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LM1 Breather Problem

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GuzziPaul View Drop Down
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    Posted: 02 Apr 2016 at 18:09
Got my Le Mans started today, possibly the first time it has run since 2002. Ran it for about five on the centre stand and then put it on the side stand.
Lots of oil came out of the breather.
Is it possible the return valve into the crankcase is stuck?
I've abandoned the returns from the heads assuming the oil from the heads will return down the pushrod tubes, so not sure where the oil is coming from.

The generator light is also staying on, any clues as what this could be?
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 02 Apr 2016 at 18:35
Could be that the oil return from the breather box is blocked and you're getting a build up of oil in the box which escapes down the pipe to atmosphere.
The returns from the heads aren't oil returns but vent pipes to reduce crank case pressure and to prevent condensation in the rocker boxes.
Charging light.Could be one of several things.Look at the alternator where the three hard wires from the stator join the connector block ..I've twice had a dry joint there on Tonti's.Drops a phase and leaves the light on.
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dan_s View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dan_s Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 09:45
Things to consider, overfill of oil, perished piston rings.
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Asjc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Asjc Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 10:12
Re the charging light, sometimes where the bush's rub on the copper rotor surfaces can do with a liitle very light wet and dry to make a good contact.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 13:14
If the bike has not been run since 2002, then it's possible (assuming the Bosch alternator) that the rotor has lost its residual magnetism. Yu get round that by "flashing" it, put 12v across it for a second or so making sure you connect the negative to the earth side on the rotor.
But clean the slip rings first and make sure the brushes are in good contact with said slip rings.
Brian.

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italianmotor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote italianmotor Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 14:34
The Le Mans breather boxes can rust from the inside out - I've had a couple that needed repair because the condensation sits there, sounds like yours may be a bit stuck. Good thing to do too, as I have done on my 750 S3, is follow the guide in Guzziology, and disable the flapper valve in the breather box with a screw driver. Once done, buy and add the later ballcheck valve and add to the large breather pipe that connects the breather box to he crankcases. I did this and have never suffered from oil being chucked out of the breather pipe after long high speed runs as I used to, worthwhile mod.

Gutsibits Crankcase Breather Valve
ENA28560




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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 15:04
If you carry out the above mod' be sure to soak the catch can/breather box in solvent for a day or so.If the oil return tube to the crank case is blocked then changing the valve alone will have little or no effect.Whilst the can is soaking check that the rubber hose which connects to the oil return pipe in the crank case and the metal pipe itself are clear.This return route can bung up with rust particles and emulsified oil.
I'd also reconnect your rocker box breathers if I were you.By removing them you have diminished the ability of the crank cases to vent which will be further diminished by fitting the ball valve which has a smaller vent hole than the original setup.
Just my opinion.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

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italianmotor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote italianmotor Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 15:19
Yes, good advice, I also blew through mine witha an air line after spraying liberally inside with WD40 to make sure any crap had gone.
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lemon View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lemon Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 15:31

The generator light is also staying on, any clues as what this could be?
[/QUOTE]

I bought my first Guzzi super cheap because it wasn't charging. I cleaned the battery terminals and earth, sorted. Some time it's the simple things...
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 15:37
Twenty six years ago whilst using an 850T for my courier job with DELTA DISPATCH (remember them?)doing lots of motorway work at fairly high speeds my oil consumption rose to such a degree I used to carry a few pints of Castrol GTX and a funnel in my panniers.
After much head scratching and much replenishing of oil in motorway service areas I checked through the breather system.The oil return from the breather box was completely blocked and the hose was thickly coated with mayo'.After cleaning the system, and the rear of the bike!!!
oil consumption dropped to more normal levels.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dan_s Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 16:34
Does it charge? measure the voltage on the battery when revving it a bit. Voltage should rise above ~13.5v.
If it doesn't charge, check all components for continuity, shortcircuits and earth connections
Here is the best schematics for Bosch charging system: http://motortouring.nl/techniek/startenladen/charger.html
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GuzziPaul View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GuzziPaul Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 17:17
Thanks for all the replies and advice, there was certainly a lot of dried crap in the breather box when took it off to clean initially and any valve in there will certaily by stuck I guess. I'm just a bit concerned how much oil got in there so quickly.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2016 at 19:30
if you look in general electrical issues pg2 there is an easy guide how to check bosch charging systems , IF you need replacement parts call Paul Alen Electrics Marine he can get  variable electronic volts reg that is a plug in fit and new Bosch rectifier but theses rarely fail the how to check is an easy guide will save ££'s in farting about
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Dukedesmo Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2016 at 10:50
With regards to the breather, even if fully functional I reckon the breather box is too small. In the few miles I did on mine before it had a valve/piston mishap a little oil blew out the overflow and the box is in perfect condition.
Part of my rebuild included improving the breather system, especially because now with +5mm bigger pistons I expect the situation to be potentially worse.
 
I looked at making a new box but in the end went for the Agostini large box because it fits in nicely and looks 'right' however it doesn't have a valve in it. I saw the Gutsibits valve as above but don't like the fact that it's so small and can see it being overwhelmed if the engine starts pumping too much oil.
 
As a long-time Ducati owner I see how they do the breather thing and consider it a much better way, after all the engine configuration is virtually the same and with higher revs they do generate a lot of crankcase pressure and can spew a fair bit of oil.
 
I took a Ducati crankcase reed valve which is a much larger and faster acting valve than the Guzzi jobbie and modified it, using another valve to get a hose-to-hose fitting rather than a screw into the cases setup (much like Ducati used on race bikes) and plumbed that into the system.
 
Required moving and slight modding of the Agostini box but I now have a larger box with a larger one-way valve which I'm hoping will prevent any future blow-by issues.
 
 
 
 
 
Excuse the blue return hose, but I had it in the worshop and it's fluoro-lined silicone so good for oil, besides you can barely see it once the tank's fitted.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 06 Apr 2016 at 02:11
The purpose of the (ball) valve is to encourage oil to be scavenged out of the rocker boxes when the pistons rise, by it being sucked down the pushrod tubes (correct who wrote that) but also there's a drain tunnel as well down each barrel. This action also generates a slight vacuum in the crankcase this helps the breather box to drain back to sump via its drain tube and also helps the engine oil seals keep the oil in. However I've always had the opinion that the ball valve can't work fast enough at high rpms.
"Chicken nuggets don't dance on a Tuesday."
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