Gasoline within Oil / Gasoline Pipe questions

discussions specific to the 906 Paso
Post Reply
pasoalf
Posts: 72
Joined: Tue Feb 03, 2009 9:44 pm
model: 750 Paso
year: 1987
Location: Switzerland

Gasoline within Oil / Gasoline Pipe questions

Post by pasoalf »

I took my paso906 on Friday out to do a big maintenance (change belts, cooling fluid, all other oil fluids, and filters, check torque on cylinder nuts ect.). Bought the 906 2 years ago, made 1000km (now 29’000). I decided to do so because I have no service history. When I tried do Star it (to warm up for changing oil) it became to much Gasoline. Later on I could start it without problems.
Doing maintenance I realized 3 things

• Doing maintenance on a 906 is much more time consuming than on a 750
• There was quite a lot oil coming off (more than 3.5 l, which had a strong gasoline smell)
• I found a kind of selfmade reduction on the waste fuel rubber pipe wich is connected to the underside of the fuel tank.

First of all has anybody an idea how the Gasoline has come into the oil? I did checked the floater. It seems that it closes just when the floater is on the most up possible position. How can I check easily weather the valve really closes? , resp. is there an easy way to find the correct position? ( On the other hand I don’t want to change much because the 906 runs marvellous)
Image


Concerning the selfmade reduction on the waste fuel rubber pipe, has anybody a clue what this is for ? (perhaps to increase fuel pressure??)
Image

Any good hints are welcome,
regards pasoalf
Paso 750/ 1987
Paso 906/ 1992
User avatar
bmw851
Posts: 322
Joined: Tue Mar 13, 2012 9:02 am
model: other
year: 1988
Location: The Blue Mountains, NSW, Australia

Re: Gasoline within Oil / Gasoline Pipe questions

Post by bmw851 »

Hi Pasoalf,

Fuel in the oil is usually because the carb is flooding or over filling to use another term, the float action on/off may seem ok, but the float needle could be sticking open under fuel pump pressure, 1st thing is to clean everything reassemble and try again, I once drained 5 litres out off my 750 sport engine through the float needles sticking on, and fuel pumping past the inlet valves and into the crankcase's, it certainly gave it a good clean out :lol: I knew straight away what the problem was and simply replaced the float needles and problem was fixed, but this was on Keihin FCR's, the webber may be more complicated.

good luck with it

Cheers

Peter
So long, and thanks for all the fish...............

https://www.facebook.com/PDBCustomGuitars
User avatar
higgy
paso grand pooh-bah
Posts: 3334
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Re: Gasoline within Oil / Gasoline Pipe questions

Post by higgy »

The weber is no more complicated you need a new needle and seat and check the float level.
Alfa 1750 has an ebay store and is cheaper than almost everyone else

ALFA1750'S CARBURETORS PARTS STORE
http://stores.ebay.com/ALFA1750S-CARBUR ... ORE?_rdc=1


you will need to drain the cases and change your oil once you have the carb sorted out :thumbup:

The restriction was an attempt to control fuel pressure issues found on some bikes after the exhaust had been changed
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
User avatar
JWilliam
Posts: 331
Joined: Wed Oct 06, 2004 12:00 am
model: 906 Paso
year: 1989
Location: Nottingham, UK

Re: Gasoline within Oil / Gasoline Pipe questions

Post by JWilliam »

Float level is too high. Bend up the tab until the float is parallel to the above carb plate. The jet within the fuel line is to maintain fuel pressure. You might as well leave it in.
User avatar
bmw851
Posts: 322
Joined: Tue Mar 13, 2012 9:02 am
model: other
year: 1988
Location: The Blue Mountains, NSW, Australia

Re: Gasoline within Oil / Gasoline Pipe questions

Post by bmw851 »

Personally I'd take Higgy's advice and replace the needle and seat just as a matter of precaution as they are most likely the originals and would be due anyway, (sorry forgot to write the needle & seat, thanks Higgy :thumbup: ).

Also wouldn't hurt to remove the screw in plug (17) on the front cylinders header pipe as well, when this happens they can fill with fuel as well I again know this from personal experience.

Currently playing with a 1988 BMW R100RS that had been in storage for 5 years, and finding all sorts of interesting things to do to the carbs on that. :lol:

Cheers

Peter
Attachments
Plug.JPG
Plug.JPG (52.35 KiB) Viewed 11826 times
So long, and thanks for all the fish...............

https://www.facebook.com/PDBCustomGuitars
User avatar
higgy
paso grand pooh-bah
Posts: 3334
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Re: Gasoline within Oil / Gasoline Pipe questions

Post by higgy »

you don't need the jet in the return line at all and most likely it is the source of your bad needle and seat. The standard pump has too much pressure and restricting the return line will only make it worse.The proper placement of a restriction jet is in the vacuum line that goes to the control unit on the 906( well sort of anyway).You may even find taking the restriction out of the return line might solve your needle and seat leaking issues if it is not too late.
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
fester
Posts: 66
Joined: Tue Dec 03, 2013 7:41 am
model: 900 SS
year: 1989
Location: Gympie Qld Australia

Re: Gasoline within Oil / Gasoline Pipe questions

Post by fester »

I thought the restrictor went in the fuel feed after the "y" splitter to actually reduce the flow to the carb.
Mc tool
paso grand pooh-bah
Posts: 1883
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: New Zealand

Re: Gasoline within Oil / Gasoline Pipe questions

Post by Mc tool »

