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Discussion Starter · #1 ·
Can anyone tell me why my engine oil is full of fuel? I’ve recently bought the bike that has been standing for a few years and have had lots of problems getting it to run on all 4 cylinders. It’s been serviced, and carbs stripped and cleaned and still running like a bag of shit.
 

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if its a Fi model the Fuel Pressure Regulator will be the most likely cause, common(ish) issue, easy to test, and to replace. If its on carbs then you've other issues!!
 

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Discussion Starter · #4 ·
if its a Fi model the Fuel Pressure Regulator will be the most likely cause, common(ish) issue, easy to test, and to replace. If its on carbs then you've other issues!!
Hi yes it’s carbs, all floats seem to be sealing properly, all diaphragms are good, fuel tank diaphragm is good and the engine just seems to be getting way too much fuel and runs badly and like I said lots of fuel in the brand new oil change which I have had to bin. I’m struggling. Carbs stripped again and I can’t see anything obvious.
 

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Most of the time fuel in the oil is from the bowls overflowing and fuel runs into the crankcase past the rings. That is typically caused by the float needle not sealing or a bad needle seat in one or any of the carbs.

You mention “fuel tank diaphragm”, so I’m guessing it’s an SC33 97-99 900RR? Those do go bad and are easy to test.

Turn fuel to on with engine off and pull the big hose of the valve. Fuel should NOT flow. It should only flow with engine running, as it has a vacuum valve to stop flow and alleviate the very problem you’re describing.
 

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Discussion Starter · #6 ·
Most of the time fuel in the oil is from the bowls overflowing and fuel runs into the crankcase past the rings. That is typically caused by the float needle not sealing or a bad needle seat in one or any of the carbs.

You mention “fuel tank diaphragm”, so I’m guessing it’s an SC33 97-99 900RR? Those do go bad and are easy to test.

Turn fuel to on with engine off and pull the big hose of the valve. Fuel should NOT flow. It should only flow with engine running, as it has a vacuum valve to stop flow and alleviate the very problem you’re describing.
Correct with the model and yes I have changed the fuel tap diaphragm and checked and it works. I have stripped carbs checked float needles by blowing through the fuel pipe and they seem to be ok but fill the float chambers with fuel and it does run through carbs so something not right( strange) stil doesn’t explain why the engine filled with fuel unless it was when it was running. What’s the remedy for bad float seats? Can they be replaced ?Regards.
 

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I know for the 98-99 the seats are removable, not sure on the 96-97. But here’s a tip I’ve used in the past for seats that may be slightly buggered up:

Take a Q-Tip brand cotton swab and chuck it in a cordless drill. Use a fine metal polish like Mothers Mag Polish and get some on the Q-Tip. Spin it up with very light pressure on the seat. If the seat is what was letting the fuel in, that should help better seat the needle. Also, you can replace the needles, as the rubber end does fail if left unused for a long period of time.
 

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Discussion Starter · #8 ·
I know for the 98-99 the seats are removable, not sure on the 96-97. But here’s a tip I’ve used in the past for seats that may be slightly buggered up:

Take a Q-Tip brand cotton swab and chuck it in a cordless drill. Use a fine metal polish like Mothers Mag Polish and get some on the Q-Tip. Spin it up with very light pressure on the seat. If the seat is what was letting the fuel in, that should help better seat the needle. Also, you can replace the needles, as the rubber end does fail if left unused for a long period of time.
Thank you for the advice I will have a go.
 
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