Fuel in Oil... How to get rid of it???

[bjcrown]

I'm in Australia and own a 2004 GSX-750F and has only done 9,800km - 2nd owner with a K&N Filter. I've had the bike for 4 months and noticed a fuel smell coming from between the dash and the tank area after each ride.

I checked all fuel lines/connections, replaced spark plugs and fuel filter but to no avail. I also noticed fluid in the airbox which I drained and this too smelt of fuel.

I then changed the oil. Straight away the smell had dissapeared. A week later I opened up the bottle containing the old oil and noticed the fuel smell in the old oil coming from the bottle. So definately fuel in the oil.

Now after some 500km, the bike is starting to smell "fuely" again but not as strong (as yet!).

The bike runs well and very happy with it but this smell is getting to me. My older carby bike (Kawasaki ZZR-250) never smelt like this.

Can someone please advise what needs to be done to rectify this?

Looking forward to your advise.

Thanks.

[GregS]

The only "connection" for fuel to get into the oil is thru the carbs. I'd say check for high float levels or a leaking fuel tank valve. I don't know if Australia uses the same vacuum operated valve we have in the US, ours has no "off" position.
Also clean the airbox and its drain when you fix the cause of the leak.

[BarMatt80]

As greg said, check float levels. I am actually betting on that it is a stuck float, that allows fuel to keep flowing and flowing. You should only use prime on the tank if the bike has been sitting for a while or you run it out of gas. Ensuring that that you don't run the bike with it on prime and more importantly that you do not let the bike sit on prime this will help stop this problem. Reason for this is on prime the fuel just flows, so if you have a float stuck open, then fuel will flow and flow even after your bike is off. So make sure you use Reserver and primary tank so when the bike is off the fuel stops flowing.

Check your oil as normal, if it is higher than what you initially put in there, then you most likely have fuel in it. Also I think if you have raw gas in the air filter box, then you definately have it in your oil most likely. You need to drain the oil and refill.

[Black_peter]

The float valves should be able to hold back the fuel from the tank.. Should..

If your oil level is not rising I'm going to bet on bad fuel valve, the floats are just seeping gas by.

[ThAzKat]

it is a carb deal, fuel seeps through the valve train into the oil, just enough to give off a odor. clean carbs and adjust the floats

[md86]

And most likely one or more plugs would be dark , too .

[crazypj]

Its really common when bikes been sitting on prime. Can happen overnight. Fuel leaks past float seat into intake, through valves and down past rings. Over time you can get crankcase filled completely to top. If it happens on cyl 1 when valves are closed its possible to hydro lock engine when valve opens and dumps complete intake full of fuel into cylinder (that tends to break things)
Basically, don't run on prime, use it to prime carbs if you run out of fuel.
PJ

[bjcrown]

Since I've had the bike, I've only used fuel with a RON rating of 98. Would this do any harm? I would think not. Just curious.

Thanks for your replies. The fuel valve on my bike has the following postions: Res, On and Pri. I have never used the Prime Position. How does one check if this faulty? I do remember when I removed the tank there was no fuel coming from the fuel valve when set the On or the Reserve postions. As expected, fuel starting flowing when the valve was set to the Prime postion. What other checks can I do?

I guess, as per the responses given, it sounds like it's the carbs / floats. How do I check the floats and clean the carbs? Are there any instructions as I've never pulled apart carbies before but am willing to do so!

Thanks heaps.

[crazypj]

Getting carbs off is real easy, disconnecting cables is the hardest part. (actually, putting them back on is)
Every service manual shows carbs completely inverted to check float level but you actually need to tilt them to about 60~70 degrees so float tab just contacts shut off valve. Measure from gasket surface to high point on float. You will want to remove shut off valves to check for dirt, etc before checking. If you pull plugs it may show only 1 or 2 needed doing but its worth checking all of them while you have it apart.
PJ

[md86]

But you don't have to remove the cables to check float level .

[The CyberPoet]

To check for a faulty petcock:
set petcock to RES, engine off, and remove fuel line to the carbs. If any fuel flows through the petcock under this circumstance, it's defective in the way that may cause your issue (usually when they fail, they fail the other way, not letting sufficient fuel through when running).

The carb floats are like toilet bowl floats, sitting in the bottom and act as per-carb shut-off valves for additional fuel. If one of these gets stuck anything but the up position, excess fuel can run out of the carb and into the engine and airbox (whether it runs forward into the engine or backwards into the airbox depending on the angle of the bike at time of leakage** and whether it's running at the time).

There's a write-up on how to do the carb rebuilds here:

http://katriders.com/vb/showthread.php?t=63344

** NOTE: there is one other cause of fuel in the airbox and that's bad o-rings/bad compression. In such cases, fuel-air mix is pushed down into the engine in too large a quantity past the o-rings, mixes with the oil, re-evaporates when heated and then gets drawn back into the airbox via the vapor recovery tube between the top of the valve covers and the airbox. If the vapor is too fuel-rich, it can recondense at the airbox instead of getting reburned as it should.

PS - if there's fuel in the oil, it decimates the oil's viscosity and the oil needs to be changed as well -- once you fix the source of the fuel getting into the oil.

Cheers,
=-= The CyberPoet

[bjcrown]

CyperPoet,

Thanks for your reply.

With Regards to the checking of the petcock, does the engine need to be warm or can it be checked when cold (like the next day after a ride)?

Now when removing the fuel line to the carbs (the same hose that as the fuel filter) which end do I remove? I'd take it it's the petcock end? If that's the case, are you saying that the tank is still on the bike and whilst the the vacuum and breather hoses attached you only remove the fuel hose from the petcock? At this point, not one little drop should appear from the petcock?

Please advise.

Thanks heaps.

[The CyberPoet]

With Regards to the checking of the petcock, does the engine need to be warm or can it be checked when cold (like the next day after a ride)?

Operation should be identical irrelevant of the bike's temp. If the engine is off, the petcock should NOT flow any fuel when in RES or ON (but will flow freely in PRI).

Now when removing the fuel line to the carbs (the same hose that as the fuel filter) which end do I remove? I'd take it it's the petcock end? If that's the case, are you saying that the tank is still on the bike and whilst the the vacuum and breather hoses attached you only remove the fuel hose from the petcock? At this point, not one little drop should appear from the petcock?

Yes, remove the fuel line at the petcock -- which eliminates the need to remove anything except the fairing to get at that hose clamp (you don't need to move the hose far, just enough that the nipple exits to air so you can see if it's continuously flowing fuel or not).

A bit of fuel may appear when you first remove the hose (have a rag handy) -- drops that were between the internal shut-off valve and the hose nipple at the time the bike last shut down. But if you wipe those away, no further drops nor fluid should appear. If it's defective in the way we're talking about, it's apt to flow fairly heavily, but in working correctly it shouldn't even drip. Wipe away any excess, then keep your eye on it for the next 60 seconds. If it doesn't leak, then your problem is solely a carb float; if it does leak, then you have both a petcock and float issue (because it always involves a carb float if this problem occurs).

Cheers,
=-= The CyberPoet

[crazypj]

But you don't have to remove the cables to check float level .

I know, but its so much easier on the bench (particularly if you've never done it before)
PJ

[DreKat]

by chance is your peck cock set to Prim? I left mine on Prim all winter long a few years back and found the oil pan was full to the brim with gas.