Flooded engine

[plasmid]

Happy New Year everyone.


Tried to start my Paso today - sat for 3 months. It's got the stock Weber.

Started briefly then died. Then took a while to start
and it was running on one cylinder.

Pool of gas underneath, blown through both exhausts.

Would you guys change the oil if gas got it in there?

In prior years I always stored it with the gas petcock on and never had a problem,
even after 6 months.

Now I turned it off and bam.

[Truten]

If gas is in engine oil you MUST change it. When gas goes into the oil you have very poor lubrication and you are close to make your engine useless. So change the oil and filter.

[plasmid]

If gas is in engine oil you MUST change it. When gas goes into the oil you have very poor lubrication and you are close to make your engine useless. So change the oil and filter.

On an oil forum the consensus was that if it's not that much it evaporates.
But I agree that it's safer to change it.

[Truten]

On an oil forum the consensus was that if it's not that much it evaporates.

Hi plasmid,
I assumed that you have plenty of petrol in your engine oil that you can see that oil level changed...

There is always a bit of petrol in oil when you use your bike, becasuse a bit of petrol-air mixture are not completely burned and some small amount of petrol flowing down the cylinder surface and goes to the oil. That small amount is acceptable.

[ducinthebay]

One of the reasons to have good positive crankcase ventilation with a a one way valve on the breather pipe.

Cheers, Phil

[delagem]

One of the reasons to have good positive crankcase ventilation with a a one way valve on the breather pipe.

Cheers, Phil

Is this normally how the gas gets into the motor on a Paso? My Paso doesn't have an air box (Dellorto conversion) so I don't know.

I have this problem on another bike, but the gas definitely overflows the carb bowl, and goes down the intake and into the cylinder. Most gas winds up in the exhaust, but some makes its way past the rings and into the gas. (no air box, just a pod filter on the carb).

Definitely change your float needle, that's what's letting the carbs overflow in the first place....

[ducinthebay]

By putting a one way valve on the crankase breather, you ensure that the fumes and bad gasses of blow by actually go out of the crankcase instead of just staying in there. If its just a tube with a filter on it, you are pulling and pushing air through the hose, but never really ensuring that anything is leaving the cases. Blow by is the main reason to change your oil regularly, as it absorbs the acids and nasty stuff from combustion and will make your oil acidic. Positive crankcase ventilation helps to remove those gasses before they get absorbed by the oil. It also helps get the moisture out, which Ducati engines seem to be prone to. Every see milky oil in your view window? Inadequate ventilation, and/or you don't go for long enough rides.

The gasoline (petrol) in your crankcases is most certainly from your carb overflowing.

Cheers, Phil

[randtcastell]

Hey Phil: Can you suggest where I might be able to source a one way valve that would be appropriate for my crankcase breather tube? Thanks. go 49ers!

[ducinthebay]

Randy,
The best thing is to keep the stock overflow tank, as it adds volume to your crankcase basically. Bigger volume is easier to keep a negative pressure, which is what you are aiming for. However, on the outlet side of it, that used to go to your air box (by law), you put on a one way valve and vent it to atmosphere. Don't really want to send those nasty gasses back into your engine.

Some have put on a PCV unit from a car, but they usually aren't sturdy enough, or act fast enough for a two cylinder motorcycle. Think of the pumping action of a 4,6 or 8 cylinder compared to a two cylinder bike. Even a four cylinder engine usually has one piston going down when one is going up, so there aren't big pulses of pressure like in a Ducati engine. Of course the worst is a BMW twin, followed closely by a big single.

The one i used was the Bunn Breather.
http://www.bunn.co.nz
Not a very professional site, but from what I can find on the web, he's about the only guy concerned with such things, and making something for bikes in particular. He has the science behind it, which is more than I can say for most products.

I do not have the stock overflow tank on my bike, as it doesn't fit with the shock I have. I adapted a stiff 1.5 tube that runs to the back of the bike, and put the Bunn Breather in the end of that near the tail light. I want to make a better breather box that has a catch section in it that I can drain. I think fiberglass is in my future. I do notice a slight performance improvement, but its hard to quantify.

Cheers, Phil

[JWilliam]

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.

[ducinthebay]

yeah, a little Sea Foam fuel additive before its winter nap will help too.

The method an old biker down the block always used:
He would pull into his drive way, turn off the petcock, but leave the bike running, open the garage door, pull in, rev it up a couple of times, then turn it off. Besides making a wonderful noise for all the neighbor boys to envy, he was emptying his float bowls before parking the bike. Did it every time. Pissed off my mom, but we loved the noise, and he later dated my sister. Maybe that's why mom didn't like him.

I on the other hand, have taken out the fuel petcock on my Sport, as the bike has a pump in it. I replaced the petcock with a large banjo fitting and run it straight to the carbs. I have the Dellortos, but that should not be that much different. Not a problem in 5 years.

I have been toying with adding a vacuum operated fuel shut off that comes stock on some Monsters. Cheap on e-bay.

Cheers, Phil

[randtcastell]

"The one i used was the Bunn Breather."

Thanks Phil for the knowledge and the link you've shared. Big help! My Paso came with a breather tube and a small K&N filter the end. I'd like to improve on that soon.

[plasmid]

yeah, a little Sea Foam fuel additive before its winter nap will help too.

The method an old biker down the block always used:
He would pull into his drive way, turn off the petcock, but leave the bike running, open the garage door, pull in, rev it up a couple of times, then turn it off. Besides making a wonderful noise for all the neighbor boys to envy, he was emptying his float bowls before parking the bike. Did it every time. Pissed off my mom, but we loved the noise, and he later dated my sister. Maybe that's why mom didn't like him.

I'll spare you the carb metaphors.

I on the other hand, have taken out the fuel petcock on my Sport, as the bike has a pump in it. I replaced the petcock with a large banjo fitting and run it straight to the carbs. I have the Dellortos, but that should not be that much different. Not a problem in 5 years.

I always left mine open, no additives. No problems, with as long as 6 months storage.

This year I closed it and added some Liqui-Molly fuel additive.

Perhaps coincidence, but I won't be doing that again.

[plasmid]

On an oil forum the consensus was that if it's not that much it evaporates.

Hi plasmid,
I assumed that you have plenty of petrol in your engine oil that you can see that oil level changed...

There is always a bit of petrol in oil when you use your bike, becasuse a bit of petrol-air mixture are not completely burned and some small amount of petrol flowing down the cylinder surface and goes to the oil. That small amount is acceptable.

Plugs are toast. Oil level the same. Good viscosity, bit of a gas smell.
I'll change it in spring.

Had a Paso once that had the Dell Orto's and it fouled one of the plugs quite regularly.
But I never had gas spewing out of the exhaust on carb bikes or cars.

Don't want to bad mouth the Liqui-Molly fuel stabilizer but
I won't be using it again.

[paso750]

Phil, I`m wondering about all this. Doesn`t the original crankcase output have a membrane (reed valve) in it ? I always thought so but I never removed or opened one.

However, on the outlet side of it, that used to go to your air box (by law), you put on a one way valve and vent it to atmosphere. Don't really want to send those nasty gasses back into your engine.

I disagree on that. I`m not a tree hugger but imo the environmental aspect has more weight than not wanting crankcase gases to be recycled for whatever reason.

G.

edit: just found this photo. The standard Ducati crankcase breather (which does look different to what is on my engine)