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Discussion Starter · #1 ·
ok - i have trolled forums and all over the internet and i'm hoping someone can help me. i have a 1997 vulcan classic and i keep getting gas in my oil. almost all of what i have seen traces the problem back to the carburetor but it seems to be functioning correctly. i am by no means a mechanic but i can tear down and fix most things given time and instruction. here are some pieces of information:

the bike fouls spark plugs pretty quickly although the bike still runs ok (strange, i know). they seem to be carbon fouled (black). could my spark plugs not be firing hot enough?
i had the carb cleaned and the tank cleaned.
hypercharger with air filter seems to be clean and functioning correctly.
the petcock seems to work as it should though i leave it on all the time.
i recently saw that the nut on the choke cable entering the carburetor is broken and i am wondering if that is the issue.
the bike runs well most of the time with some backfiring here and there although it is pretty hard to start in the cold.
there is no smoke of any color ever.

anyone have any ideas? i am at a loss...
 

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Novice Tank Roller
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15,810 Posts
does the petcock have a vacuum on it, or does it have an "off" setting? You're likely getting fuel overlfowing the carb float, going into the cylinder, and seeping down into the oil around the rings. Definitely don't try to start or run the bike until you've changed the oil and check the cylinders. Sometimes the cylinders are full of fuel, and when the piston tries to compress it, you bend things inside.

Start by disconnecting the fuel line from the petcock and see if fuel keeps seeping out. Next have the carb checked. If you are fouling plugs, it's either because of the fuel leaking in, or your carb is running rich.
 

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Discussion Starter · #3 ·
thanks so much for the reply.
the petcock has three settings: on, off, reserve
unfortunately the bike been run quite a bit the way it is so...yikes!
how do i check the cylinders? if they are full of gas, will clearing them out take care of the issue?
when i disconnect the fuel line, fuel is not seeping.
i just had the carb rebuilt - should i take the bike back in? should the shop adjust the carb when it rebuilds or is that expecting too much?
 

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Novice Tank Roller
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if you've been running it, gas in the cylinder isn't a problem. it's only on startup that something would go wrong. Most likely, the rings allow it to drain enough to keep from harm.

Make sure to change the oil if it has fuel in it again. Also make sure you use the off setting when not running the bike.

go ahead and run it some since you just had the carb work done. You can check your plugs for soot after a few thousand miles and see how it's doing.
 

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If you are carbon fouling plugs and the petcock is not leaking, the carb needle and seat are not leaking, the float height is adjsuted to specifications and it is not a "sinker", the carb is adjusted as it should be, then there is the possibility that the fuel pump has too much pressure.
You will need a shop manual to check for correct pressure.
As NCDave said, it is best to shut off the tap when the bike is not running.
It may be dripping (the carb, that is) when you are not looking and can flood the cylinders over time...hence the hard cold start!
 

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some gas in your oil is normal more so if you just do short quick rides. The longer and higher rev you ride the less gas in your oil. When your engine gets hot from a longer ride it will burn the gas in the oil. When you first start the bike the seals are not perfect and some gas escapes during combustion and gets into your oil.
 

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I know nothing about that bike (and only a little about my own) but the broken nut on the choke cable/loose cable... could that be a seperate issue that is causing the hard cold start? Maybe look to see if the choke is doing anything to the (both/only?) carb.

Brian
 

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Mine is a '96 1500 and very similar if not the same. I would investigate the choke issue. In actuality, it is not a choke, but a fuel enricher. If the nut, you speak of, is broken, you might be getting a rich mixture when the bike is running. I would check that out first, before I went to something else.

The cold start problem............when you pull the choke out, I assume that the bike eventually starts, correct? If so, does it run at fast idle?

You might also check the bowl vent tube. It runs to a carbon cannister on some models and can give you fits. Try disconnecting it and running a hose, temporarily, to just down below the frame. See if the problem persists. A faulty cannister can sometimes increase the pressure in the bowl and cause the carb to run rich.

I am also wondering why the shop, that did the carb work, did not fix or at least inform you about the broken fuel enricher?
 

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V 2win
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The needle valve & seat isn't sealing & needs replaced, also the vacuum petcock isn't working properly. You need to put a new needle valve & seat in the carb, & at least remember to shut the petcock off every time you shut the motor off. Continued gas leaking in the oil will wash the bearings & you will have the rod & main bearings knock knock knocking on the junkyard door!
 

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The needle valve & seat isn't sealing & needs replaced, also the vacuum petcock isn't working properly. You need to put a new needle valve & seat in the carb, & at least remember to shut the petcock off every time you shut the motor off. Continued gas leaking in the oil will wash the bearings & you will have the rod & main bearings knock knock knocking on the junkyard door!

I agree .............needle and seat could be bad. Mine does not have a vacuum petcock.......I doubt if his does.
 
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