Fuel leak after riding

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cidair
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Fuel leak after riding

#1 Post by cidair » Wed Jul 27, 2016 4:54 pm

I have a problem with my bike leaking fuel. It is always after riding ( engine has been running ). It smells fuel ( leaks? ) a couple of days in the garage, and then stops.
It doesn't seem to be the fuel cock. Could it be the carbs?
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
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samsarangi80
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Re: Fuel leak after riding

#2 Post by samsarangi80 » Wed Jul 27, 2016 8:33 pm

Hi Daniel
yes it could be the carbs.Since it is leaking when the bike is running and not when it is standing still tells me that some hose connection to the carbs is leaking .It must be the one that is after the T connection at each carbs .
You can put the fuel lever to prime and check when the bike is at standstill and observe if it leaks.
All the best.
My rides
Aprilia RS250 - 1998
Race ready RD500
Bone stock RD500

cidair
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Re: Fuel leak after riding

#3 Post by cidair » Thu Jul 28, 2016 7:15 am

Sorry if I was unclear, but it is leaking fuel when it is standing still. It stops after a copke of days in the garage. Then if I run it again and put it in the garage it starts leaking for some days.
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
R1M -15
750 H2 -72

2002tiil
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Re: Fuel leak after riding

#4 Post by 2002tiil » Thu Jul 28, 2016 9:05 am

I had the same thing: It was/were the float valve/ seat.
It could be some particles what makes the float valve not shut down fuel delivery.
The float seat could be a problem due to be not that smooth as it should be: Take them out, put a cue tip on an electric drill with some abbrassive polish and clean up the seats.
You could allso buy a new set, like from Keyster

Sorry for my bad english,

Richard

silverstrom
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Re: Fuel leak after riding

#5 Post by silverstrom » Thu Jul 28, 2016 11:22 am

cidair wrote:Sorry if I was unclear, but it is leaking fuel when it is standing still. It stops after a copke of days in the garage. Then if I run it again and put it in the garage it starts leaking for some days.
2 problems. First, your petcock is leaking and letting fuel past when it shouldn't. Second, your float valves need replacing. The needle tips get hard due to ethanol and age and no longer seal properly against the seat. Solving both problems is the correct answer. Solving only one should still stop the leaking.

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phildu31
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Re: Fuel leak after riding

#6 Post by phildu31 » Thu Jul 28, 2016 12:09 pm

Hi,
Since your leak stops after a couple days, it's probably that your petcock is (still) ok.
Try to put it in prime and look if the leak appears, if yes, your petcock is (still...) ok.
Next try to identify where the leak comes from: is it from one carb overflow hose ? or several ? or else ?
Once you have identified your leaking carb, check also the fuel level with a clear hose in the drain nozzle.
A level a little bit too high would result in a little spill over.

cidair
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Re: Fuel leak after riding

#7 Post by cidair » Thu Jul 28, 2016 12:22 pm

Thanks everyone!
I guess there will be some nice garage time, with my 500. :-)
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
R1M -15
750 H2 -72

silverstrom
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Re: Fuel leak after riding

#8 Post by silverstrom » Thu Jul 28, 2016 3:13 pm

Thinking about it again, and the fact that it stops after a few days not running, I think there is a good possibility that the leak is from the bowl. A slow drip over a few days until the bowl is dry then the leak stops. In that case you want to check the bowl drain screws to make sure they are tight. Also check the bowls for very small cracks.

You ride the bike which fills the bowls. You park the bike and it drips until the bowls are empty, typically a couple of days, and the leak stops. You ride the bike again which fills the bowls and the cycle repeats itself.

cidair
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Re: Fuel leak after riding

#9 Post by cidair » Thu Jul 28, 2016 5:36 pm

silverstrom wrote:Thinking about it again, and the fact that it stops after a few days not running, I think there is a good possibility that the leak is from the bowl. A slow drip over a few days until the bowl is dry then the leak stops. In that case you want to check the bowl drain screws to make sure they are tight. Also check the bowls for very small cracks.

You ride the bike which fills the bowls. You park the bike and it drips until the bowls are empty, typically a couple of days, and the leak stops. You ride the bike again which fills the bowls and the cycle repeats itself.
This was one of my thoughts too. I'll dig into it. :-)
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
R1M -15
750 H2 -72

rd84
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Re: Fuel leak after riding

#10 Post by rd84 » Fri Jul 29, 2016 6:34 am

If the float valves are letting fuel past you will see fuel in the overflow lines from the carbs - as said above it can also be a combination of faulty float valve (and/or float height setting) and fuel tap.

Cheers
Paul

cidair
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Re: Fuel leak after riding

#11 Post by cidair » Tue Aug 02, 2016 1:59 pm

Started looking into it today.
Found a cracked fuel hose, on the left rear carb. It's the fuel supply hose, coming from the forward carb. So I guess this was it? Seems too easy?
I saw the leak immediately after starting the engine with the cowls off. It was constantly dripping during engine running. Still drips after engine shutdown. But much much less.
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
R1M -15
750 H2 -72

cidair
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Re: Fuel leak after riding

#12 Post by cidair » Tue Aug 02, 2016 1:59 pm

Nothing coming from the vent lines on the bowls.
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
R1M -15
750 H2 -72

cidair
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Re: Fuel leak after riding

#13 Post by cidair » Tue Aug 02, 2016 2:41 pm

What is the right diameter ( inner/outer ) for the fuel supply hoses?
RD 500 1GE -87
RD 350A -73
TZR125RR 4DL -91
MT-09 -18
R1M -15
750 H2 -72

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tacky1
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Re: Fuel leak after riding

#14 Post by tacky1 » Tue Aug 02, 2016 4:54 pm

This is the fuel line I use for all my bikes, Fits the 500 perfectly,,

http://www.ebay.com/itm/Motorcycle-ATV- ... -U&vxp=mtr" onclick="window.open(this.href);return false;
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

silverstrom
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Re: Fuel leak after riding

#15 Post by silverstrom » Tue Aug 02, 2016 6:55 pm

As long as it's not smaller at the i.d. than the outlet and inlet pipes you'll be fine.

Give this a quick look. It's helpful http://www.rzrd500.com/500phpBB3/viewto ... 432#p71432" onclick="window.open(this.href);return false;

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