Question about 2001 BMW R 1100 RT (ABS)

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Fuel petcock How bad is it to leave the fuel petcock open for an extended period of time? I forgoten about it from time to time and it hasnt seemed to make much of a difference. I read somewhere it can affect the carbs, how likely is this happen and what might some symptoms be?

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If you have a stuck float valve, you could end up with your bike sitting in a puddle of fuel.
For safety's sake, you can turn it off.

Posted on Jun 29, 2009

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Depends on the bike and the fuel flow setup, but leaving it open can allow fuel to drain through the carbs, into the cylinders, and settle inside the crankcase, fouling the oil. Check your oil level and see if it smells like fuel.

Posted on Nov 20, 2008


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I have a 1988 gsx1100F and it seems to have fuel finding its way into the oil any ideas on why this would be happening? its also bogging out if i open the throttle up fast

Do you let it set for extended periods with the petcock on? I don't recall if that motorcycle has a vacuum diaphram that shuts fuel off when the engine is not running. Even if it does you may want to check that out and make sure its functioning properly.

Fuel may be going into that carbs and seeping past the needle seat in the float bowl. From there if comes out the carb and runs into a cylinder, through the piston rings and into the oil.

Also the bogging could be some flooding. May want to make sure your floats are working properly.

Sep 10, 2011 | 1988 Suzuki GSX 1100 F (Katana)

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1981 yamaha 650 what position should the petcok b in? pri res oo on

Fuel petcock position depends entirely on what you're doing with your bike at the time.

In normal use, the fuel petcock should be set to the "on" position and left there. In that position, gasoline will be drawn from the tank only when the engine is running and generating vacuum. This prevents overfilling the carbs when the bike sits.

When you're riding the bike and it starts to sputter, it's time to move the petcock to the "reserve" position so that you can use the last few drops in the tank (on a 650 special, this was either .3 or .5 gallons--can't remember which off the top of my head) to nurse your bike to a gas station. Once you've filled the tank, move the petcock back to "on." The bike will still run fine if you keep the petcock in the reserve position, but when it starts to run low on gas--well, you won't have that emergency reserve to get yourself to the gas station.

If you've managed to run the bike out of gas completely, or if you are getting the bike ready for service after having drained the carbs for the winter, you'll need to move the petcock to the "prime" position for a few minutes. This by-passes the vacuum line cutoff mechanism and lets gasoline flow until the carb floats shut off the fuel valve (this is also how all older motorcycle fuel petcocks operated). A sticky float or poorly sealing float valve in the carb can, however, cause far too much gasoline to drain into the carbs (and into the crankcase, if you're particularly unlucky), which is why you should not leave the petcock in the prime position for an extended period of time.

Some Yamaha XS650 motorcycles (can't tell if that's the model you have) have a tank with two fuel petcocks, one on each side, to fuel each carb. If you have a tank with this setup, be aware that setting one fuel petcock to "prime" will affect both cylinders, as there's a crossover tube to equalize fuel levels between the carbs. Also, for reasons I could never figure out, on one XS650 I owned, moving either petcock to "prime" permitted fuel to flow on a gravity feed out of both petcocks simultaneously. I could never figure out exactly why it was doing that.

Jun 06, 2011 | Yamaha XS 650 G Motorcycles

1 Answer

What would cause oil to get in the air filter? Also, what would cause the front tire to wear unevenly.

Uneven tire wear is caused by running with the tire pressure too low. Often 35 PSI will keep the tire wear more even. If you ride a long distance with a strong cross wind you may notice wear on the windward side of the tire (just off center). This is because after riding in the crosswind for a long period of time you have been leaning into the wind and are wearing the tire off center.
Oil on the air filter typically is coming from the crankcase breather. Check your oil, it is probably contaminated with gas from your tank and the oil needs to be changed as well as your air filter.
If you have a vacuum style fuel petcock , the vacuum diaphragm has a hole in it. The gas leaks past the diaphragm, down the vacuum line, into the intake manifold, into the cylinder, past the piston rings, and into the crankcase where it mixes with your oil.
If you have a standard on / off style petcock, all you have to do is leave your fuel on and have a float needle stick in one of you carburetors. The result is the same , the crankcase fills with all your expensive gas from the fuel tank. This can happen to any motorcycle that is in perfect order.
If the four hole washer in any style petcock gets worn (thin or torn) , that can be the cause of a fuel spill into the engine. Always turn your fuel petcock off when not riding.
Start with a thorough inspection of your fuel petcock for bad rubber parts. Replace any bad parts with new. K&L makes after market fuel petcock repair kits if you just want to rebuild . If money is no object a brand spanking new fuelcock will work for sure. If running a quality fuel system cleaner like "Chevron Techron" does not stop the carburetor float needles from sticking, your may have to disassemble the carburetors and clean them properly and replacing the float needles during the process.

