CB360 Head issues, what are my options?

A

Athis

New Member
Hello all,

Second post here besides my brief intro and hoping to get some advice/feedback.
My CB360 was in running condition ( and in fact ran really well), however, I decided to rebuild it/fabricated from the ground up myself.
Today I started tearing into the engine....which was intact and running before I started. I ran into this when I took off the heads.

As you can see, the bearing journals seem shot. I want to understand my choices before I proceed. Obviously I can purchase new (used) parts.
Can this be fixed my machining? Can the Journals be re-bored perhaps sleeved?
Also I think the cause of this was lack of oil to the head. Either the pump quit or got clogged. Or maybe the previous owner ran it with low oil.
Right now, I'm pretty sure checking the pump for proper function is essential no matter what I do, as it will ruin what ever new/fixed parts I end up using and I don't want to take that chance.

I really need your thoughts and feedback on this as to whether I'm correct in my thinking and or what other options there may be available to me.

Thank you guys for this awesome site! :)





 
Scrap , start over . By the time you got all the journals , rockers , cam replaced you would have a new head at 4 times the cost of a viable used one .

~kop
 
What kop, said. You can certainly salvage what you have, but the repair costs are much higher than the price of second hand parts off of eBay.
 
Yep, look for a replacement, although if you know any machinists it's worth getting it fixed
Should be able to pick one up around $50.00?
Pull off the clutch cover and check the transfer piece inside, they have been known to come out (you'll have to remove cover to check oil pump and pick up screen)
BTW, top right valve spring is in upside down
 
Thank you guys. A couple of more questions...

If a machinist did work on it would he bore out the bad journals and use some sort of shim to make up the diameter difference.

And also, if I pick up "good" parts from ebay, how do I know the 2 parts will form a unified circle when put together? Is it not that important?
 
The head gets line bored for ball bearings on both ends (same size as oil seal outer diameter)
Center will probably break through to airway underneath so needs a 2 piece thick wall bronze bushing made which is 'glued' in position
Rockers can be built up and re-ground with hard face, cam needs specialist repair though
 
Understood.

What about purchasing a head and a head cover, separately from ebay. Will both heads ( if in decent condition) be "round" enough in terms of the bearing journals for the cam to function properly?

OR do people purchase a used match set of head and head cover?
 
Ok so last update on this since I have enough info now to move forward on this.

Latest God send is a friend of mine has a 74 CB360 sitting in his back yard. Over the years I've done lots of favors for him, and he called me tonight after seeing my Facebook pictures and gave me the bike for free. Someone up there really must like me I swear.

Regardless, one thing i didn't mention is that I am a machinist/fabricator and I may end up making a fixture to bore this thing out and replace it with bearing as you suggested. If anything I want to see the end result of that type of modification, so I'll throw it up on my cnc and see what I can do. Who knows, perhaps I may be able to help others in the future and not charge them an arm and a leg for this type of work.

As I post for help, these types topics will be here and there, but I promise in the end I will throw a build thread together and share my end of some of this information with you guys as well.
Thanks for the response, It is greatly appreciated.
 
replacing the end bearings with needle bearings isn't all that hard, if you've got an angle plate, it's an hour or two, mostly setup. I never found a suitable inner race for the needle bearings though, so wound up turning down the stock cam bearings and fitting an 0-1 sleeve hardened to something like 56rc, was a total pain in the ass, but running the needle bearings directly on the cam caused it to tear up pretty badly... in the end, the top end oiling failed anyway so the rockers welded to the cam lobes... bearings still spun freely, but I guess that was the next weak link
 
Yeah, I suppose finding the right bearing would be the key. Although there are so many types, it's hard to say if there is a specific one that fills all the criteria.
The work itself isn't that big an issue. If I did it, I would make a fixture that aligned the camshaft perpendicular to the machines table. Once the heads are fastened together, I could bolt the head which would be pinned in place to the fixture, dial in the bore to zero it out and bore the journals to what ever size the bearing would be.

The center journal seems to be the one that's a pain. It would have to end up with a babbit as mentioned earlier. And although I'm not a big fan of bonding it in place....there's really no other way of doing it unless you were willing to machine away more of the mount in that particular area and fasten it in a completely different fashion.

I can totally see why people just buy the parts. ;)
 
I just left the center journal alone, except for adding the oil feed hole which the casting seems to be designed for, but honda never made... bored each end bearing from each side, I think trying to bore that far with such a small bar would make it chatter
 
Your correct if a standard boring bar is used given the fact that it's roughly 7 inches deep.
But there are insert cutter bars designed to cut a specific diameter range with a +- adjustment of .1 or so.
The range is limited, so the boring bar is job specific in nature, but the trade of diameter limitation is made up by the solidness of the shank which prevents chattering.

Edit; Just joined ya on Facebook. Great work man, love it.
 
I would make a bar and some guide bushings, you would always have support with minimum overhang
 
Update:

So I've had the engine sitting off to the side while I've been fabricating my solo-seat. The "donor" bike finally showed up. It was in pretty bad shape. I pulled the motor, and ran into the same issue as mine, albeit, not as bad.

So, is this a normal issue with the 360's?? This "donor" bike has 6k Original miles on it! How the heck did this happen? It's starting to look like a serious design flaw on Honda's part by not drilling out that center oil port.
 
Back in the 70's 'we' thought it was oil breaking down but really the main problem was people using way too thick an oil plus not warming motor before revving it. motor is designed for 10w, using 20w/50 or straight 30 or 40wt will destroy top end pretty quick
The real problem is the oil transfer piece in the clutch cover, I've posted pics of modifications.
I use 5w/40 full synthetic oil with 2oz ZDDP added but you need to fit heavy duty clutch springs
Without oil flow it doesn't matter how many holes you drill
 
Crazy, I would love to read your thread on the oil transfer modification. Can you please link that for me?

I hadn't thought about people using thicker oil, or not properly warming the engine. That makes sense, I can see that leading to this issue as well.
 
I have this discussion on some truck forums I am on. they think Ford is crazy specing 5w-20 oil. they put heavier oil in and think they are helping. If you measure pressure at the pump, heavier oil gives more pressure. But if you understand hydraulics, more pressure is actually less flow, not more. The passages and orifices in the block and cylinder and heads are designed to flow the correct amount of oil to the ares needed. The engineeers design the orifice size based on the viscosity of the oil. When you put a heavier oil in, the orifices allow less oil to flow. The restriction makes the presuure at the pump higher, but the overall flow lower. The further away from the pump, the less the flow. The head is furthest from the pump.

CrazyPJ's drilling of the hole in the top crankcase half, where it feeds the passage tot he head, is the correct way of increasing oil flow, even with slightly heavier oil.

The other job of oil is to remove heat. Thinner, faster flowing oil removes heat faster then thicker, slower flowing oil. So thinner oil (the weight called for in any manual) removes more heat then thicker oil.

Never rev any engine on startup....idle a minute to allow oil to get through all the galleys and passages and lubricate everything before giving it the stress of revving it.
 
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