CB750 Barn find project - First Timer

[Underdog1]

1) Nothing wrong with that plasigauge. That is down to the operator 
2) Never seen that tab before.
3) No need to soak parts in oil. Use a assembly compound on the shells and cam. A little oil on the bores.
4) No direction for chains, just staggered.
5) I will send you some more sealing washers for the alternator with the other parts.

Cheers Trigger you're the man! Would you recommend a semi synth oil for initial wear in after a rebuild? I'm sure I've read somewhere about mineral oil being good to use first off as it helps make the seals and gaskets more oil tight.. Cant seem to find where i got this from though!

[Trigger]

mineral is good for running in.

This is how I do my hoops, a plate for the seat to bolt to and indicator mounts. [ Guests cannot view attachments ]

[Underdog1]

mineral is good for running in.

This is how I do my hoops, a plate for the seat to bolt to and indicator mounts. (Attachment Link)

yeah I'm not done with the frame yet, i wanted to hold off having any plates welded on until I'd made the seat pan and figures out how I'm going to mount the rear mud guard like this:




Im also not going to be running indicators. Do you fab your rear hoops up yourself? Looks decent.

[Underdog1]

mineral is good for running in.

Is all mineral oil the same sort of stuff? I mean i could buy a cheap motorbike specific running in oil like this:

http://www.ebay.co.uk/itm/Motorbike-Running-In-Oil-Breaking-In-Oil-Mineral-5L-5-Litres-/111859859019?hash=item1a0b5dfe4b:g:Q4IAAOSw1S9Wf~xH

or I could go to home bargains and get something really nasty 

[Trigger]

Found this even cheaper >> http://www.ebay.co.uk/itm/Shell-Advance-SX-4-15w-40-4-Stroke-Mineral-Motorcycle-Engine-Oil-4-Litre-/370240162761?hash=item5634088bc9:m:mYkJhPLyxmonhvkSWF-7lOQ

[Underdog1]

Bit bored of looking at engine internals and as my bike frame is back i decided to make a start on the seat pan with my new angle grinder.

First i cut a template out of card


Then traced it onto some 1.5mm steel sheet


And then cut it out. To be fair it was easier than i expected even doing the curve, needs a little tidying up but considering this is the first time I've ever used an angle grinder I'm happy. Just started shaping the rear kick up a little, the metal is easy enough to bend with your bare hands.




Like trigger has shown in one of his previous posts i need to make a bracket spanning the frame tubes at the rear to bolt the rear of the seat to and the front.. not sure ye ill have to figure it out. Im thinking about cutting a flap at the front of the seat pan that will bend up and over the rear tank mounting bracket so the seat will sit flush with the tank (thats what that extra tab at the front of the seat pan is for, wanted to make sure i had enough material). Alternatively I could try and shape the metal like this:




Although i not sure i have the skills!

I was hoping to use the same sheet of metal to make the brackets that i need but if i am able to bend it by hand then I'm worried it will bend too easily which will be annoying after I've had it welded and powder coated. What mm thickness would you guys recommend?

[Underdog1]

Little more work on the seat pan today




Might have to change the front a bit as i want a relatively low profile seat and thats as low as i can make it to cover the bracket, not entirely sure how people get around this as some seats look pretty slim

[mike the bike]

How do people manage to ride with those skinny seats, do they put a wodge of foam down their trousers?

[Underdog1]

Got some loctite SF 7200 gasket remover stuff to help me avoid damaging gasket surfaces with a razor blade

http://www.loctite.co.uk/loctite-4087.htm?nodeid=8802627944449

Anyone used this before? Apparently it eats paintwork and as I'm not repainting now it's made m a little more reluctant to use it. I suppose I could spray it on and then immediately wipe down painted areas with thinners or maybe spray it onto a rag and rub it on to the gasket surfaces?

[Trigger]

Try using carb cleaner to soften the gasket, I buy a ton of this from a guy on the market at a pound a tin. You will still need a blade to take the gasket off but, it will be soft.

[Pops400]

How do people manage to ride with those skinny seats, do they put a wodge of foam down their trousers?

 

Big knackers tucked under.

[Pops400]

Please note, the above tip requires balls of steel.

Great thread, BTW. 

[Underdog1]

Jut had a little bit of time this morning to finish cleaning up the old sealant off the crank case mating surfaces with that lactate gasket remover stuff i bought.

Takes sealant\old gasket off well but it does affect paint, i knew this so i wiped any overspray off with some thinners but stupidly i didn't realise the inside of the crank cases were painted, i thought they were just discoloured with a gold tinge from 40 years of oil.. some of the overspray has stripped some paint:




Ive wiped down the inside with thinners but the more that i scratch at the paint thats lifting off the more is coming off.. Im not too worried about having bare metal inside the cases as its going to be coated in oil anyway but should i be worried about more paint flaking off? Anything you guys can recommend?

On the plus side i now have a paint stripper that actually works rather than the eco friendly stuff thats sold nowadays 

[Underdog1]

Hmm this looks especially worrying

[K2-K6]

They often used paint of various types inside castings to avoid any porosity in the metal allowing the oil to pass through to the outside. Not quite sure of the reasons it's used in these engines but someone else may be able to add more to it.

They were at the time trying to make them as leak free as possible in comparison particularly to British made engines. I guess you'd get too much drop out from production runs to even test them all, so easier to use an oil resilient paint in coating the inside to reach the consistent standard they were aiming for.