CB750 Barn find project - First Timer

[Underdog1]

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.

Makes sense I suppose.

My concern is how likely that bubbled paint is to lift off eventually and block oil ways.. maybe I should just strip it all off (well all the stuff that's bubbled anyway)

[hairygit]

Personally I would remove the loose/bubbled paint, any solid debris breaking loose inside the motor can cause havoc. Even if it doesn't block the pick up gauze on the pump, do you really want it gunging up the gear clusters and gearbox bearings?

[Underdog1]

Personally I would remove the loose/bubbled paint, any solid debris breaking loose inside the motor can cause havoc. Even if it doesn't block the pick up gauze on the pump, do you really want it gunging up the gear clusters and gearbox bearings?

Yeah I don't want to stick it all back together only to shart itself within 5 minutes. I'm going to try and get some sandpaper into the gaps at the front of the upper crankcase and see how easily it comes loose

[Underdog1]

Following on from the above I've given it a good hard scraping with a sharp screw driver and the bubbled paint is absolutely rock hard and definitely doesn't want to come away. It's like the gasket remover has just wrinkled the paint up. If the paint is looking like it wants to stay on could the wrinkled/bubbles paint cause any problems with oil flow where it is (in the recess in front of each cylinder in upper case)?

[Underdog1]

Right I'm back home again, got a week off too so I can work on this heap 

Got the crankshaft, gears, countershaft, gear selector bits, kick start and final drive in today. Just need to source an o ring for that dowel thing for the oil gallery at the front of the crank cases and I'll be ready to close the bottom end.



The gear selector gubbins took ages, seem to have them in right now though.

I've used graphogen on the crank and bearing shells, I applied it relatively thick and from just placing the crankshaft into place its oozed out onto the case mating surfaces.. do I only need a thin layer of this stuff? Anything else I need to think about pre lubing?

[Bryanj]

Tat O ring should be 18 x 3

[Underdog1]

Tat O ring should be 18 x 3

Yeah seen, turns out I had been sent a 19x3 by accident

[Niko]

Check out a motogadget m unit to simplify wiring as an option


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[Underdog1]

More progress today, closed the cases -



And then built up the legal linkage and alternator bits.

BUT

For some reason I've had an absolute nightmare with the clutch cover..

I just can't get the bloody thing on! The dowels are in the crankcase and I can get the right side of the cover lined up but the left side is always too high, it's like the kickstarter shaft is pushing it up too far.





If I've some how mis aligned it whilst assembling and have to split the cases again I'm not going to be best pleased! Suggestions welcome 

[Trigger]

Your kick start shaft is too close to the clutch basket. Put the clutch cover on, then the kick start lever, turn the engine with the lever while pulling it back and locate the cover up. If that doesn't work, report back.

[Underdog1]

Your kick start shaft is too close to the clutch basket. Put the clutch cover on, then the kick start lever, turn the engine with the lever while pulling it back and locate the cover up. If that doesn't work, report back.

Sweet that sounds easy enough, however my kick start lever is 160 miles away so will have to wait until the weekend when I'm down that way.

I'm in my Mrs' bad books for getting graphogen on the carpet 

[Trigger]

you also need the shaft holder fitted to the left side, to line up the gear box shaft

[Underdog1]

you also need the shaft holder fitted to the left side, to line up the gear box shaft

As soon as the kick start was on I could manoeuvre the spindle easily to get everything lined up

Just installing the base gasket (vesrah) and it doesn't quite fit properly. It's the right one but the hole for the camchain is slightly off centre, should I trim a little off to give a little more clearance for the tensioner on the left side or just leave it?

[Trigger]

Turn the base gasket over, it should fit better

If you get the rocker cover gasket on the wong way wound  it will leak

[K2-K6]

https://www.cromwell.co.uk/shop/lubricants-and-chemicals/industrial-cleaners-and-solvents/amberclens-anti-static-foaming-cleaner-400ml/p/AMB7010070S?utm_campaign=pla+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=AMB7010070S&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=aqrxtqtxw&istBid=tztt

This is useful for the "Graphogen on the carpet" also for getting the smell of puke out of car interiors if you've transported young children. Although I could see too many occurrences of Graphogen on the carpet leading to  lacking the opportunity of "practicing" for children.