Honda CB750K5 Restoration by Royhall

[royhall]

Probably a screw come loose somewhere and got trapped between rotor and stator. There was a few kitchen and bathroom taps in the sump as well. Amazing eh.

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[Bryanj]

Seen that before and never could figure out what caused it, wont stop it working

[Nurse Julie]

We see it very regularly, doesn't cause any issues with function though.

[Laverdaroo]

I didnt think it would but thanks for the conformation, another thing I dont have to replace......brilliant

[Oddjob]

I didnt think it would but thanks for the conformation, another thing I dont have to replace......brilliant

I just took 2 rotors off 2 old cranks I'm scrapping. Bit rusty but will clean up, if you ever feel like replacing it let me know.

[royhall]

Not too much done this week again but the project is still moving forwards. Had a good look through the parts off both engines with a view to picking the best for the rebuild. As the original engine had the chain break where the gears had milled the casing I thought I would better give that set a very close look at. On inspection the original set appears to be in perfect condition, and that includes all except one bearing so that's the set I will use. The bearing that is pressed into the centre of the casing felt ever so slightly tight in one spot so I will replace that, but the others feel perfect so will all be reused. The cush drive rubbers in the primary sprocket feel firm but compliant so there wont be a need for drilling out rivets to replace them (thank heavens). The kickstart gear feels slightly loose on the shaft but from experience they always do. The one from the spare engine feels exactly the same. The output shaft and bearings are in spot on condition as well. All in all I think that's a result just needing the one bearing, about time I had a bit of luck with this build.

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So whilst things are going well I moved on to the oil pump. It was a bit of a mare getting the screws out but got there in the end without any damage or need for new screws (thanks Mr Impact Wrench). I took the pump completely apart and everything got a really good clean in thinners. The rotors were as new and tested well within spec on the feeler gauges. The only problem was changing the centre seal as it was a bitch to get out (somebody out there has a secret to doing that). Fortunately I managed in the end without any damage and the new seal went straight in no problems. Got it all back together with a new gasket and liberal coatings in clean engine oil. I didn't do the usual packing it with Vaseline as I don't like the idea of deliberately putting petrol into the oil (although I realise that it's the way the pro's do it without any problems). Later in the build I use a different way of priming the pump so will touch on that then.

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[royhall]

A large lump of progress came with the wheels coming back from the builder, Alan at Southport Wheels (which isn't really anywhere near Southport). He has made a really nice job of them. The only part of the original wheels left are the hubs which were polished by Alan (MCTID) so thanks for that. I fitted new bearings before they went for building so they could true the wheels to the bearings. The rims were replaced due to the chromers saying the originals were too far gone in one spot. I think that may have been the bottom of the wheel for the many years the bike was stood still and any water has rested there. Shame really as the rest of the rims are in good nick. The new rims came from Silvers and are DID items but from the far east, but they appear to be a good match for the originals. The stainless spokes were supplied by Southport Wheels with one set straight and one set butted. The wheel builder fitted my new tyres and tubes so that saved me a wrestling match. Tyres are my favourite Avon Road-Rider MK2. That's a very expensive item out of the way, altogether about a £700 investment.

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Other parts are out for work such as:

Vapour blasting with Higgspeed (the two stroke exhaust people). These I am collecting tommorow.
Chroming with Aaron at RestoreMyChrome. This will be ages, always is.
Zinc Plating with Niphos Coatings in Crewe.
Painting with Alex at Thornton Paints near home.

The next project is to try to get all the electrical parts as every single item on mine needs replacing. But that said I have a Boyer Bransden kit on the shelf with the micro coils so I will use that. Handy as my ignition advancer is rusted up solid and the Boyer doesn't need one. I also have a solid state regulator/rectifier spare that I bought for my 750F2 and didn't use. The fuse box silvers have in stock, and I already have a new wiring harness and sub harness for the alternator. Looking at the above I think this will be an easy project as I already have most of it. I will also need a starter solenoid and a horn (mine is rusty and doesn't work).

[Laverda Dave]

Great progress Roy.
I watch with interest re the chrome and the timescales, I think I need to find somebody new as my guy has now stopped chroming due to environmental conditions.

[Johnny4428]

Nice work Roy, interesting to see the progress.

[JamesH]

Very nice progress Roy

[philward]

Alan built my CR750 Rep Borrani (replica) alloy wheels (went to his house in Maghull on outskirts of Liverpool) - great job.
I used DS supplied DID rims on my 500 (I built them up myself) but only been on the bike a year (in heated garage) and signs of rust showing - disappointed really

[K2-K6]

Alan built my CR750 Rep Borrani (replica) alloy wheels (went to his house in Maghull on outskirts of Liverpool) - great job.
I used DS supplied DID rims on my 500 (I built them up myself) but only been on the bike a year (in heated garage) and signs of rust showing - disappointed really

You could try using castor oil on the chrome, lightly coat it and leave a couple of days, then gently buff it (not polish it away) it's highly water repelling and will likely stop any moisture going through porous chrome to pick up on the steel.  Not what you'd expect for a chromed item , but may give you contingency to prevent it increasing.

[philward]

Thanks for the tip, only very light signs which are easily removed but still disappointing for a so called quality rim.

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[royhall]

The project is grinding along at a slow pace as usual. The cases/barrels/head are back from vapour blasting and ready for a really good clean in all the nooks and crannies (what are nooks and crannies?). Once clean I will mask off all the "not to be painted areas" and give them 3 or 4 coats of Simoniz SIMVHT31D and give them a good cook in the oven.

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Looking at that picture I have just noticed what looks like a crack on the top of the upper case. That's going to need some urgent investigation. Maybe if I'm lucky it's just a casting mark.

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EDIT: Had a look at the top casting and its thankfully just a very shallow surface scratch.

I managed to get the original data label off the frame intact before it went for powder coating. A little bit of gentle massaging got it back the correct shape with the holes still good enough to rivet. The rivets I used were slightly larger than the originals due to the holes being opened up slightly. I also took the precaution of using clear silicone behind it. It's not perfect but I am more than happy with it. At some point I may just touch it in a little bit with a fine artists brush, or I may just leave it?

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The only other thing done this week is painting the rear cush drive casting and fitting the bearing whilst it was still warm from the paint cooking, yes I used the same Simoniz silver.

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This afternoon my urgent job is to go through the boxes and figure out where everything is and what new parts I still have to get. This is what a CB750 looks like stripped down along with most of the new parts. That lot doesn't incude the frame and engine castings, nor the painted parts that are out for painting. I really need a much much bigger garage.

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[Johnny4428]

Great work Roy, always good to view your progress.