Motorcycle Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
39 Posts
Discussion Starter #1
Ok here is the problem. I have an 08gs500f, 8000 miles, carbs just cleaned 1500 miles ago. I filled the fuel tank up maximum, got stuck in gridlock traffic on the interstate. Bike just died and wouldnt start again. Started leaking fuel out of a black capped rubber tube next to rear foot brake.

I have it parked in autozone parking lot right now, I think this all has happened due to me running the bike for past 1000 miles with petcock set to "PRI". I left the bike with the petcock set to "Off", because autozone guys said the carbs may be flooded.

This is my first bike, I suspect the problem is because something is flooded from the petcock being in the prime position. Or maybe an O-ring has broken in the carbs, preventing proper operation. Any thoughts or advice?

If I can get the bike to start should I ride it home (about 5 miles). I can also walk it or have it towed. Also, is the solution going to require a mechanic? I am a mechanical engineer and am wanting to get into track days so it may be worth me doing it on my own.
 

·
Premium Member
Joined
·
5,640 Posts
The PRI position bypasses the vacuum-operated part of the petcock, so that fuel will flow when the engine is not running. If everything is working, that should not be a problem, but, if the float levels were set wrong when they were cleaned, or a float valve sticks, the carbs will keep filling, until they overflow. If it only flows out that drain, then no harm was done, but, it could also flow into the engine and into the oil, so smell the oil for gasoline, and check the oil level, before trying to start it. I'd get it home to check the float levels and un-stick the valves, if needed, then check the oil.
 

·
Registered
Joined
·
39 Posts
Discussion Starter #3 (Edited)
Thanks for the reply WintrSol, I realized my bike had been running in the PRI position for over 1000 miles, and the bike was also a bit hard to start today, and died at idle once. The weather was about 80 degrees. This is the first time the bike has done this, so I am taking it I need to disassemble some things. Bike is only leaking fuel out that drain, I actually had a track day moto guy in the parking lot come look at my bike to confirm that there are no other leaks.

From your post. this is what I need to do:

-Get my bike home without it running, even if it can run somehow miracuously. If my oil smells ok can I run it, or try to?
-Turn petcock to OFF position to prevent the issue from occurring again, and possibly this will help start the engine again if the case is this simple.
-Check oil, will most likely replace it either way.


Not really sure what to do, if anything, about the float valve sticks, I'll have to read up on it, I'm hoping it doesn't require too much dissassembly.

This is the first time I have noticed this leak though, however.

Sorry if my post is a little scrambled, my brain is fried, my body is dead from pushing the bike a few miles, and I am a noob.

I just don't want to compleltely screw up my bike by running it with thin oil or something. Thanks in advance
 

·
Ace Tuner
Joined
·
2,914 Posts
One other thing, check the fuel tank for rust or other debris.
Trash of some sort could have caused a float valve to hang open.
When running the petcock in the Pri position, fuel is drawn from the bottom of the tank where trash usually settles.
 

·
Registered
Joined
·
39 Posts
Discussion Starter #5 (Edited)
Okay so I went to check on it this morning, turns out I was riding the bike with petcock set to RESERVE.

The other two options are PRIME and ON.

The bike wouldnst start up this morning and was leaking lots of gas still overnight. probably half my tank is gone.

Looks like I need to look at these valves. Are there special tools needed for this or am I going to be able to do it myself with wrenches, sockets, allen heads, etc?

Ideas on cost if I take it to a shop?
 

·
Registered
Joined
·
39 Posts
Discussion Starter #6
The dealer just quoted me 20 bucks to pick it up. and 300 to work on it and fix it.

I have no garage to work on this sucker so unless you guys think this is aneasy fix I'm just going to go ahead and do this.
 

·
Gone
Joined
·
23,907 Posts
It sounds like there are two things wrong with the motorcycle.

The fuel valve set to on or reserve should not allow fuel to get past the valve. If fuel is leaking through in these two positions, it is defective.

The float valve in the carb is designed to stop the fuel flow once the carb bowl is full. If fuel is leaking past these, they are also defective.

The fix is a rebuild of the petcock and at least a partial disassembly of the carbs. If the floats in the carb are damaged, they need to be replaced. It could also be the float needle or seat that is causing the problem, or even the adjustment.

