Long Sleeping '79 CBX Restoration

[shiskowd]

I haven't posted for a while but have been picking away at various tasks. On the brakes, I was able to thoroughly clean the calipers and master cylinders (boiler water, ultrasonic cleaner, nylon bushes, caliper hone). The cylinder bores look pretty good, there is some light scoring but nothing that should allow brake fluid to get around - I'll find out soon enough. The calipers honed up smooth, the aluminum is stained some as can be seen in the picture for the rear caliper but shouldn't be a problem. I painted with VHT brake caliper rattle can and baked in a small oven per the paint instructions (200F for 2 hrs). Finish looks good and is very hard. I didn't bother replacing the 'red dot' on each component... Never understood what the purpose was. As I removed the old paint finish with aircraft stripper it was evident that the red was painted first, masked and then the final black paint applied. Maybe I'll paint them on later.

I hope the front master cylinder works out as I want to preserve the original. Not an inexpensive venture with all the parts when you compare to the cost of a complete modern mastery cylinder that will work out of the box. I found a NOS Honda master cylinder rebuild kit on ebay for the front brake, new steel braided lines on order with new caliper pistons and seal kits all around. Considering using DOT5 silicone brake fluid when it all comes together - know this is just a bit contentious , but please share you experiences. I can go either way at this point, the zero paint stripping properties and long service life seem compelling.

Spent hours cleaning up the clutch cover with a dozen different sanding grits. Some further Simichrome polishing to go yet but is turning out nice.

[steve murdoch icoa #5322]

A designated curing oven?
Smart move! I heard about the smelly kitchen for years.

More info on the red dots than probably needed to know.
viewtopic.php?f=50&t=7400

[daves79x]

Speaking from a bit of experience, I would not go with DOT5 fluid. I've converted several complete CBX systems to DOT 5 after doing exactly what you did, and about half of them resulted in swelled rubber components that messed the whole system up. I've had it happen with NOS Honda rubber parts and aftermarket as well. All that said, I converted my original '79 to DOT 5 10 years ago and had zero problems with it. IMHO it's too much of a gamble and too much work to change back if it does not work. Go DOT 4 and be happy.

Dave

[EMS]

I did not want to get involved in this discussion. We had this debate a couple of times before and one determined DOT5 user always turned it into a Life-or-Death subject.
I have worked all my professional life in the chassis/steering/suspension industry with a 2½ year stint in brakes.
Let me share some of the facts:
DOT5 was originally developed by the military to be used for vehicles in storage and reduced use.
DOT5 is silicone based and not hygroscopic, which means it does not absorb or form an emulsion with water like DOT3, DOT4 or DOT5a 9all Glycol based fluids)
That does not mean it does not attract moisture.
When it is being shaken or used carelessly during the filling process, moisture will mix with the brake fluid and remains suspended in it.
It will eventually sink to and accumulate to the lowest point in the system and cause corrosion there. Any brake system will contain moisture to a certain extend.
The suspended moisture forms cushions in the brake fluid which will act as a damper under pressure and will cause a "spongy" feel on the pedal or lever.
This is the reason, brake systems with ABS WILL NOT use DOT5. This is also the reason, no racers will use DOT5.
The ONLY advantage DOT5 has over DOT3,4 and 5a is, that it is not agressive to paint.
And because of the above mentioned moisture in the system, DOT5 should also be changed on an annual basis, just like the other fluids.
You will not find a single DOT5 container in my garage/shop
If you feel, DOT5 provides you with a distinct advantage, you should use it.
One big concern then is, like Dave described, whether DOT5 will be compatible with the rubber and seals in the system.
Also, it is absolutely necessary to completely - and I mean completely and thoroughly - flush and clean the system from any remnants of DOT3,4 or 5a, if it was filled with these fluids before, as they react poorly with DOT5 when mixed and coagulate.

[shiskowd]

A designated curing oven?
Smart move! I heard about the smelly kitchen for years.

More info on the red dots than probably needed to know.
viewtopic.php?f=50&t=7400

My 'curing' oven is an old toaster oven I dug out of my basement that I can barely fit in 2 brake calipers at a time, still better than the flack I'd take using the kitchen oven. Thanks for the link on the red dots.

[shiskowd]

Go DOT 4 and be happy.

OK - I got it. Minimal maintenance advantage and high potential for component problems.

Dave, as always, thanks for your practical guidance and Mike, for your thorough supporting background/history lesson. Much appreciated!

[wyly]

A designated curing oven?
Smart move! I heard about the smelly kitchen for years.

More info on the red dots than probably needed to know.
viewtopic.php?f=50&t=7400

My 'curing' oven is an old toaster oven I dug out of my basement that I can barely fit in 2 brake calipers at a time, still better than the flack I'd take using the kitchen oven. Thanks for the link on the red dots.

great idea, the mrs just bought a fancy new oven and retired the old one to storage...now to be repurposed in my garage

[shiskowd]

Continue to plug away on various aspects of the project

Picked up my crank, head and cylinders from my mechanics shop. Cylinders were bored to fit the 0.5mm oversized pistons, I'll still need to check the ring end gap. He also planed the head 0.006" to get it perfectly flat, lightly ground the valve seats to fit the new valves (valve guides were good) and lightly polished the crankshaft journals after confirming the runout is within spec. I measured (plasti-gauge) the crank and rod bearing clearances again just to be certain with the light polishing - still well under the wear limit and inside the standard oil clearance specs, no need for new bearing shells. Waiting for a few pieces to arrive before I can start reassembling the engine. Also...

