A: Oil Pipework Oil consumption

Nigel Spaxman

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LoneStar

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I found Nigel's dissertation very convincing, so adopted his ideas during my recent rebuild. I also replaced the banjo bolt with a L-fitting, for greater cross-section, and use thin-wall black tubing from there (c. 1/2" ID).

Good results, not perfect. A few drops of oil escape from the tube when idling or parking after a ride, but very little. No accumulation towards the rear of the bike, and very little overall oil loss.
 

Nigel Spaxman

Well Known and Active Forum User
VOC Member
I found Nigel's dissertation very convincing, so adopted his ideas during my recent rebuild. I also replaced the banjo bolt with a L-fitting, for greater cross-section, and use thin-wall black tubing from there (c. 1/2" ID).

Good results, not perfect. A few drops of oil escape from the tube when idling or parking after a ride, but very little. No accumulation towards the rear of the bike, and very little overall oil loss.
I use the standard Banjo bolt but I drilled it out a bit, and I marked it to make sure the hole is always lined up with the tube. I have a 3/8" tube, a pretty standard one going under the engine, a hose going back to near the swing arm, and then a tube attached to the brake stay. Not much leaks out. I am glad to hear that some other people read about my method that and are using it. A lot of people just can't get past the idea that the valve has to be open only when the pistons are coming down. It has more to due with the crankcase volume than what direction the pistons are moving. The standard timing closes the valve right at the exact time when it should remain open for a bit longer.
 

robin stafford

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I have checked the engine oil no smell of petrol so I dont think the bores are glazed the compression is very good can stand on kick start with both cylinders. will using mk two cams increase the oil consumption with short guides. I have got an elephant trunk breather may try to see what happens but I dont like the look of them . What is the theory of using thicker oil it take longer to reach the cam gear. 5000 miles I have only adjusted the valve gear once on the front exhaust Have done oil temp checks in the summer after a 100 mile run at 60/80 mph the most recorded was 36 c so a thicker oil will never come up to its working temp
 

LoneStar

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VOC Member
I use the standard Banjo bolt but I drilled it out a bit, and I marked it to make sure the hole is always lined up with the tube. I have a 3/8" tube, a pretty standard one going under the engine, a hose going back to near the swing arm, and then a tube attached to the brake stay. Not much leaks out. I am glad to hear that some other people read about my method that and are using it. A lot of people just can't get past the idea that the valve has to be open only when the pistons are coming down. It has more to due with the crankcase volume than what direction the pistons are moving. The standard timing closes the valve right at the exact time when it should remain open for a bit longer.
FWIW, here are the measurements I took of my stock breather installation. Cross-sectional area at various points, in square inches:

1. slot in breather collar - .252
2. slot in breather spindle - .179
3. breather spindle bore - .085
4. bore, banjo bolt - .054
5. side holes (4) in banjo bolt, total - .076
6. annular gap between banjo bolt and ring - .085
7. output pipe from banjo ring - .041
 

bmetcalf

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I have checked the engine oil no smell of petrol so I dont think the bores are glazed the compression is very good can stand on kick start with both cylinders. will using mk two cams increase the oil consumption with short guides. I have got an elephant trunk breather may try to see what happens but I dont like the look of them . What is the theory of using thicker oil it take longer to reach the cam gear. 5000 miles I have only adjusted the valve gear once on the front exhaust Have done oil temp checks in the summer after a 100 mile run at 60/80 mph the most recorded was 36 c so a thicker oil will never come up to its working temp
ClevTrev has reported low temperatures after a longer run. I can’t remember what weight he recommends, but it seems logical to experiment and get the temp up to 180F by using lighter oils.
 

LoneStar

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VOC Member
ClevTrev has reported low temperatures after a longer run. I can’t remember what weight he recommends, but it seems logical to experiment and get the temp up to 180F by using lighter oils.
Apologies if this is obvious or universally understood - but why would a lower viscosity oil run hotter, other factors being equal?
 
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