Wildguzzi.com
General Category => General Discussion => Topic started by: stuv65 on September 09, 2015, 07:19:19 AM
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Some time ago I posted that I was going to do away with the sump oil return pipe, breather box, air filter, etc on my V65 and just run a hose from each rocker cover. I routed these 2 hoses into the tool box (there were two holes in the bottom that I sealed with silicon). Not an original idea, but I wanted to try it.
The result - a slight mist of oil in the tool box (and a dead fly).
So as far as my bike is concerned, very little oil (vapour) lost. On the up side - a few less hoses cluttering up the bike and more room behind the headstock for wiring.
A word of caution - if you follow the same set up please check your engine oil level frequently - just in case it doesn't work on your bike.
ta
stuart
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I suspect with time you will get a fair amount of oil collecting in your toolbox. As long as you don't mind...
What did you do with the return hose to sump?
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I was hanging out a MGC in SoCal last time out when a guy brought in a small block that that been built by a respected engine builder. He had the same type of setup, and after maybe 50 miles on the interstate at 80 the catch can was overflowing and dumping oil on his rear tire.
YMMV, but...
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From Rod Yeomans, RIP
Small block guys.. ignore this at your own risk.. I had a breather line come loose on the Lario during a hard run, and there was oil *everywhere*..
Engine breather system
Many of the bikes have had their original filter boxes removed and pod filters fitted to replace them. What a lot of owners don't understand is the breather system that is connected to the filter box.
The purpose of the breather system is to return oil condensate to the sump. Without this a Guzzi engine would eventually pump itself dry of oil. The engine has a shared journal crank so even though the pistons are 90° apart there is still a constantly changing volume under the pistons in the crank case as the engine turns. The volume under the pistons changes by about 70% of the engines displacement every revolution.
Oil ridge and fangs.
Oil ridge and fangs.
Photo courtesy of Rod Yeomans.
Early bikes only had a very small oil dowel (1 mm) feeding oil to the valve gear. The rest was supplied by the breather system. Oil vapour was carried up via the push rod ports to condensate on the inside of the rocker covers. This would then drain down to a ridge in the casting and there are 2 fangs that sit directly above the valves and direct the oil to fall on them. Moto Morinis of the same era used this system solely to lubricate the valve gear. On later small blocks the oil dowel was increased (3 mm) and the main oil feed is via that but the vapour system still works as long as the breather system is intact enough. Larger oil dowels were fitted from engine numbers: V35 / 24550, V50 / 25180, V65 / 1162. It is recommended that this modification is undertaken on earlier engines.
If the breather system is blocked off or restricted then the crankcase builds up pressure. This may cause the engine to leak from any of its joins and seals. At low speeds the breather will suck air in too as the pistons rise so it is a good idea to have the breather vent filtered. It originally vented into the clean, negative pressure side of the filter box. It makes me wonder if the removal or modification of the original systems and the subsequent reduction in oil condensate flow to the top end contributed to a shorter service life for the valves.
It should be noted that the breather flow is the reverse in a small block to a big block engine. The small block flows in parallel with thermal effect up the barrels and out the rocker breathers. The oil returns directly to the rear of the sump below the oil level, so it acts as a one way valve.
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I blanked offf the sump return pipe with a crush (aluminium) washer and suitably sized bolt.
I agree changing the engine breather system could lead to problems - I'm watching the engine oil level closely.
ta
stuart
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I have used a big block tin breather box mounted right behind the steering head. It takes some fiddling but can be mounted out of the way of everything else. I made the two head breather tubes merge into one right angle elbow into what I guess would be the vertical crankcase breather on a big block. The return line goes to the sump.
Distance I have used this- 40,000+ kms.
Oil issues - nil.
Even with converting to the bigger engine I kept the same system since it was a. there on the Monza frame already and b. proven to work. Again, nil issues.
The tin box is a LeMans unit or similar.
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When I put 30mm PHF's on our V65C, I used those stinking pod filters and made my own breather by brazing a tuna can to a plate- Guzzi content- as Chuck would say, with the appropriate tubes for air/oil separation. The hose routing remains the same. Deb has kept up to me , mostly, on trips to Texas and western Montana where she ran that little bugger hard for days on end. I think it has over 30K miles on it with no loss of oil so I think it was a success.