- determined the rectifier portion of the regulator box is shot (no surprise), diodes don't pass current in any direction with a multimeter, should check with a load resistor but suspect it's flaky
- prep'd the frame, swingarm and other pieces for media blasting & powder coating (gloss black)
- figured a plan to repair the headlight shell (I'll post pictures at some point)
- re-plated all the carb brackets, engine case bolts/washers, cylinder head stubs with a home-made zinc plating setup. Worked great - here is the 'recipe' I used > http://www.gmh-torana.com.au/forums/top ... /?p=773657
- spent hours cleaning the carburetors including a couple rounds in an ultrasonic cleaner, scrubbing the carb bodies with solvent to remove the tough grime, soaking every brass piece in carb cleaner, cleaning/checking every carb body circuit at least twice (all per Mike Nixon's guide). Also wet sanded and lightly polished the carb tops.

Began the carb assembly process today with the Oldschoolcarbs kit...







Going well until the float valves. I repeatedly attempted to clean the valves such that the little spring loaded nub thing would work freely, each time soaking in carb cleaner then air drying with compressed air. They always moved freely immediately after cleaning but checking them a few days later 3 of the 6 would remain sticky and able to collapse but not retract. Not a good thing to maintain accurate float levels. I gave up trying to remedy and ordered a set of Keihin valves from PJMotorsports (good grief - they're made partially of gold, right?) and will continue when they arrive.

[NobleHops]

For the benefit of the next guy coming to grips with sticky float needles, Sudco and Sirius Consolidated both sell genuine Keihin float needles for something like $6 ea. The seats are almost always reusable. That’s how we handle this.

N.

[wyly]

Thorough work on the carbs, you're a braver man than me I let our mutual mechanical wizard rebuild my 6 pack.

I've advised Fred whose newest Z also has carb issues to take it to Willie to look at. I suspect it may sticking float vales as well but he's more stubborn than me and determined to solve it himself.

[shiskowd]

ah.. the infamous starter clutch...

All the pieces look good - the rollers are polished smooth and uniform, the hub they engage similar. Before I put this back together, is there anything that needs to be done? Thread locker on the 3 bolts, liberal oiling with synthetic engine oil, or should that perhaps be dino oil?

[daves79x]

I encourage you to read the many posts about synthetic oil and CBX starter clutches.

Dave

[shiskowd]

I encourage you to read the many posts about synthetic oil and CBX starter clutches.

Dave

I've read many of the posts and the experiences shared. I'm a big fan of synthetic oil, especially in a heat soaked, air cooled lump like the CBX. I had purchased Rotalla T6 a few months ago when it was on sale and today I picked some GN4 not wanting to have to deal with a slipping starter clutch and having no history on the bike. I'll find a use for the T6 elsewhere.



Having just taken apart my starter clutch and given it a thorough inspection, I can theorize why the seemingly inconsistent synthetic oil issues exist. The starter clutch works because in the instance the starter motor drives clutch, the pressure exerted by the roller on the primary shaft hub exceeds the oil film strength and the hardened steel roller comes in contact with the hub effectively gripping it. The force that the roller applies is dependent on the profile and angle of the surface opposite the hub that the roller moves along. As the clutch gets some years of use (# of starts) that surface, softer than the hardened roller, begins to wear/deform ever so slightly. I could see an ever so slight groove or dent in that surface at the exact place the roller makes contact with the hub. That slight dent would change the force vector of the roller and reduce the pressure the roller would exert on the hub. At some point in the timeline of that piece wearing, the roller may not exert sufficient force to fracture the oil film of synthetic oil (which is much higher than conventional oils) and the clutch would start to slip. Switching to conventional oil solves the problem due to the lower film strength the slightly compromised clutch components can overcome and grip the hub.

Lots of variables in the condition of the starter clutch, even when relatively new and the synthetic oil that is used as the tested film strengths vary a fair amount among brands/viscosities.

Maybe I'm way off base with this but it's enough to convince me to forgo the benefits of the synth oil to ensure my clutch, with unknown mileage and past history, will engage when I'm miles from home.

[shiskowd]

Finally starting to assemble the engine!

Installed the freshly plated cylinder studs with thread sealant in all.



I elected to manage the piston/cylinder installation when the engine cases were still split - seems an easier route than struggling with lowering the cylinders on 6 pistons almost simultaneously. My first CBX assembly - maybe I'm overthinking or missing something...

My mechanic bored each cylinder specific to each piston. The ring end gaps were spot on the two I installed thus far. Lightly oiling the cylinder with conventional motor oil prior to slipping the piston in the bore.

[EMS]

The issues that one may incur are not caused by synthetic oil but by the friction inhibitor additives present in a lot of modern oils.
There are always these tall stories about synthetic oil being more "slippery" than dyno oil and leaking through small gaps.
When you bring up these points to someone who works in the oil industry, they smile at you...