CB400/4 ENGINE STRIP, ASSESSMENT AND REBUILD BY JULIE - NOW COMPLETE

[kevski]

I use some super sticky double sided tape that we used for sticking grinding stones to their face plates when i was a plating tech, you have to use a good solvent to remove it though.

[Nurse Julie]

Chuck type tap wrench, attach to the other end of the valve and pull the valve against the seat rather than push it against. Works much better as you can really get a good pressure on there so speeds the job up.

It took me so long Ken I was tempted to stick the plunger on the end of my Frappe whisk and have a go with that 

[Bryanj]

You used to be able to buy a tool that one end went in a drill chuck whilst the other had a rod with sucker and the box in the middle converted rotating motion to back and forth

[Nurse Julie]

You used to be able to buy a tool that one end went in a drill chuck whilst the other had a rod with sucker and the box in the middle converted rotating motion to back and forth

Like this you mean Bryan

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Trigger said why didn't I use this...... after I had spent hours lapping them in by hand  . It was in another tool chest that I had never looked in. Fits in a pillar drill and the head sits in a stand that holds it horizontal but with the valve vertical. So, just pull the pillar drill down with this attached to it at low speed. Oh well, I will remember it for next time.

[Nurse Julie]

Continued working on the head today after yesterdays lapping in. In theory and also in practice to most of you, getting the valves in is no problem I'm sure and even I was thinking here is a nice little job to do. But, gosh, did I struggle big time.

The theory..... 1) Put outer seat over valve stem. 2) Put inner seat over valve stem. 3)  Fit valve stem oil seals on the inlet valves.   4) Put smaller spring over valve stem. 5) Put larger spring over the smaller spring. 6) Place retainer on top. 7) Insert cotter valves.  Compress all together with the valve spring compressor.
(I have no idea where the smiley chap with the shades came from, it's supposed to be a number 8.......can't delete or change it either  )

Well, No's 1 to 7 no problems at all. The big problem came when I was trying to use the valve spring compressor. Firstly, my hands are really very small and as you would expect, not as strong as a mans. I was struggling that much the compressor kept moving around when I was trying to compress the spring and the cotter valves kept dislodging and falling out, even though I had put grease on them to hold them in place. In the end I only managed one complete valve and that took ages and an awful lot of swearing. I had to ask Trig to do the rest for me. Utter failure on my part, most disappointed in myself.

This pic shows the valve stem oil seal in situ on the inlet valves before putting all the other bits on

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And here it is all finished. I managed the one right end of the bottom row !!!

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[Laverda Dave]

Well done Julie, at least you tried and managed one valve, it's not easy. Fitting valve springs etc is one of those jobs where you need to use your bare feet to hold the springs in place whist one hand holds the spring compressor and the other hand fits the collets. It sounds difficult but you'll soon get the knack of it with practice and a visit to an osteopath afterwards. .

[Nurse Julie]

Well done Julie, at least you tried and managed one valve, it's not easy. Fitting valve springs etc is one of those jobs where you need to use your bare feet to hold the springs in place whist one hand holds the spring compressor and the other hand fits the collets. It sounds difficult but you'll soon get the knack of it with practice and a visit to an osteopath afterwards. .

That's where I was going wrong then, I still had my socks on 😁😁😁😁😁

[kevski]

I have just looked at that head and wondered how Honda machined the bearing journals, naturally the cover and head are matching, i can speculate how it was done but does anyone know for sure, all of my big Kwaks have been line bored, and many of the other marques of bikes are line bored including Hondas so how were these done?

[matthewmosse]

It is indeed a royal swine of a job. My valve compressor is a G clamp and a bit of gp100 fork with a slot cut in it. If 8ts seated just right you can put the head down on a worktop and use both hands to get the college in, but if it ain't quite right it slips off and you are searching the floor for the bits that got launched. Brings back memories of my first cb550 engine rebuild, similar head damage and pistons but all 4 equally dead. My workshop was still in early build phase so I was stood in a muddy puddle using an old sideboard as a work bench. Had to get it back running in 3 days start to finnish so no nice machined bits just whip it appart, lap the valve seats and bung in new pistons, clean out broken rings and sludge, check gearbox for debris and thrash the bike round the top of  Scotland and back. It put me right off doing head overhauls especially as engines from breakers were cheap up to fairly recently.

[Clem2112]

I have been curious as to how Honda machined the head and cover journals... for 40 yrs !
Nobody seems to know for sure but there are places that can do it in the UK , I hear from other restorers.
The only way I can see that could feasibly achieve the fine finish and tolerance would be a single point cutter but the setup would be very slender. Unless they used a ball end mill and profiled each in turn?

[Bryanj]

I think the machining was done on a vertical mill with a Tee shaped drive box and sized cutters plunge milled, it is after all softish alloy

[Clem2112]

About the cam journal nachining....

Think Bryan has it. Honda had to have a dedicated setup to do the quantities they produced.
A fast, cheap method using a sized cutter makes sense.

The anoraks among us would like to see some period footage showing the machining of Honda engine castings.

[Nurse Julie]

Did some more building today, nice little bits to play with and thoroughly enjoyed myself.
Put all the bits back in the rocker cover. These are the bits I started with

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Fitted the flywheel and took the clucth apart and gave it another clean before reassembling

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I still have to fit the clutch lifter bearing. I have one here but I ordered the wrong one, so have ordered the correct one today.

The rocker cover re assembled with the tacho drive back in, held in with a minute little circlip and new seal fitted

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Everything is all torqued up and the bottom end is now ready to go back in the frame and all the top end components are reassembled. I will refit the oil pump later today along with the neutral switch. The only thing I have not had done yet is the rebore as my pistons and rings are stuck in customs, so the rebore will be done after Christmas or early in the new year.
I must be getting somewhere because I had all the parts in 4 big Lin bins and I am now down to a very few parts in the bottom of 1 Lin bin.........getting there.


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[UK Pete]

Did some more building today, nice little bits to play with and thoroughly enjoyed myself.
Put all the bits back in the rocker cover. These are the bits I started with

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And here is it all together

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The tacho drive, held in with a very small circlip and greased and a new seal on the outside.

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Fitted the flywheel and took the clucth apart and gave it another clean before reassembling

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I still have to fit the clutch lifter bearing. I have one here but I ordered the wrong one, so have ordered the correct one today.

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Everything is all torqued up and the bottom end is now ready to go back in the frame and all the top end components are reassembled. I will refit the oil pump later today along with the neutral switch. The only thing I have not had done yet is the rebore as my pistons and rings are stuck in customs, so the rebore will be done after Christmas or early in the new year.
I must be getting somewhere because I had all the parts in 4 big Lin bins and I am now down to a very few parts in the bottom of 1 Lin bin.........getting there.

This is really getting me in the mood for a engine build I have 2 apart and preped ready to start assembly but it's been a few years a move if house and a shit load of personal problems I really don't ķnow where all the bits are
Well done so far I have just spent 90 mins going through unread posts on this thread . You are quite lucky as in you have access to good quality tools and triggers knowledge  but I admire  that you will only use him if you really have too
Keep it up julie

Sent from my SM-G930F using Tapatalk

[GiannisFour]

Julie,
a question,what brand gaskets,o-rings and seals are you using?
Thanks