1999 800 (DANGEROUS) gas leak solved, sort of
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1999 800 (DANGEROUS) gas leak solved, sort of
A coupla days ago I made a post describing an unusual fuel leak... maybe you read it. I am make a new post here in an attempt to get as many members to notice it, and read since I consider what happened to be potentially dangerous.
In that first post I described the leak... a leak showing just aft of the oil level sight gauge... gas mixed with oil... no other sign of leakage.
It was a head scratcher at first, but I slept on it, then the next morning, as I thought about the possibilities... Bingo! I think I mostly figured out what had happened.
(I have been riding 800's since my first one purchased new in 1994, rode it until 2004 when I sold it a bought a low miles 1999 (this one).) Its been nearly been trouble free until now.
Since there was no other sign of any gas leak, the only thing that I found possibly suspect was the manual fuel valve. The 'normal' position should only supply fuel when the engine is running due to the vacuum switch. But once or twice in the past I have found the seals to fail and gas would leak past the valve with the engine off. Also, for some reason the carb. float valve would allow gas to enter the carb but not the crankcase (that I am aware of).
So today I pulled the hose on the outlet port of the manual fuel valve. Sure enough, I watched a slow drip, drip drip verifying it was leaking (with no vacuum).
I live in California so I rarely 'winterize' my bike. But I had not fired it up for several weeks prior this event. I am surmising that somehow, during that several week period, gas was leaking past the fuel valve, then past the float valve, then past an open intake valve, then past the piston rings in that cylinder, and into the crankcase. That drip, drip, drip, over time was enough to fill the crankcase TO THE TOP with gas and eventually find its way to what I am guessing is a crankcase breather port just above where I initially spotted the leak (just aft of the oil level sight gauge).
So today I drained the crankcase of all that gas (and oil), flushed with some clean oil, then replaced the oil and filter. (I had put 18 miles on it since fill up when I parked it. A visual inspection of the gas level showed the tank to be nearly empty of course.)
I fired it up after a much longer start sequence than normal, but after that it both starts and runs normally... with one other unexpected consequence. The clutch behaves entirely different from 'normal'. Its my best guess that bathed in gas, rather than oil all that time the oil was washed away from the friction plates causing the different behavior. Temporary? Permanent? I just don't know.
I keep my bike in the garage and generally give it an eyeball now and then as I walk by. That's how I noticed the pool of what I initially thought was an oil leak. But what in the world would have happened if say, I decided to go for a ride the previous day... just before it overflowed onto the garage floor... or a few weeks ago when say, the crankcase was half full of gas. I shudder to think.
It would be great to hear from a member who knows more about these engines than I do like "am I right that there is a crankcase breather port just about where I spotted the leak?".
Or does my theory sound crazy?
Or has anyone ever heard of this kind of situation. (I find it hard to believe I am the first to ever have had this problem).
In that first post I described the leak... a leak showing just aft of the oil level sight gauge... gas mixed with oil... no other sign of leakage.
It was a head scratcher at first, but I slept on it, then the next morning, as I thought about the possibilities... Bingo! I think I mostly figured out what had happened.
(I have been riding 800's since my first one purchased new in 1994, rode it until 2004 when I sold it a bought a low miles 1999 (this one).) Its been nearly been trouble free until now.
Since there was no other sign of any gas leak, the only thing that I found possibly suspect was the manual fuel valve. The 'normal' position should only supply fuel when the engine is running due to the vacuum switch. But once or twice in the past I have found the seals to fail and gas would leak past the valve with the engine off. Also, for some reason the carb. float valve would allow gas to enter the carb but not the crankcase (that I am aware of).
So today I pulled the hose on the outlet port of the manual fuel valve. Sure enough, I watched a slow drip, drip drip verifying it was leaking (with no vacuum).
I live in California so I rarely 'winterize' my bike. But I had not fired it up for several weeks prior this event. I am surmising that somehow, during that several week period, gas was leaking past the fuel valve, then past the float valve, then past an open intake valve, then past the piston rings in that cylinder, and into the crankcase. That drip, drip, drip, over time was enough to fill the crankcase TO THE TOP with gas and eventually find its way to what I am guessing is a crankcase breather port just above where I initially spotted the leak (just aft of the oil level sight gauge).
So today I drained the crankcase of all that gas (and oil), flushed with some clean oil, then replaced the oil and filter. (I had put 18 miles on it since fill up when I parked it. A visual inspection of the gas level showed the tank to be nearly empty of course.)
I fired it up after a much longer start sequence than normal, but after that it both starts and runs normally... with one other unexpected consequence. The clutch behaves entirely different from 'normal'. Its my best guess that bathed in gas, rather than oil all that time the oil was washed away from the friction plates causing the different behavior. Temporary? Permanent? I just don't know.
I keep my bike in the garage and generally give it an eyeball now and then as I walk by. That's how I noticed the pool of what I initially thought was an oil leak. But what in the world would have happened if say, I decided to go for a ride the previous day... just before it overflowed onto the garage floor... or a few weeks ago when say, the crankcase was half full of gas. I shudder to think.
It would be great to hear from a member who knows more about these engines than I do like "am I right that there is a crankcase breather port just about where I spotted the leak?".
Or does my theory sound crazy?
Or has anyone ever heard of this kind of situation. (I find it hard to believe I am the first to ever have had this problem).
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