Author Topic: Very odd oil leak  (Read 1145 times)

Offline SteveW

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Very odd oil leak
« on: April 18, 2020, 03:18:32 PM »
Obviously haven't used the 550 for the last few weeks.
When I last rode her I turned the fuel tap off about 1/4 mile from home so the carbs are empty just as I get home.
In the garage on the center stand there is no sign of leaks. I took the bike out the garage the other day and left it on its side stand for a few hours, as I needed the space in the garage to rebuild a 1963 Vespa engine.

Came to put the 550 back in the garage and noticed there is a tiny trickle of oil running down the left hand side of the engine, down the middle of the cover that covers the front sprocket. Had a look and can see that the oil is dripping down from the bottom of #1 carb float bowl. The outside of the float bowl is covered in it?????

Its definitely oil, no smell of petrol and the carbs are empty of fuel anyway. I cleaned it up, put it on the centre stand, checked yesterday and no oil leak, only does it on side stand.

Any ideas? Bike runs fine by the way.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline Nurse Julie

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Re: Very odd oil leak
« Reply #1 on: April 18, 2020, 03:38:08 PM »
That's one of those 'Anti gravity side stand oil leaks' 😁😁😁😁How bloody peculiar. Its not a loose tappet cap is it, that's the only thing higher than carb #1 which is in a vertical line with the sprocket cover below? Or is it the cam end cap leaking and tracking , they are very prone.
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Offline sye

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Re: Very odd oil leak
« Reply #2 on: April 18, 2020, 03:41:52 PM »
Could it be a little oil draining from the airbox?

Offline SteveW

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Re: Very odd oil leak
« Reply #3 on: April 18, 2020, 03:52:38 PM »
Could it be a little oil draining from the airbox?

The breather pipe is not connected to the air box at the moment.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline SteveW

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Re: Very odd oil leak
« Reply #4 on: April 18, 2020, 03:54:46 PM »
That's one of those 'Anti gravity side stand oil leaks' 😁😁😁😁How bloody peculiar. Its not a loose tappet cap is it, that's the only thing higher than carb #1 which is in a vertical line with the sprocket cover below? Or is it the cam end cap leaking and tracking , they are very prone.

Tappet caps and cam cover are bone dry.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline Nurse Julie

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Re: Very odd oil leak
« Reply #5 on: April 18, 2020, 04:40:31 PM »
Could it be a little oil draining from the airbox?

The breather pipe is not connected to the air box at the moment.
Is the Breather pipe fitted to the Breather cover on the top of the engine?. I think the outlet pipe is on the right side of the cover though, not the left, so still wouldn't explain how the oil got down the near side though and there shouldn't be any significant amount of oil up in the Breather cover anyway. Aren't leaks a pain 🙄🙄🙄🙄🙄
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Offline SteveW

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Re: Very odd oil leak
« Reply #6 on: April 18, 2020, 04:50:05 PM »
Breather pipe is connected at the top of the engine.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline Woodside

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Re: Very odd oil leak
« Reply #7 on: April 18, 2020, 04:53:08 PM »
Is the breather pipe split

Offline SteveW

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Re: Very odd oil leak
« Reply #8 on: April 18, 2020, 05:10:42 PM »
Breather pipe is fine.

This possibly sounds far fetched, but could oil get past the valve stem oil seals. Then down the valve and back all the way into the carb bowl. Then leaking out of the carb bowl seal?

The rest of the carb is clean, it’s just the bowl that has oil on it.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline Nurse Julie

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Re: Very odd oil leak
« Reply #9 on: April 18, 2020, 05:20:07 PM »
Breather pipe is fine.

This possibly sounds far fetched, but could oil get past the valve stem oil seals. Then down the valve and back all the way into the carb bowl. Then leaking out of the carb bowl seal?

The rest of the carb is clean, it’s just the bowl that has oil on it.
I don't think that could happen but if you pull the plug out of cylinder #1 the combustion chamber would have to be full of oil to confirm your theory.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline SteveW

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Re: Very odd oil leak
« Reply #10 on: April 18, 2020, 05:27:03 PM »
I’ll have a look tomorrow and take some pictures. It’s doing my head in  :(
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline JezzaPeach

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Re: Very odd oil leak
« Reply #11 on: April 19, 2020, 09:48:59 AM »
Have you put oil down the throttle cables?
1972 CB500/4 K1 Gold
Wanted: my 500/4 UGP96M
from 1975-78. Garnet Brown.

Offline JezzaPeach

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Re: Very odd oil leak
« Reply #12 on: April 19, 2020, 09:52:30 AM »
Also is there oil on the gear shift shaft? And presumably the chain cover is on?
My shifter shaft seal was leaking and was finding its way to the chain and all over the sump
1972 CB500/4 K1 Gold
Wanted: my 500/4 UGP96M
from 1975-78. Garnet Brown.

Offline SteveW

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Re: Very odd oil leak
« Reply #13 on: April 19, 2020, 11:03:13 AM »
Throttle cables have not been oiled and gear shaft seal is new.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline JezzaPeach

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Re: Very odd oil leak
« Reply #14 on: April 21, 2020, 10:43:49 AM »
#1 float bowl is right behind where the head gasket o ring used to leak a little on my 500/4 back in the day. Could this plus maybe a restriction up the oil way cause a small amount to spray out and drift back on the air flow to the float bowl.
1972 CB500/4 K1 Gold
Wanted: my 500/4 UGP96M
from 1975-78. Garnet Brown.

 

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