Honda CB750 Sandcast

Chris Rushton's High Mileage Sandcast

Steve Swan

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This thread is from Chris Rushton. His bike is pictured on the Main Page, on the roads of the Isle of Man. He has written VERY interesting comments.

"For your interest hopefully, I have attached a picture taken of my "regular rider" sandcast, serial number 1005298, E1005192, taken on the Isle of Man during TT 2004. I have owned this bike since 1989. When it came to the UK, it was 80% original and was showing 22,000 miles which I would suggest was probably correct based on its general condition at that time. Following a re-build, it has been in regular weekend use (April to November) every year since then and is now showing 82,000 miles. Over the last few years, the annual mileage has been increasing, 7,000 miles having been covered in 2004 alone. It is not a show bike, it is used in all weathers, but I do try to keep it mostly in original condition. As a concession to its past, I have never removed from the left hand fork lower the "University of Southern California" parking sticker which shows an expiry date of 30th January 1972!
I do ride other Hondas, both modern and classic, but can honestly say that the CB is the best of them all. Trips planned so far for 2005 include two weeks on the Isle of Man, a week in Scotland, and a possible trip to Norway. Can't wait!

A technical thought also. A couple of years back, when ridden hard (80mph + crusing / hard acceleration), she was suffering from oil being blown out of the oil tank breather all over the rear tyre, etc. I was concerned the rings were shot (60,000 miles up by then on the originals), but could not understand why the oil was coming from the oil tank breather rather than the cylinder head cover breather. Eventually, I found that the cylinder head breather tube was completely blocked with emulsified oil, resulting in the crankcase having to "breath" back up the small bore tube from the crankcase rear to the oil tank separator, in turn pressurising the oil tank and forcing oil mist out of its breather. The solution was, and still is, to remove the cylinder head breather tube at every 3,000 mile service and clean through. Since then, no more oil loss (even at 100+), and the rings are still original at 82,000.
It would be interesting to know if any one else has suffered this problem (most people unfortunately probably do not cover enough miles on these bikes any more though). It may just be a feature of our climate here in the UK (rarely over 25°C even in the middle of Summer). Most of the time the engine does not run hot enough, even on long trips, to completely burn off all moisture in the oil. (there is usually some emulsified oil present under the oil tank cap.

I probably should of posted this tale to get some discussion going.

Cheers for now - Chris

NOTE: Chris, this is GREAT stuff ! ss


Somer

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Years ago I met a guy from Germany. He had a sandcast with 170,000 miles on it! He said Honda had tried to buy it off of him.


hondasan

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The old girl is presently at 118,000 miles and still running strong, but only averaging 4000 miles per year these days. I suspect (hope) it will outlive me.

Chris R.
Chris R.
302/338


rf065

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Mine also had oil from the breather hose onto the rear tyre. As a temporary measure I disconnected a breather at the top of the cylinder head and connected the oil breather hose on instead, at least then the oil was sent back into the engine. This was around 1978. I also met another CB750 owner a few years later stopped in a service station on the motorway in England with the same problem. He was stranded miles from home until we told him how we could swap the breather over allowing him to continue home.

Another problem I've never heard mentioned here which I believed was common to the CB750, was jumping out of 4th gear at high revs, apparently a problem with the gear selector drum?

Russ


sancastnorway

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I see that there is someone who think that a sandcast have high milage here. There is a man here in Norway who is 68, and bought his sandcast in 69. He has sold it 2 or 3 times, but always bought it back. He still ride it, and say he is a biker, not a "chrome polisher" He ride the bike summer and winter, and do a 700 km trip with only stop for filling gas and the on the road again.

His bike has in August 2012 gone 570.000 km, or about 350.000 miles.... he has replaced piston one time, and the primary chain and cam chain, the rest is still original.

His solution on the long milage: Replace oil every 3000km with castrol GTX

Jan


kp

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That's a great bit of information Jan. I think I'm on safe ground here when I say now ay a Harley would achieve half that without a total rebuild or two or three or four or five ;D (Sorry Wayne, I couldn't resist)  :-[
Yabba Dabba KP


Prospect

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I see that there is someone who think that a sandcast have high milage here. There is a man here in Norway who is 68, and bought his sandcast in 69. He has sold it 2 or 3 times, but always bought it back. He still ride it, and say he is a biker, not a "chrome polisher" He ride the bike summer and winter, and do a 700 km trip with only stop for filling gas and the on the road again.

His bike has in August 2012 gone 570.000 km, or about 350.000 miles.... he has replaced piston one time, and the primary chain and cam chain, the rest is still original.

His solution on the long milage: Replace oil every 3000km with castrol GTX

Jan

That's incredible!  I've heard of cb750's going close to 200,000 kms but not 570,000!  I'd love to see a picture of this machine. 
Vin 256/106


Wayne

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That's a great bit of information Jan. I think I'm on safe ground here when I say now ay a Harley would achieve half that without a total rebuild or two or three or four or five ;D (Sorry Wayne, I couldn't resist)  :-[

haha That's OK Steve. Us Harley riders have heard it all. Jan is correct though. Maintenance is the key. He's just using the wrong oil. If you REALLY want an engine to last you use Kendall GT and change it every 5000 KM. ;)
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Steve Swan

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Kendall is probably the best oil available.  Oh, oh.  Dreaded oil thread....   We ran Kendall R straight 30 weight in the R6 when we were road racing.  No wear areas anywhere on engine parts for around 45 races each season, at rpm's generally sustained between 9000 - 13,000 rpm.  Agreed Wayne.  Kendall is good stuff.