Ok I know there have been a few posts on this but I never saw any resolution. I have a 2012 yz450f with approximately 35hrs on it. yesterday when changing the oil I noticed a strong gasoline smell and it seemed like I got a lot more oil out of the bike than normal therefore I suspect somehow some fuel got in the oil. I run Rotella triple T and regular 93 gasoline the motor is all stock and has never been apart. Any info would be appreciated to easy my mind about this. Thanks!
2012 yz450f gas in the oil
Posted November 17, 2014 - 01:31 PM
Otherwise, it could be a faulty injector either not firing at the right time, for too long of a duration, or otherwise allowing excess fuel into the cylinder that drains down past the rings into the crankcase. I don't know what the probability would be of an injector problem in these bikes, though I have heard of car injectors getting stuck open and causing this problem. Fuel pump overpressure is unlikely, but another possible cause.
What does the plug look like? That should be step one because you'd more than likely be running very rich. Other questions to help diagnose - how's it been running, any smoke out the muffler (if so, what color?), and is it hard to start? But pull the plug if you haven't already and maybe post a picture of it here.
Posted November 17, 2014 - 02:16 PM
If you cold started the engine and then did not fully warm it up, then keeping it warmed up for a minimum of 10 minutes, your oil will be fuel contaminated. However, it's also been found that due to the lack of a thermostat, the colder temperatures you currently have can keep the coolant temperature so low that the system never gets out of its warmup mode, which keeps the mixture artificially rich. You might try covering half of one radiator in the cold to see if that helps the matter.
Another possible cause is a leaking injector nozzle. If the injector does not close and seal, it will bleed off residual pump pressure into the intake when shut off.
Posted November 17, 2014 - 04:56 PM
Thanks for the replies!!! Rocker YZWR I definitely think there should be plenty of life left on topend im only a top C low B rider and I have a clam and smooth style of riding without much rev. I haven't pulled the plug yet but will definitely be doing so, but the bike runs great and has never showed any smoke out the pipe. Grayracer513 that's what I have found others suggested on similar posts that the cold weather maybe causing this. It really hasn't got that cold here in the times I've rode the bike it just started getting really cold in the past week and last time I rode was two weeks ago. One consideration I had was I thought about I always pull the fast idle or "choke" to start the bike and let it warm up for 30sec. or so before pushing it in. I only do this when its cold but maybe this doesn't help it running rich when warming up and could be a big contributor. Its a habit from having built carbureted bikes in the past that were very hard to start. I just hope this doesn't turn out to be a big issue. I just got rid of a 2011 crf450 because I had nothing but problems out of it and opted for a Yamaha because I thought they were bullet proof. Thanks!
Posted November 17, 2014 - 05:06 PM
The cold start knob doesn't cause the mixture to be rich during cold starts or any other time. It's only an additional air path, not an enrichment device.
Posted November 17, 2014 - 05:12 PM
Ok I wasn't sure just thought maybe that could be a contributor
Posted November 17, 2014 - 06:57 PM
So wouldn't the most likely "problem" be the injector leaking? the bike did sit for a long time before I ran it a few times and then changed the oil. I think the last time I changed it since last Saturday was back in mid September. The bike was apart with the suspension at pro-action had to get a set up im 6'5" and 215lbs so the stock springs and valving weren't cutting it. Therefore it had plenty of time to accumulate some fuel if it was leaking. Plus I broke my femur and dislocated a hip in early May and was out for a long time so when I do ride now I don't have any endurance and am lucky to put in a 12min moto without a break so any fuel in the oil wouldn't really evaporate and the bike never really does get warm because it doesn't run long and I ride it very smooth. Just trying to get a the best opinions you all have to give with all the info I'm a bit OCD and don't want to go through all the problems I did with a Honda with this bike. Thanks again
Posted November 17, 2014 - 07:59 PM
Posted November 17, 2014 - 10:55 PM
Posted November 27, 2014 - 08:09 PM
Posted November 27, 2014 - 08:11 PM