750 K2 Strip & Rebuild - help please

[Trigger]

Top engine breather to atmosphere, Oil tank overflow to atmosphere and there is a smaller diameter pipe that comes off the oil tank to the rear crank case  on a K2

[Lobo]

Cheers Trig, wildo

In hindsight I mistakingly mistook the above hose as the large long hose off the cylinder head breather; whereas it’s actually depicting the smaller dia short hose returning separated oil from the tank breather chamber to the rear crankcase.

Doh… & ta.

[Lobo]

Am fitting a Boyer Electronic Ignition to the CB750…
Q if the ignition / kill switches are left ON (engine not running) can the coils burn out, or does the Boyer automatically cut power to the coils after a short time?

Rebuild progressing nicely… slightly disappointed at times to unwrap genuine Honda parts to find a colour change etc. (eg carb rubber bands on this occasion)

 (damned iPad for rotating the pics - must do better 🙁)

[Bryanj]

No the boyer is not that clever, and leaving it on can do it in as well

[Johnny4428]

Nice work Lobo. That is progressing nicely.

[Lobo]

Cheers Johnny; truly on the home straight now.

[Lobo]

This build is just taking so long, things that I earmarked an hour for take a bloody day. Something to do with being bloody anal I guess…

Couldn’t easily find chromed bolts for the indicators / rear wheel stopper bolts, and so had a go at polishing SS ones. Amazed at how nicely they’ve turned out.
Q - will this finish stand the test of time or is it not indeed a satis replacement form chrome?

Bought some thin-walled clear heat shrink tubing today (Jaycar) and put it over the brake / clutch levers / used boiling water. Really pleased with the result.

Applied Piki’s (thanks!) DOT 5 Silicon label to the Master Cylinder - again, very happy.  The M/C btw has been powder coated and had all new internals + (obviously) DOT 5 Silicon. Bled easily, no leaks …. front brake signed off.

Hopefully now only a few days from start up.

Edit… I think the upper brake hose should go down through the bridge top ‘triangle’, but routing it this way resulted in a 20-30 deg twist needed to seat the hose at either end. It just felt wrong, and so the hose retains its original routing down the RHS of the bridge toward the pressure switch unit.

[Oddjob]

The stainless bolt will outlast any chrome bolt. No more little pitting appearing on the top of the bolt. I've gone this way as well, although I did fit a washer under the head to stop it gouging into the chrome of the body, which on closer inspection you have also done, stainless as well?

[Lobo]

Yep, always using washers where possible, and indeed SS. Good to know that the shine will keep. Cheers Ken.

[Lobo]

Putting in the battery earth today, necessitating sanding away the powder coat at the outside frame engine mount when I realised the engine itself is not properly grounded as I didn’t bare the frame where it butts up against the gear case. Doh.

My plan now is to bare the forward LH outside mount; that bolt fastens directly to the forward crankcase. Any comments before I take away paint - better ideas?

Quite glad I didn’t spin the starter motor in this state…

Ta.

[Oddjob]

Personally I'd remove the upper rear hanger bolt, remove the spacer, then remove the paint from inside the frame at that point, fit the battery earth strap between the spacer and the frame even if that means shortening the spacer by a couple of mm. I wouldn't do the front hanger as it get's all sorts of stuff thrown at that part of the frame and you don't want to encourage rust.

[Lobo]

Ah, cheers Ken, but it ain’t that simple as there’s no such spacer on the CB750 mounts.
I’ve gone with my plan A, and using a small Dremel 220 disc carefully removed only paint behind the bolt head … and used a spring washer there plus carbon conductive grease. It’s all invisible.

Tbh, I hadn’t thought of the crud / corrosion angle, but am now actually happier as this is a very visible and accessible area should rust ever start - which can only be from washing as the bike won’t be ridden in the wet.

I now rather pleased that the hidden inside of the rear frame has completely maintained its 2 pack integrity…. ‘serendipitous’ comes to mind 😀

[Lobo]

A double win today…
(1) inserted a battery, and presto, ALL electrics worked immediately. Was pleasantly surprised by front brake pressure switch, as for some forgotten reason I was expecting trouble there.
(2) injected each tappet hole with 150cc of 20W50 Mineral, and the rest into the oil tank. Bunged 5cc down each plug hole, and foot cranked the motor a few times (plugs out). Then, via the starter cranked it, and after about 3*10 second engagements… bingo. Oil pressure light out… and back on at cessation. Bloody pleased… a good day.

Sat / Sun will be the exhausts back on, and then first start attempts.

[McCabe-Thiele (Ted)]

Ah, cheers Ken, but it ain’t that simple as there’s no such spacer on the CB750 mounts.
I’ve gone with my plan A, and using a small Dremel 220 disc carefully removed only paint behind the bolt head … and used a spring washer there plus carbon conductive grease. It’s all invisible.

Tbh, I hadn’t thought of the crud / corrosion angle, but am now actually happier as this is a very visible and accessible area should rust ever start - which can only be from washing as the bike won’t be ridden in the wet.

I now rather pleased that the hidden inside of the rear frame has completely maintained its 2 pack integrity…. ‘serendipitous’ comes to mind 😀

Have you ever tried the waterless cleaner sprays? - they are surprisingly effective on cars so should be good on bikes as well.

Not to mention the new generation of waterless coolants for water cooled engines.

[Lobo]

No Ted… I hadn’t even considered it! My greatest concern would be dragging any small grit particles across the paintwork - how does this ‘system’ avoid such damage?

And what the hell is waterless coolant 😂? Intrigued…