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Discussion Starter · #1 · (Edited)
Hello CB450 lovers! I've just got the membership and this is the first time for me to post a thread from Japan! Sorry for my broken English!

I found the oil pipe inside the inlet camshaft loose when I parted out the engine.
Should this pipe be loose or thght fit? If the pipe should be tight how can I stay it in its position?

SHOE SATO oil path pipe.jpg oil path pipe 2.jpg
 

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Sometimes they are sort of loose, but you should be ok - where is it gonna' go, after all???
Some folks actually remove it completely - not that I'm suggesting that.
 

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Discussion Starter · #3 ·
Thank you for your kind advice, Bill. As you say, hopefully, the pipe stays inside the camshaft and works fine. Or it doesn't matter if the pipe is removed... In fact, even if it is removed, the oil flows into the camshaft and lubricate the cam surface.
I'm just wondering why HONDA added this pipe? ... Anyway I will let it be loose and assemble the head..
 

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That pipe may be used to restrict the flow of the oil so as to
keep the pressure up in other parts of the engine. There is a
similar pipe in the clutch assembly of my Honda 50 and it's
purpose is to help maintain oil pressure.
 

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These old twins are not so big on oil pressure - it's no where near what we're used to seeing in automotive or modern bike engines.
Maybe 4-5 psi is all you will see, it's not really a pressure-driven system. i guess Honda thought it was adequate to the purpose, and saved space and money.
The tube is actually meant to deliver oil to the center of the cam's length, an attempt to get an equal amount of oil to both lobes on the cam.
I've known folks to shorten them (the tubes), others have completely removed them - I wouldn't do this on a customer bike, but that's just me.
 

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These old twins are not so big on oil pressure - it's no where near what we're used to seeing in automotive or modern bike engines.
Maybe 4-5 psi is all you will see, it's not really a pressure-driven system. i guess Honda thought it was adequate to the purpose, and saved space and money.
Actually, the main reason for high oil pressure in any modern engine are the plain bearings. They need a lot of pressure to function without contact between the bearing surfaces (they "flow" on oil once there is enough pressure). The bad side of this is that they will run "dry" when you start the engine, and they actually make more friction than roller or ball bearings (so not the best high performance thing). Even though they last longer and make the engine more maintenance free, I definitely prefer standard ball/roller/needle bearing engines, simply because the replacement is straightforward (on any >40 year old engine rebuild, you want to replace all the bearings when you have it apart, if they are plain or not). For plain bearings, you need to have the crank grinded (which may remove the surface hardening and make it susceptible to more wear), get undersized shells... Standard bearings are just more rugged - if for some reason your oil pressure dropped on an all plain bearing engine (f.e. oil pump failure) in higher revs, you definitely need some expensive repairs. A roller/ball bearing engine may even get away without a problem, if you quickly turn the bike off.


And the big advantage of standard bearings is that they need far less oil pressure to work. Even splash lubrication can work to a certain degree (big, low revving engines). I never rebuild a CB450 engine, but I am quite certain the crank fully supported on standard bearings, that do not need much pressure. However, I also assume the camshafts are not - and as far as I know, this proved to be a problem, as the pump does not build up enough pressure on a cold start. Being a DOHC design, the camshaft lobes are also not directly lubricated by an oil bath underneath, as on most SOHC designs (probably the CB350, I know the 360 has this...). I am sure they had their reasons for using plain bearing up there. Yet, if someone were to modify it to standard bearings and block the oil passages, that would mean you'd get more oil pressure directly on the camshaft lobes faster, and that would solve modst of these problems (but potentially open up new ones, as I said, I've never rebuilt or worked on a 450 engine - it may even have the cams on standard bearings, although I doubt it).


Edit: checked a bit, it seems roller bearing cam conversion is quite popular, especially for the CB350 (but also for the 450). However, the oil paths are usually still the same, so no more pressure on the cam lobes for the 450. Yet, it does reduce any wear upon starting the bike. Italian Cappellini can convert your stock covers for roller bearings for about 300€. However, if you are looking into converting such engines, a much better idea is to use their 500-600€ conversion to a modern oil pump (and also oil filter). It does not increase pressure (because it is not needed), but it pumps a lot more oil volume than the stock pump. You can even fit an external oil cooler (which is in my opinion a bad idea without a thermostat).
 

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Discussion Starter · #8 ·
Thank you Bill and pikl for the detailed explanations on oil pressure. I am a beginner on rebuilding the 450 engine and I have little knowledge on oil pressure, however now I understand the concept of the manufacturer. Now I can imagine "the dry start" , awful isn't it? I could never do this any longer!

Thank you again for letting me know one solution for this! I'm really excited! The Cappellini products are the realization of what many people had dreamed of!
Even if the the pumping ability to supply to the top end is poor, they surely reduce the friction and reduce wear on stating the engine.
 

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Discussion Starter · #10 ·
oil pipe3.jpg

Watching the picture, I've just noticed that if the pipe moves freely in the comshaft and depending on its position, it could block the oil path hole to the cam surface...
As Lefty suggets, loctite the pipe would be a good solution! Or if the thickness of the pipe were increased, it could press in and stay fit....
 

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It does not show up as separate on the parts diagrams, so probably was meant to be pressed in, and never removed. Fixing it in place seems a good idea, to me.
 
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