Engine rebuild questions

[Greg65]

Oh dear oh dear Julie, what have you started!

My wife is convinced I’ve got an internet girlfriend as all she hears is my god Julie is fantastic, she snatches the iPad and sees pictures of engine bits. I then get accused of closing what ever I had been looking at previously! Oh well.

Anyway you have given me the confidence to persue the camchain tensioner suspicions. So far I have the head and barrels off and getting stuck into the cleaning. All this is leading to the first of many questions for the experts.

First up. The circlip  that retains the tacho drive. How do I remove it?

Second. Cleaning carbon off exhaust valves. Have tried soaking in diesel for a few days. It’s still solid and reluctant to go to physical with it. Also cleaning up the piston which is a much softer metal, advice please.

Also may I must add my thanks and admiration for a really good thread and finish you have achieved. I now understand why you moved from Kent to be very near Trigger. 

[Nurse Julie]

Haha Greg, your wife need only start worrying if you and I start swapping fairy cake recepies or discussing nail varnish colours.......worried for you that is, not me 
The tacho circlip should come out easily enough, it is easily accessible, just keep digging. Try soaking the valves and pistons in thinners, it should remove most of the carbon which will be a start.
No, I didn't move up this way to be close to Trig, although it is very handy when it comes to engine building, we moved up from Kent together 
Good luck with your project, you will enjoy it.

[Greg65]

I have a Kentish lady from Stodmarsh, one is enough.

I have found the circlip for the tacho drive. Now does anyone know if I push it into the cylinder head cover or rotate it and pull it off with pliers?

Will pick up some thinners tomorrow.

Thanks,
Greg

[Nurse Julie]

I have a Kentish lady from Stodmarsh, one is enough.

I have found the circlip for the tacho drive. Now does anyone know if I push it into the cylinder head cover or rotate it and pull it off with pliers?

Will pick up some thinners tomorrow.

Thanks,
Greg

Rotate and pull off with long nose pliers.

[Greg65]

Can i have some opinions on my cam shaft please.

[Greg65]

and the other half.

All the other bearings are similar. Use, refurbish or a pile of scrap?

[Orcade-Ian]

It really depends on how much you want to spend and more importantly what you intend using the bike for when it’s done.  In an ideal world you would either replace the camshaft, head and cover with new.  Another route would be to have the cam metal sprayed and reground to size but the head and cover are almost impossible to reclaim due to the specialist machine Honda used to produce them - they can’t be line bored with those blind ends.

Now to the real world:  I’ve seen much worse on nicely running bikes and if this bike is only going to be used carefully and not on a daily commute of hundreds of miles and providing the measured radial bearing clearance is within limits then I personally would use those parts again.  The other question I would have is are you replacing, or at least checking big ends and mains and oil pump - they have had the same diet of contaminated oil?

I’m sure Trig will have strong views on this

Ian

[Greg65]

Thanks Ian. I will get the micrometer across the part tomorrow and post the details.

Now back to the tacho drive. After a bit of a wash the circlip stuck it’s nose out far enough to come out easily. Any tips on how to release the old seal as it seems to be “welded”, or to I just dig in.

Thanks,
Greg

[Nurse Julie]

Put a flat blade screwdriver through the hole and on the the underside of the lip and prise it up, if it doesn't budge, pick at it. I had a seal that was well stuck in place, got it all out in the end.....in 87 little bits 

[Greg65]

Orcadian. Yes the big ends will be inspected  and bearings replaced. I will also strip and replace seal in the oil pump. The cam measures within limits so I will reuse.

VHT paint. Rattle cans, if so how many will I need? Or use a spray gun, if so which paint is recommended?

The copper washers that are used on the cylinder head, can they be annealed and reused?

Thanks Greg

[Nurse Julie]

The copper washers can be annealed if they are solid copper. Mine were copper covered steel so I reused them. 8 'O' rings needed  for total overhaul of oil pump, I sell the kits if you need one. (Obviously you don't have to buy a kit from me, if you don't want to !!!!)

[MrDavo]

My CB750 tacho drive oil seal was leaking, rock hard with age and stuck.

Following advice from this forum, I think, I drilled a tiny hole in it and screwed in a small self tapper. That was to give me the purchase to pull the bugger out with pliers, IIRC what actually happened was that when the self tapper bottomed out in the blind hole, continuing to screw it forced the seal off its seat and out towards me - it was then lobsided but I got a small screwdriver in behind it and popped it out.

I've seen far worse than your cam bearings in sweet running engines, if it ain't (that) broken don't fix it.

Ive scraped carbon off valves plenty of times, just stay away from damaging the seating surface and stems. I've even cleaned them up with emery cloth and a blunt screwdriver end after putting them in a drill chuck, protecting the stem with a bit of rag, probably not best practice but it has worked for me.

[Greg65]

How is it that such a small part can cause so much grief. Going for the Julie 87 bit removal process I’ve managed to remove the front third of the seal, still welded. Applied penetrating oil and tried flexing the seal by applying pressure with a screw driver between the tacho drive and the cam cover to push it out. Got some movement so thought I would pull using the pliers. WRONG.... I now have a broken shaft, oh for f#&%£ sake. Any one got a used one for sale? Finally removed the remains.

Yes Julie would love a set of seals for the oil pump, thanks, PM sent.

My wife casually mentioned that a friend of hers husband rebuilds old car engines and has a small engineering business. So after an introduction I’m visiting a workshop with measuring devices that I do not posses next week with a selection of parts. This hopefully will give me a good idea on the condition of the bores and general condition of the engine my inexperienced eye does not have.

I now have a nice set of clean valves which are in good condition. The shafts all measure well within limits, showing little or no wear. Thanks for all the advice.

[Nurse Julie]

I may have a spare shaft, I will go in the workshop and look after I have cooked dinner.

[Nurse Julie]

I think you may have had the original Oil seal fitted Greg, a metal band encased in rubber, like this one

[ Guests cannot view attachments ]

No point crying over spilt milk, it just so happens I am giving away a replacement with every CB400 oil pump O ring kit this month......limited supply, last one left 

[ Guests cannot view attachments ]