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Discussion Starter · #1 ·
My bro's '77 Sporty has been running like a champ, but he called me over tonight in a panic. Earlier, the bike had been a bitch to start, then apparently shot about a quart of oil outta the vent tube off the right side of the generator housing and wouldn't rev, then the oil pressure light came on. He killed it and called me, and after checking the oil level we fired it back up - started right up, and at idle there was no more oil outta the vent tube, but the oil light stayed on steady so I killed it until we can replace the light with a real gauge.

Anybody got any thoughts? Oil pump? Figured the oil outta the vent tube might be a tell-tale symptom for somebody who knows these things.

Any help would be appreciated.
 

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There might be a possibility that he left the gas on and it siphoned into his cylinders causing a lock up, and since the engine oil level was high it shot the excess out the vent tube. Check to see if the oil smells like gas. Another scenario is that somthing got jammed in the oil pump leaving the diaphram open, letting oil from the tank into the engine resivoir(sp) the oil light is just a pressure switch that closes he circut when oil pressure is applied if it went on it was working. (most likely) But the real issue is you had too much fluid in the engine res. whether it be oil or gas. So just its that you have to figure out why. If you have gas in your oil you have to do a real good job flushing you engine otherwise the gas is going to break the oil down and bye bye motor.
Fastsporty
 

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I've seen scooters puke a lot of oil out of the vent tubes when they've been setting for a while, usually a couple of weeks or longer. Since the cases are lower than the oil tank the oil gravity feeds past the check ball and into the lower end. When you crank the engine the scavenger side of the oil pump can't pump all of the oil back into the tank quick enough and the oil takes the path of least resistance-out the breather. This is a one time deal until the bike sets again. This wouldn't have anything to do with the oil light staying on though. Check the pressure with a gauge. If there's oil in the tank and the gauge stays on zero, the first thing to check is the oil pump. If it picked up trash and locked up, it can strip the key in the drive gear on the pressure side of the pump.
You could also check the pump by pulling the return line off of the oil tank. Crank the engine an if everything's working it'll pump oil out of the line. No oil coming out of the line--check the pump.
Larry T
 

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Ok larry this is where I get confused... He said it was hard to start and then it ran rough and wouldn't rev, which is a sign that the plugs could be fouled. Which is why I first went with the gas in the oil. But then he has the oil light issue, what he sheared the pin and then it some how caught again? giving it oil pressure. then he said it puked out a 'quart of oil ' but then when checked it was fine. even if it wasn't a quart of oil you still would of noticed the oil being lower.
Who knows? like I said Blake check the oil to see if it smells like gas, when you put a gauge on it be prepared that the pressure is real low at idle like sometimes less than 3 lbs especialy if you use that little plug between the lifters, see that you are getting return oil in the tank, another little trick i learned is to use a clear piece of tubing to go back in your return than you can see the oil flow. Also listen to see if your oil pump is making any weird noise or slipping, not easy but try to check it out anyway.
let us know
fastsporty
 

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Blake, when my bike sat for two weeks, it puked almost all the oil out.
I re-filled it, and have had no problem since.
I was just away for a week, started it yesterday, and it fired right up with not a drop out the vent.
I was told that the check valve can get stuck, so maybe start there at the oil pump.
G.
 

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fastsporty said:
Ok larry this is where I get confused... He said it was hard to start and then it ran rough and wouldn't rev, which is a sign that the plugs could be fouled. Which is why I first went with the gas in the oil. But then he has the oil light issue, what he sheared the pin and then it some how caught again? giving it oil pressure. then he said it puked out a 'quart of oil ' but then when checked it was fine. even if it wasn't a quart of oil you still would of noticed the oil being lower.
Who knows? like I said Blake check the oil to see if it smells like gas, when you put a gauge on it be prepared that the pressure is real low at idle like sometimes less than 3 lbs especialy if you use that little plug between the lifters, see that you are getting return oil in the tank, another little trick i learned is to use a clear piece of tubing to go back in your return than you can see the oil flow. Also listen to see if your oil pump is making any weird noise or slipping, not easy but try to check it out anyway.
let us know
fastsporty
Fastsporty,
I was just throwing out some more stuff to check. It's kinda hard troubleshooting a problem over the internet (or telephone for that matter). Like, does the engine turn over ok and not start or does the engine turn slow or act like it's locking up (hydraulic)? You made a real good point about checking for gas in the oil. What I've seen on the oil pressure gauge deal, sometimes scooters have VERY low oil pressure at idle when they're warmed up, but usually come up off the peg when the engine is cold.
I don't really understand what you're talking about on the no oil pressure then having oil pressure again deal.
Back to the shop. I just got a customers flywheel assembly back from Truett and Osborn a couple of days ago and he wants his bike running for some reason.
Later,
Larry T
 

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Discussion Starter · #7 ·
Thanks for the insight, guys. The plugs were fine - checked them last night. He rides the thing at least weekly, and it's been fine. We did change the oil two weeks ago, but he's ridden 3-4 times since then with no problem. Sounds like the oil pressure light/vent tube dumping is somehow related. I'll check to see if the oil smells like gas, and will check to see if he's getting oil back into the tank. The biggest worry right now is the oil light staying on - need to get a gauge on it pronto, then diagnose the oil flow. Real worried about running it without pressure.

I'll let you know what we figure out.
 
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