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1967 CB450K0 Black Bomber Rebuild - By Royhall
royhall:
On the four speed it is okay to use the four bearing carriers that came with the crank.
I used the same guys as you did Dave to get the crank rebuilt and cleaned, D&M Engineering who were sure I could take the crank out of one set of cases and straight into another set. They said it was full of the same black goo that covered most of the engine but all parts were in tolerance and good condition. Glad I had it done as I wasn't going to bother, but that goo would have destroyed it as soon as it was fired up. So money well spent.
As the crank simply hangs from the top crankcase on studs located by a machined cut out, it has no matching machined parts in the lower unlike any of the other shell bearing Honda's. So happy days.
Bryanj:
250 and 400 wet dreams lower case was just a cover the shell bearings were held by a machined with top case carrier.
royhall:
Ahh yes the wet dreams I had forgotten about them, or did my brain block them out. A fantastic bike but I just didn't like them.
Laverda Dave:
Looking good Roy. I agree with you about vapour blasting, I think it's OK to do as long as you trust who's doing it and wash, wash and wash the cases when you get them back. I use I Cleenz Machinez, not cheap but they do a fantastic job and are bikers themselves.
royhall:
Moving on. I got all the parts nice and clean, it took some effort with the gear clusters. I was reluctant to use a solvent to clean them as it can sneak into all the little openings and cause damage. In the end I used a thin machine oil and a new paint brush, worked really well and got them really clean as you can see in the photo. I then blew them out with compressed air and spun the bearings, they are perfect condition so I just gave them a good oiling with clean engine oil. The gears and shafts were also as good as new so the whole assembly can go back in as is.
The casings, barrels, and head were painted with Simonize VHT silver except for the lower crankcase that was left unpainted. Guess that was a Honda cost saving move? The postman has been busy delivering parts from CMS, Silvers, and eBay. I spent a while checking what was there and writing on the bags what the contents were for. I also sorted them roughly into the correct order of use. See I'm finally learning that forever sorting through a big box of parts looking for one item is frustrating. An hour well spent.
I started the assembly with the top case upside down and got the crank, gearchange barrel and gear clusters into place. I used all new shaft bushes and assembled using Graphegen and oil. For a sophisticated (for the day) engine it is actually a very simple bottom end to assemble. Clearly Honda gave the assembly a lot of thought. You will probably remember that the crank had been previously rebuilt by D&M Engineering so was ready to go straight in, although I took the liberty of generously lubricating it all with the oil can. I found it a bit nervy tightening down the crankshaft as the quoted torques are pretty high and I was afraid of stripping a stud. So much so I checked the torque settings in four different places and tried two torque wrenches in the vice first. All went well in the end though.
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For the sharp eyed amongst you, the bag marked "spare bits" is not bits I forgot to put back in. They were duplicates from the replacement crank cases.
The lower case contains the kickstart mechanism that was a bit fiddly to assemble but not too much swearing. It was all assembled with new circlips and seals, and again with Graphegen and oil. The lower case is basically just a cover and slips over the studs and is located by two dowels. The joint was sealed with a thin coating of clear silicone and tightened down using new stainless nuts and washers. The studs are tightened from both the top and bottom of the cases.
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At this point my home made plywood engine stand comes into play, and a thing of beauty she is to. All's looking good so far, next up is the pistons, barrels, and clutch mechanism.
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