Flooded engine

[Duc750]

Isn't that what the breather tower in the later bikes held (the membrane)

[paso750]

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.

[Duc750]

I think from '91 it changed to be something a bit more useful !

[ducinthebay]

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

[plasmid]

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.

[Danielmc]

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?

[paso750]

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.

[Danielmc]

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

[ducinthebay]

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

[higgy]

Lots of opinions in this thread,not much fact..............

[ducinthebay]

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

[higgy]

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