$300 is probably the correct range of what it would take to have these things done, depending on how much work it would take to get the carbs and valve off.
 

·
Registered
Joined
·
39 Posts
Discussion Starter #8
defective as in the parts need replaced? or as in they need realligned/readjusted. Thanks for your guys help. Is this gonna be over my head as a beginner? I would for sure do it myself but the bike is stranded so I'd have to pay for towing to get it 5 miles down the road to my place.
 

·
Premium Member
Joined
·
5,640 Posts
As noted by others, there could be flakes of rust and/or other junk in the bottom of the tank that caused all these problems. With the petcock in reserve, it draws from near, or at, the bottom of the tank, but the vacuum valve should still shut it off. Junk from the tank could block the valve from closing, though. Same for the float valves in the carbs. I suggest you drain the tank, remove the petcock, and give it a flushing out. Then, you have to take the petcock apart to clean it out, so might as well install a rebuild kit there. Neither needs a garage, just a ventilated space, and someplace to dispose of the old gas. Once this is done, you can test the petcock with the fuel line disconnected from the carbs; I'd use some kerosene, as it is a lot safer, just be sure to drain it before putting gasoline back in. Petcock in ON or RES, no fuel flow, unless you pull a vacuum on the hose from the carbs; PRI, and fuel flows all the time. If it won't pass the test, you put it together wrong, so try again.

The float valves could be simple, if you can easily remove the bottom of the carbs (float bowls) while they are still on the bike. Once the tank is back on with a clean petcock, put some gas (or even kerosene, which is safer) in the tank, and test the float valves. One at at time, remove a float bowl, prepare to catch the fuel, and set the petcock to PRI. Fuel should begin flowing, until you lift the float until it gently presses the valve closed, when it should stop. If it still leaks, even a little, the valve needs replacing, as the seating surface is too worn. If the valve is working, put the bowl back on, and connect a length of clear tubing to the bowl drain, turned up in a U shape alongside the carb. Open the drain and petcock, and the fuel will rise in the tube to the set level. If that level is really close to where the bowl seals against the carb body, it needs resetting. I don't have the numbers, but it is usually about 1/4" to 1/2" below the body. If you can't easily get the bowls off, it gets harder, as you have to remove the carbs and bench test the floats; you may need an experienced carb guy to show you how, but there are videos on YouTube on this.
 

·
Gone
Joined
·
23,907 Posts
It's not terrible difficult to do, but it's all relative to someone's mechanical ability.

The one thing you don't want to do is strip any bolts or screws, as that could end up costing a lot more.
 

·
Ace Tuner
Joined
·
2,914 Posts
Clean/go thru carbs, $300 = $150 per carb, little more than what I charge but probably fair enough.
They'll also need to fix the petcock.

Good Luck, Take Care
 

·
Registered
Joined
·
39 Posts
Discussion Starter #12
Thanks guys. Yeah the total max bill will be 310-350. That includes parts and them picking the bike up for me.

I'd do it myself but I don't have the time right now, nor the space (I live in an apartment).

I'll do it myself in the future though because it seems straight forward once you know how everything works.

Thanks!
 

·
Premium Member
Joined
·
8,911 Posts
Easy Beazy

Do, it is straight forward when you have a little experience. However things are never straight forward.
I just removed the fuel taps on my mint XS1100. Larry the previous owner had rounded the inside of the philips head screws. He had also used an incorrect O ring. Just getting the screws out might stop a new would be mechanic. So rule number one: If you are not sure, at least do not bugger up the part.
You will be needing one of those impact twisty whacking things. And much patience with a Sherlock Holmes attitude.

The other way to learn is having a bike and being broke.

Unkle Crusty*
 

·
Premium Member
Joined
·
5,640 Posts
Yes, the screws are all JIS, so a good-ole Phillips will strip them pretty fast, leaving a mess you need a hammer-driver or a backwards drill to remove. Neither is a good option on the parking lot of an apartment complex (been there!).
 

·
Ace Tuner
Joined
·
2,914 Posts
Sometimes you can get a small vice-grip on the head of the screw to brake them loose.
If it doesn't loosen right away with a screwdriver, I get the vice-grips out. An impact driver can be used also.
But you have to have the carb caps off to avoid damage while pounding.
You'll need to have the carbs on the bench to do it, not on the bike of course.
 
1 - 15 of 15 Posts
Top