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Gas in the tranny oil 2010 CRF250r Honda

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Here's the problem.. Last 2 oil changes I have notice gas in the oil on the transmission side..Clutch side is fine.. The only way gas could get in the oil is by seeping past the rings.. I just looked into the throtle body and it appears to be dry while the bike is just sitting not running... So I have installed prior to noticing this problem a Weisco Fuel Managment Control... Could it be running so rich extra gas is being injected and not burned therefore seeping past the rings?? I also did a top end a few months back. I offset the rings as shown in the manuel and the bike runs strong but I am at a loss for why and how the gas is getting into the oil. Eddie or anyone got any thoughts??? Thanks in advance..

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The injector is visible with the rubber boot off... There is no fuel leaking from the injector while the bike is sitting not running.. Thats what I thought may be happening but I have had the throtle body open all day and no gas has dripped from the injector... I'm thinking gas is getting past the rings during operation,, but u would think the plug would foul if that was the problem..and that much gas was getting into the oil.. Tomorrow I'm firing it up with the air boot off and will be able to see the gas squirt from the injector and what happens after I shut it down when the engine is hot..

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although i dont have experience with 4 stroke motorcycles, i have seen intermittently stuck open fuel injectors on multiple cars at work.

i would think that if your rings were worn enough to allow that much fuel to get past the rings you would have an oil consumption issue as well.

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I believe this was an issue Honda was looking into? They were pretty vague about it, and I'm not sure a real solution was offered. It might be on TT somewhere.

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The guy ar PC says that the fuel pump assembly starts going bad then leaks.. From there its all down hill and that why people think its the injector leaking.. I'm going to tear it down and find out..

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where is the fuel pump located on these bikes? in tank or are they external? I'm having a hard time visualizing how a fuel pump is going to cause this issue but then again I haven't seen how these FI bikes are set up.

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The fuel pump is in the tank. It can leak all day long and it won't fill up the cylinder unless the injector is leaking when shut off. If the injector were supplying too much fuel with it running, it would simply run too rich.

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where is the fuel pump located on these bikes? in tank or are they external? I'm having a hard time visualizing how a fuel pump is going to cause this issue but then again I haven't seen how these FI bikes are set up.

The fuel pump is not like the water pump. It's a 'pressure' pump like a pressure washer. When it starts to fail, gas get's by one of the pistons, and leaks out the injector.

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The fuel pump is in the tank. It can leak all day long and it won't fill up the cylinder unless the injector is leaking when shut off. If the injector were supplying too much fuel with it running, it would simply run too rich.

hmm, this is exactly the type of system i work on day in and day out (a few of "our" older cars have external fuel pumps, but all are in-tank now). i agree with your post and see no way a bad fuel pump is going to cause a leak of gas into the cylinder. the only connection between the fuel and the cylinder is the fuel line and injector. i just dont see how its possible other than to have an injector that intermittently sticks open when shut off, or just has a small constant leak.

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