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Discussion Starter · #1 ·
I rebuilt a CB450/500T bitsa a while back, and I noticed at the end of last summer the engine was making a lot of cam chain noise. I tightened the cam chain adjuster, but as it was still making lots of noise, I pulled the top end off.

I was not heartened to see the exhaust cam and followers were scored and worn badly. Even the cam bearing surface was scored (enough to feel with a fingernail). I had changed the oil multiple times, and was using a good synthetic, and the oil filter and sump weren't dirty, so I had no idea why this happened.

I found that one of the rubber o-rings around the exhaust cam had come apart - found big chunks of it stuck here and there, so I assumed I'd clogged an oil passage somewhere. However, I didn't find a single clog when I pulled the engine apart.

I cleaned out the rubber bits, and bought a decent set of used cams and was going to put the top end back together until I found the master links I bought from Z1 were not a match. Since I haven't ridden all freaking summer, I was pretty pissed off - more delays.

Then, I recently read a thread over at Caferacer.net that talked about vintage racing and the tendency of honda 350s and 450s to score cam bearings and faces when run at high speeds for extended periods - something I had been doing on my own 450, commuting in rush-hour traffic (you get run over at 70MPH). This led to a thread here: http://caferacer.net/forum/topic.asp?TOPIC_ID=15805 where we discussed how people who race CB450s all end up modding the existing top-end oiling with external oil lines, and a Cappellini oil pump or mods to the side cover to add external lines like this:







Basically, one line, closest to the case, taps into a small chamber that feeds the original oil lines to the head. The other, optional line is a return to the case for an external oil cooler, or perhaps an external oil filter like this:



The lines to the cam bearing caps pump oil straight into the cams - you can see here where they simply used a left-rear bearing and replaced the tachometer cover.

The old feed lines to the head get blocked off, at the base of the cylinders, and at the feed holes on the top right side of the head.

I had an enlightening conversation with lordmoonpie from the sohc4 forums about this very subject, as he raced a 450. I also wanted to get some thoughts from the 450 experts here - anybody here with any thoughts on this?
 

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Sensei
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You have the basics, but the "other" line is NOT optional... To simplify this discussion, let's look at the red (and white) bikes oil plumbing......
The oil is picked up in the sump and pumped through the centrifugal filter.... Normally it would go straight from there to the main cases where it would be divided by orifices to flow to the top end and down through the bearings, tranny, etc...... On the red bike, the two lines attach to the outer case along that main passage and there is a block in between them... This forces ALL the oil through the cooler and on its exit, some of the oil is sent to the top end through the cam journals, and some returns to the main cases.... The top end feed from that "pocket" in the main cases is also blocked, (the top is already getting its oiling) so all the remaining flow feeds the bottom end stuff.....Without that "optional line".. your bottom end would lock-up rather quickly.......
 

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Discussion Starter · #3 ·
So how does that other example work? (the black-and-white pic) There's no return feed there. 66sprint, have you built an engine like this? Any thoughts on the oil lines to the head in terms of total flow needed/line size?
 

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Discussion Starter · #4 ·
Also, I'm assuming it's better to run a line to the exhaust side first, since it seems that's the cam that gets beat the most. What do you think about my high-speed commute theory? Seem plausible?
 

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Sensei
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In the B&W pic, the oil line just replaces the internal passage upwards.....It has a different filter (Capellini) prior to the junction... The advantage of this is the oil to the top dies not directly come into contact with the cylinder heat as it's getting there...
No need for a return as the oil is already at the "pocket", it splits there as usual, just goes exterior...
Line sizing and orifices are mathmatically determined by/from the flow rate/pressure of the oil pump being used.....
 
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