil 

Most of these product are the same in operation, light oil dispersed by carrier liquid that evaporates eventually and after creeping into cracks etc. To then leave a light oil coating on the treated surface.

Hi we have a customer with a 1976 CB750 the clutch pressure plate the one with 4 springs has a crack in it can we use a clutch from a new Honda CB750 that will fit straight in with more springs.

Many Thanks Sheps

Unless you've got something there, available and definitely fits, then I dont know of something with that replacement potential.

The early CB 750 is fairly unique in tbat design, with not much in the way of compatability from later type designs.

As noted above, the cracked spring plate on these comes from incorrectly assembled components, ultimately tightened down on springs with some internal misalignment.  Durability when correctly assembled isn't usually a problem with them.

So if I get 5-10 miles on it then hit the kill switch and get the plugs out

The miles should clean out combustion, allow it to reach full running temperature, and clean any fouling from the plug surfaces to avoid giving false perception after cold start etc.

Kill switch routine is ordinarily when you are checking fully loaded running at big throttle opening and hard on torque demand. That entails pulling it hard with substantial throttle, running up fully on main jet at maximum demand conditions to asses the mixture under those circumstances. Valid for those reasons as you want to suspend running right at that maximum demand to get the most accurate picture of the prevailing combustion conditions.

  It's not for this scenario of general setup and checking if the very low speed system of jetting is accurate.  A simple run out to get it fully warmed etc is just fine to build a picture.

I don't routinely replace plug washers, always use a light smear of copper type lubrication on threads, and lightly tighten. Never have any leaks or compromised threads in practice.

Quote from: DomP on July 21, 2024, 12:17:42 PM

All back on and set to 1.5 turns out, no more hanging idle but smells very rich.  Could it just be that I need to get out on it and get some miles on it now?

Aside from it smelling rich are there other signs such as an overly cold exhaust - I assume you have tried opening up the air screws a tad.

I found a decent run often helps as you get the whole system up to temperature plus when riding you will burn up the fuel through the rev range moving onto the main needle jets.

Agree with this.

Would go further in this direction to evaluate what range you're actually operating in. Turn the airscrews out to 2 3/4 for a functionality check in establishing IF there's enough range of adjustment to correct what exists currently.

If they get to 3 turns out, and without correcting mixture adequately, likey that the idle jets themselves are flowing too much fuel. This is effectively what an "engine check light" on fuel injection is doing, telling you it's reached the maximum allowed in programmed adjustment but not successful in fully corrected output.

MOST of these carburettor would have the adjustment range of screw within 1 ~ 3 turns out, past those positions would indicate the fuel jet is too large or too small for application.  That could be partly blocked, enlarged through cleaning, or the wrong size simply installed.

Going for maximum outwards is not to run it like that but to answer the question of IF it can be corrected within design parameters.  Try it to find out. It could be that one size smaller jet is suitable in this case.

Before this though, are you confident of the air filter fitted ? That could also significantly skew results here.

I wouldn't worry too much about the smoke as they're doing quite a job down here when they set those there "electrical" buses on fire, 3 at least in public, more apparently in storage 

They make a heluva smoke screen, much worse than a herd of two strokes 

Some of the earlier taps look like they weren't bespoke, more off the shelf type arrangement tgat didn't take account of other items close by, not a huge amount of room around there anyway.

Original fuel pipes had quite thick wall, making them resistant to kicking like this too.

Wouldn't hurt to use length change in looping lower and back up again to ease pathway either.

K type 750 would usually run for about 3 miles with fuel off just on float bowls as I often turned mine off on way home to habitually leave the carbs more or less empty when not in use.

If you find anything significant, then also include rear sprocket for concentricity to eliminate that part.

Sometimes you can here quite clearly when someone pulls away from a bike meet or similar a pulsing noise as they rotate the wheel.

If the chain is definitely bad, then not much option but to replace.

If it did in any way appear to be corrosion linked (chain pins etc) then trying a EP gear oil application could be effective. GL5 rated is very good on chains and has not much smell like older oils of this type are characteristic in pong.

Hopefully detailed inspection will confirm if there's anything to be acted apon.