As Higgy sez ( sort of ) better off without it . I have the Y as close to the carb as reasonably possible and have the return line ( 1/4" ) dawdling from the carb to the tank . The resistance of the return line alone is enough to see a reasonably pressure at the carb . Some people fitted a restrictor ( jet ) in the return line , probly trying to increase fuel pressure to sort the carb issues , human nature ..... if a little fuel pressure is good then more has got to be better :banghead:
I wish I was young again............Id be heaps smarter than last time
pasoalf
Posts: 72
Joined: Tue Feb 03, 2009 9:44 pm
model: 750 Paso
year: 1987
Location: Switzerland

Re: Gasoline within Oil / Gasoline Pipe questions

Post by pasoalf »

Thanks for the inputs. For the time being I'll leave the reduction within the pipe, and I'll control the oil level frequently....
I'm a bit afraid change anything, because the 906 is actually running perfect.!!!
But I'm going to order a fuel pressure gauge. I've seen one for 33 euro with all fittings on.
Has anybody an idea what the fuel pressure of a 906 should be?
Paso 750/ 1987
Paso 906/ 1992
Mc tool
paso grand pooh-bah
Posts: 1883
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: New Zealand

Re: Gasoline within Oil / Gasoline Pipe questions

Post by Mc tool »

3-4 psi .
for some reason the float valve is not controlling the float level . More than likely this will not be evident when the bike is running ( you say it runs well ) . What is most likely happening is that when the bike is not running , and has FULL fuel tank , gravity is causing fuel to flow thru this leaking float valve , over fill the carb float bowl and then run into the inlet manifold , down thru the inlet valve , past the rings and into the sump . Its all very well to monitor the oil level but any fuel that gets into the oil will dilute it . If you remove some oil to get the correct oil level , when the engine heats up the fuel will evaporate leaving you with a low oil level , and fuel diluted oil will not lube the engine properly. I have seen a similar case where when the fuel started to evaporate out of the engine oil, the fuel vapour went thru the crankcase breather and into the air box and the resulting mix that made it to the engine was so rich it would hardly run until the excess fuel had boiled off . The bike would start and run ok till it started to warm up , then it got worse and worse ... hardly rideable .... then it slowly came right , until the next time the owner parked it up for a week.
Put a new float valve in it :)
I wish I was young again............Id be heaps smarter than last time
pasoalf
Posts: 72
Joined: Tue Feb 03, 2009 9:44 pm
model: 750 Paso
year: 1987
Location: Switzerland

Re: Gasoline within Oil / Gasoline Pipe questions

Post by pasoalf »

I now took of the restriction inside the return line, and replaced the Oil. No difference, the bike still runs well. But when i Take of the Oil filling Screw, ther is still a strong gasoline smell (don't know if this is from before...) I also saw on the oil inspection cap, some white creamy fluid above the oil (just a little bit) I Really don't know if this is because of gasoline within the oil...? The Oil Level is still O.K. (did not increase) anyway, I'm just going zo order a new needle valve, and i closed the fuel cock, just to avoid....
Concerning needle valve, i did not find any under the Ducati No (037027010). But i found a Weber specialist in Germay, which is well sorted with parts. But it seems that there exist different diameters. Has any of you an Idea which is the correct one???

Diameter 1,25mm Bestell.Nr. 8800 Weber OriginalpartNo: 79405125-79501125
Durchmesser 1,50mm Bestell.Nr. 8803 Weber Originalnummer: 79501150-79405150
Durchmesser 1,75mm Bestell.Nr. 8805 Weber Originalnummer: 79501175-79405175
Durchmesser 2,00mm Bestell.Nr. 8807 Weber Originalnummer: 79503200
Durchmesser 2,25mm Bestell.Nr. 8809 Weber Originalnummer: 79503225
Durchmesser 2,50mm Bestell.Nr. 8808 Weber Originalnummer: 79503250
Durchmesser 3,00mm Bestell.Nr. 8819 Weber Originalnummer: 79503300
Paso 750/ 1987
Paso 906/ 1992
Mc tool
paso grand pooh-bah
Posts: 1883
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: New Zealand

Re: Gasoline within Oil / Gasoline Pipe questions

Post by Mc tool »

The white creamy stuff is because the oil is not getting hot enough to boil out moisture , short runs , cold weather , I wouldn't loose sleep over it :)
I wish I was young again............Id be heaps smarter than last time
User avatar
higgy
paso grand pooh-bah
Posts: 3334
Joined: Tue Jul 29, 2008 9:50 pm
model: 907 I.E.
year: 1992
Location: Hilltown,Pennsylvania
Contact:

Re: Gasoline within Oil / Gasoline Pipe questions

Post by higgy »

replace the needle and seat with the 79503.xxx where xxx is the size marked on the current jet size, the one you have should have its size marked on it. Can't read it any more go with a 79503.300
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
jayh
Posts: 247
Joined: Thu Oct 22, 2009 10:38 am
model: 750 Paso
year: 1986
Location: Mildura ,Australia

Re: Gasoline within Oil / Gasoline Pipe questions

Post by jayh »

Simple test Alf. Take your air cleaner off and look inside the carby with the engine off but the fuel pump running (ignition on).If the carby is flooding,you will see fuel dripping from the centre of either venturi.
You may need a torch to see clearly.This is the first place it starts dripping from if the float is set too high or your needle and seat are faulty.It may even do this without the fuel pump running or only when parked on side stand.

It makes sense to me that the float may be set a little high as my 750 runs best,when the float is on the high side,but it too risky running much above the recommended setting because of fire danger. J.
Post Reply