Apr 17, 2011 | Suzuki GSX 600 F (Katana Motorcycles

2 Answers

About after a min of the bike running gas starts flowing into the air box, its alos getting into th oil

First check to see if the oil level in your crankcase is too high. If you have a vacuum petcock malfunction (hole in the diaphragm) or if the fuel petcock is left in the prime position and a float needle sticks, then you get you get gas running into the cylinders, past the rings, and into the oil.
When you start your motorcycle the oil/gas mixture has no place to go, the crankcase is too full, and the mixture exits through the crankcase breather into the air box where it will ruin a paper air filter. Always turn your fuel petcocks off when not driving. If the petcock diaphragms are bad rebuild the petcock with K&L rebuild kits or replace the fuel petcocks with new ones. If the float needles in the carburetors are bad or sticking, take the carburetors apart, clean them, and replace any worn or damaged parts You will have to change your gasoline saturated oil for it will no longer properly lubricate your motor.
Just a note: in 1983 brand new Honda's would fill there engines in gas. All the components were clean and new. This can happen to any machine in any condition at any time. When not riding always turn off the fuel vales never leave them in the prime position.

Mar 21, 2011 | 1982 Yamaha XS 400

1 Answer

Gas is leaking from the peacock valve under my gas tank seems to be coming directly from the bottom,what could cause this?

There's a gland nut that holds the petcock into the tank and pulls it up against the seal. Try tightening the nut. But, in all probability, it's the vacuum diaphragm in the backside of the petcock.

Harley went to a vacuum operated petcock in 1996 and they've been a pain ever since. The diaphragm gets a small hole in it and leaks gasoline or quits opening leaving the rider stranded.

Now, You can repair the petcock if you wish. Get a large funnel and an empty gasoline can. Loosen the petcock and allow the fuel to run out around the nut, catching it in the funnel and directing it into the gas can. Once empty, take the fuel line and the vacuum line off the petcock. The vacuum line is the small line on the backside. Take the petcock out of the tank. Look on the backside and there are four small screws. Take them out and carefully take the back plate off the valve. You'll see a diaphragm, a spring, and needle. Take the diaphragm and hold it up to the light and gently stretch it. You'll probably find a hole. You can get a replacement diaphragm from you local dealer. Reassembly is the reverse of disassembly.

Personally, I'd rather replace the vacuum operated petcock with a high quality manually operated petcock such as Pingel. The OEM petcock will fail on you and leave you stranded with a full fuel tank and an empty carburetor. The Pingle won't. Just install it, connect the fuel hose, and plug the vacuum hose.

Good Luck

Sep 12, 2010 | 2000 Harley Davidson FXDL Dyna Low Rider

1 Answer

My bike hasnt been ridden for a few months, and you need to give it full choke to start and keep it going, it wont idle when the choke is depressed, It is A Vstar 650 Classic

was fuel left in the carburetors when you parked it your metering jets might be slightly clogged with varnish i dont recomend opening them yourself take it to a professional and next time you park it for an extended period of time close the fuel valve and leave the bike running until the carbs run out of gas "the bike will stop running when this happens"

Jun 29, 2010 | 2006 Yamaha XVS 650 Dragstar Classic

2 Answers

Im trying to get my friends 82 yamaha 1100 to work. there is a severe fuel leak coming from what looks like all 4 carbs., into the inttake. i have looked over them with my minimal carb experience, and see...

The most likely cause is dirt or other contaminants causing the float valves to hang open and the carbs to overflow. This would be especially true if the bike has been sitting for more than just a couple of months.

You can first try draining the fuel from each float bowl and see if that stops the overflowing. Turn the fuel petcock off and then loosen the drain screw on the bottom of each float bowl. Turn the petcock back on and see if the problem persists.

If so, you're going to have to remove each float bowl and carefully remove and clean each float valve. Also clean the bowls while they're off. Cleanliness is critical - so clean everything before reassembly.

If the bike has been sitting for an extended period of time, this would also be a good time to clean all of the fuel varnish and other crud that is very likely clogging the carburetor jets.

May 23, 2010 | 2001 Yamaha V Star 1100 Classic

1 Answer

Engine turns over but won't start lots of back firing

It sounds like it's not getting fuel for one reason or the other. If the tread is correct, you '01 Sporty is equipped with the vacuum operated petcock. If the diaphragm is bad in the petcock, no fuel gets to the carb. If the vacuum line is off the rear of the petcock, the VOES switch, or the carb, it will get no fuel. These petcocks are known to be a problem area. I always advise the purchase of a Pingle petcock and replace the original. If the Pingle is too pricey, go for a stoke pre-1996 original equipment petcock.

Now, if the bike has been sitting up for a long period of time (longer than a year), you may have to remove, disassemble the carb, and clean the jets and air passages out. Regrettfully, this is not a job for most amateurs unless they are mechanically inclined.

Apr 22, 2010 | 2001 Harley Davidson XL Sportster 883...

1 Answer

I have a 95 dyna wide glide it has set for about a year when i started it fuel was coming out of the vent on the petcock

Did you leave your petcock on for a extended period of time? If so, this can cause flooding of the cylinders, which may or may not explain the problem. tough to say on that one, especially if its a fuel injected.

Apr 17, 2010 | Harley Davidson FXDWG Dyna Wide Glide...

1 Answer

Fuel getting into oil

Your carb are over flowing .a bad float needle could cause this .If it is fuel injection one of them is hanging open .That is the onle thing that would cause this

Feb 21, 2009 | 1999 kawasaki ZX-6R Ninja

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