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Discussion Starter #1
Anyone have a good diagram showing the flow of oil through the engine, especially the head?

The reason is just out of curiosity and wanting to learn. I just had the valve cover off my '80 Hawk to check the valve clearances and had a look around. Couldn't see how the oil got up there and around everything. Can someone put my mind at ease? :D

Thanks
 

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That's one of the few bikes I don't have an actual Honda shop manual for.
Most of the old twins send oil up through the cylinder/head studs.
Probably something similar on yours.
 

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Are there any common or easy things to do to increase the oil flow to the head besides additional oil lines?

Someone had mentioned opening up some holes? I also remember someone said on the 450s, you can cut something off the tachometer drive shaft?
 

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Flugtechnik said:
Are there any common or easy things to do to increase the oil flow to the head besides additional oil lines?

Someone had mentioned opening up some holes? I also remember someone said on the 450s, you can cut something off the tachometer drive shaft?
I've heard that you can cut the end off of that shaft (about 1/2" or so), and totally remove the one in the intake cam (on 450's) - Honda calls them "flow restrictors".
Now, why you'd want to restrict the oil flow on a bike with about 1psi of oil pressure (not even high enough to warrant a pressure gauge) is beyond me, but ol' man Honda generally knew what he was doing.

I can't comment on those modifications - I did it on my current 450, no results to report so far except that it's still running.
But I wouldn't do it on a customer bike based solely on anecdotal reports......
 

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So the oil comes up through the studs, into the cam covers and then into the cams? Then it comes out of the cams onto the cam followers and drains down?

What is restricting the flow?
 

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Flugtechnik said:
So the oil comes up through the studs, into the cam covers and then into the cams? Then it comes out of the cams onto the cam followers and drains down?

What is restricting the flow?
That's correct - you'll see the "restrictors" when you have the cams in your hand.

Actually, the oil passes through the far right studs on a 450 - both the right side studs have copper washers.
 

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Discussion Starter #10
Still don't have the path fully in my head (I'm a bit slow :) ), and I like to have a visual so I fully understand. Just looking around the net for pics of the separate engine parts disassembled to see if I could see the path. I found a pic of the upper engine case that shows the stud holes. Two of the holes (one on each side) have a channel that looks like it's the feed for the oil, am I correct? I've attached a pic to show. If so, how then does the oil get back down into the case after its been in the head? Through the cam chain section?

 

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Discussion Starter #12
gs1327 said:
that is correct.
Oil gets back to the cases via the cam chain area in the middle.
Perfect, thanks.

Now one last question about this. I meant to ask this back when I was polishing the valve cover. What is the purpose of the metal plate that is bolted to the valve cover? Is it for heat dissipation?
 

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Discussion Starter #15
I ran the bike for a little bit yesterday and then removed the valve cover to check the valve clearances again (just to make sure :D ) and I noticed that there was more oil on the left hand side of the head compared to the right. Is this normal? When I ran the bike it was on the center stand so gravity never really had anything to do with it. Everything was wet on the right side, its just that there was less oil pooled in the various recesses.

Am I just being too neurotic? Or should I check out the oil passage to the right side? If so, how should I go about it.

Is there anyway to do a check to ensure proper flow?
 

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tbpmusic said:
Flugtechnik said:
So the oil comes up through the studs, into the cam covers and then into the cams? Then it comes out of the cams onto the cam followers and drains down?

What is restricting the flow?
That's correct - you'll see the "restrictors" when you have the cams in your hand.

Actually, the oil passes through the far right studs on a 450 - both the right side studs have copper washers.
I still don't see what is restricting the flow, other than the small holes in the cam lobes.
 

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Sensei
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That would be them..... They are small to insure that there is enough pressure to get the oil all the way across the camshaft so both sides and all the lobes get lubed
 

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On a 450, this is what you're looking at -

In the photo, part #3 has the "restrictor" for the exhaust cam.
Various people have cut that shorter - I've heard in either of the two places indicated by the dashed lines.

On the intake cam, there is a similar tube-shaped thing, but it's pressed into the cam. To remove it, jam a lag bolt or some sort of screw into the right end of the cam and pull that thing out. Or alternately, pound it out from the other end.
The word is to leave that one out completely - be sure to mark your timing mark on the cam, because both ends look pretty much the same after this thing is removed, and it's easy to lose your left/right orientation.

Most of this info is either anecdotal, or from first-hand reports.
My only personal experience with this has been on my current 450, where I cut it (exhaust) midway between those dashed lines.
All I can report is that it hasn't seized up yet.

So try it at your own peril...........


 

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You cut the intake restrictor Bill? You did nothing to the exhaust cam?? I was under the impression that it's always the exhaust cam that has the oil flow problems and wears out the followers the fastest...?


GB :mrgreen:
 

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Sensei
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Uh Bird.... The tach is on the exhaust cam.....
 
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