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 Post subject: Re: Flooded engine
PostPosted: Mon Feb 04, 2013 9:41 am 
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Joined: Mon Apr 03, 2006 12:00 am
Posts: 371
Location: Northampton UK
model: 907 I.E.
year: 1993
Isn't that what the breather tower in the later bikes held (the membrane)


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 Post subject: Re: Flooded engine
PostPosted: Mon Feb 04, 2013 10:43 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5360
Location: southern Germany
model: 750 Paso
year: 1987
yes. I thought it was the same on the Paso but I`ve just checked some pictures of my bike and noticed it`s different.

G.


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 Post subject: Re: Flooded engine
PostPosted: Mon Feb 04, 2013 11:18 am 
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Joined: Mon Apr 03, 2006 12:00 am
Posts: 371
Location: Northampton UK
model: 907 I.E.
year: 1993
I think from '91 it changed to be something a bit more useful ! :shock:


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 Post subject: Re: Flooded engine
PostPosted: Mon Feb 04, 2013 5:16 pm 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1322
Location: SF Bay Area
model: 750 Sport
year: 1990
The Paso and the Sport had the one way valve inline to the breather box, and the fitting on your engine was a straight through fitting. The old one way valve was big, and heavy, and I have only seen one of them. Using a later model breather valve will certainly help. The better place for the one way valve is on the outlet side of the breather box, which is where it is on some Ducati models, and some have moved it all the way to the air box. (749 I believe) I think the % of Pasos and Sports with the stock breather pipe, valve, breather box and assorted lines is in the low single digits.

G- Generally I agree that pollution control devices should be used when they do some good. But the gasses from the breather line are relatively caustic to your engine, and the amount of pollutants compared to the exhaust is is a very small number. I'll dig up an article or two that convinced me. While there is some unspent fuel in those gasses, more of it is moisture and caustic elements. Sending them back through the engine does not reduce them, it just shortens your engine life.

Cheers, Phil

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1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Flooded engine
PostPosted: Thu Mar 28, 2013 11:19 am 
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Joined: Mon May 10, 2010 9:49 pm
Posts: 359
Location: eu/us
model: 750 Paso
year: 1987
JWilliam wrote:
The petrol flooding is no big deal and it won't have allowed any great amount of fuel into the engine. Here is what happens - Switch off engine, carb is primed. Leave for a few months and the fuel evaporates out of the carb leaving a gummy residue that sticks the float valve open. Switch on ignition and the float valve won't close - flooding. The most you need do is dismantle the Weber and unstick the float valve. Of course this also suggests that when you next have a break from riding her you should remove fuel from the Weber.



Changed plugs, oil, and it started right up.

I have some doubts about shutting off the fuel flow.
Years past I always left the fuel on and never had a problem even after 6 months.

Last year I shut it off and added some fuel preservative and ran the bike a bit after shutting the fuel.
Four months later, it started but died and then flooded.

So, coincidence? I don't know, but it worked better with no special measures.


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 Post subject: Re: Flooded engine
PostPosted: Thu Mar 28, 2013 3:03 pm 
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Joined: Wed Sep 19, 2012 11:33 am
Posts: 75
Location: Taunton, England
model: 750 Sport
year: 1990
ducinthebay wrote:
The one i used was the Bunn Breather...
Cheers, Phil


Phil, I was curious about this as my bike has no breather box, just a hose leaving the crankcase led out to the back of the bike. I spoke to a guy here in the UK who markets the Bunn breather for Triumphs, and he explained it requires an inlet to take clean air into the engine in addition to the outlet, which is already there. I queried the inlet, and he said he just taps into the rocker cover on the Triumph motors he fixes it to, and advised I could do the same. However there is no connecting airway from the head of a 750 motor into the crankcase as far as I can see, so do you have any suggestions as to where a fresh-air inlet could be fitted into the crankcase if I were to buy and fit a Bunn breather?


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 Post subject: Re: Flooded engine
PostPosted: Thu Mar 28, 2013 3:21 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5360
Location: southern Germany
model: 750 Paso
year: 1987
I don`t get how any clean air could get into the engine as there`s overpressure when it`s running. The only air that gets into the engine would be what gets by the piston rings.

G.


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 Post subject: Re: Flooded engine
PostPosted: Thu Mar 28, 2013 6:47 pm 
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Joined: Wed Sep 19, 2012 11:33 am
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Location: Taunton, England
model: 750 Sport
year: 1990
paso750 wrote:
I don`t get how any clean air could get into the engine as there`s overpressure when it`s running. The only air that gets into the engine would be what gets by the piston rings.

G.


That's my point G - without a clean air inlet into the crankcase the Bunn breather (as I understand it at least) can't operate effectively.

I do like the sound of it though - supposed to let the engine rev more freely and prevent caustic chemicals building up in the crankcase.

Dan


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 Post subject: Re: Flooded engine
PostPosted: Thu Mar 28, 2013 10:22 pm 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1322
Location: SF Bay Area
model: 750 Sport
year: 1990
Yes, this is all true. And true of most all crankcase ventilation systems.
The ideal system is to have two one way valves that passes filtered fresh air through your engine, and keeps the crankcase pressure low.
However, the Ducati engine has no good inlet for fresh air to the crankcase. I have not found a solution to that yet. I only got half the way by putting on one of his valves on the end of my breather, and trying to make my breather box as large as possible. I'm basically making sure that I am running the engine in a negative pressure situation.

There are some discussion on Ducati.MS, but none have come up with a good fresh air inlet.

Not a complete solution, but the start of a better one.

Cheers, Phil

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Flooded engine
PostPosted: Thu Mar 28, 2013 11:23 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3209
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
Lots of opinions in this thread,not much fact..............

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Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie


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 Post subject: Re: Flooded engine
PostPosted: Fri Mar 29, 2013 1:39 am 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1322
Location: SF Bay Area
model: 750 Sport
year: 1990
Higgy, its so unlike you to throw stones.
Here is an article that I first read, then I searched some more on the web. Lots of stuff out there once you start looking.
http://bunnbreather.bigblog.com.au/index.do
The fact that Moto GP, Nascar, F1 and other motorsports spend time and money to evacuate the crankcases tells me that there is some science behind it. However you look at it, you have to admit that the blow by from your pistons is not a mixture of chemicals that you want to accumulate in your oil. I think the open question is if a short breather with filter on it is as good as a more complex system with one way valves?

I have not found a full solution to this problem, and admittedly, its a minor problem that requires some engineering. The returns are minimal. Changing your oil often will do just as good.

Cheers, Phil

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Flooded engine
PostPosted: Fri Mar 29, 2013 11:03 am 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3209
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
Oh Contraire, I have a bypass filter on my truck just to address blowby. Currently have over 2000 hours on my oil.
And G will tell ya I've been know to chuck a rock now and then just for S&G :lol: :lol: :lol:


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_________________
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie


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