[fiddlemahn]

I was adjusting my chain tension the other day when I noticed that my oil level appeared to be completely overfilled in the sight glass. The last time I checked my oil level was about a month ago when I changed my brake pads. The oil level was in the middle of the window at that point (roughly 800 miles ago). When I opened the fill plug, the crankcase reeked of gasoline. What could be the cause of oil dilution like this? Lately, I have noticed that the bike has been running fairly rich and it has been backfiring more often during engine braking. My fuel economy also sucks and seems to be getting worse. I have read that injectors can become gummed up and stick open, causing gas to leak down into the cylinders while there is residual fuel pressure. Has anyone else on here had this problem? 2005 SV650S with ~28,000 miles TIA.

 

[Salty Sway]

Don't start until you have drained the oil/gas mix! Also change the oil filter.
What you have heard is likely the culprit, when things start going bad wouldn't that be the time to start looking at the problem? Fuel mileage down & backfiring were signals something is wrong. Most prople will advise you to change the oil and filter a couple of times to make sure the gasoline is gone. An overfilled crankcase can have a negative impact on a lot of internal parts.

 

[VAFish]

My only experience with that much gas in the oil was due to leaving petcocks open and stuck float valves on carbs.

But on a fuel injected bike there is no petcock or float valves. Seems like it would take a lot of starts and stops to get that much gas leaky by the fuel injectors.

 

[golden chicken]

It HAS to be a leaking injector. If it leaked anywhere else it wouldn't make it into the crankcase.

 

[OfirMX]

Yeah, only the injectors can lead fuel right into the crankcase. But it's still odd, IMHO the only way it could have enough flow to actually flood the engine would be if the injector is stuck open WHILE the bike is running and there's pressure coming from the fuel pump. But the bike would have had to be running like crap for a while and you would have definitely noticed it.

Please keep us updated... I'm intrigued.

 

[TeeRiver]

What Ofir said.

Gasoline in the crankcase happens all the time on the carbureted gen1 SV (a stuck petcock in combination with leaking float valves), but it is hard to flood the crankcase on a fuel-injected bike.

It is easy for the oil level to move if the bike is not perfectly flat and level. Maybe double-check over the next few weeks? Combustion gas blowby is normal too, so there will typically be a strong smell from the crankcase.

Keep an eye on it for sure, but I would be surprised if the high reading is due to gasoline.

As for anyone else having this problem, I've never seen it posted here on SVR.

 

[fiddlemahn]

UPDATE:
Last night I changed the oil. Other than a slight amount of goo on the oil plug magnet, there did not appear to be any glitter or metal shavings in the oil or the filter. The oil still smelled strongly of gas, however it did seem that much stronger than the previous 3 oil changes that I have done on this bike.

I have read that condensation can accumulate in the oil if the bike is ridden a bunch of short distances in a row. I have been mainly commuting to work lately, which is about 10 miles, and the bike rarely gets hot enough to boil off condensation, as it usually runs around 187F when cruising (which could be due to my rich A/F ratio). The water in the oil had to also be mixed fairly well, as I had just ridden the bike and it had not yet separated. After I changed my oil, I let the bike idle until the fan came on around 212F. I then let it idle at that temp for about 5 minutes to boil off any residual condensation. After the oil change I filled up with a fresh tank of ethanol-free premium and put in a whole bottle of Techron fuel injector cleaner with hopes of cleaning the injectors.

Overall, I think I had a few problems here:
1. I am getting a fair amount of blow-by in the cylinders. The bike is 17 years old and has 28,000 miles, so that is to be expected to a degree.
2. My fuel injectors were becoming gummed-up, which would explain the gradually increasing rich air/ fuel ratio, and potentially causing fuel leakage.
3. I had excessive condensation in my crankcase, causing the oil level to read high when held level (on a lift).

Moving forward I will be keeping an eye on my oil level, rich smelling exhaust, and overall health of the engine. I am interested to see what affect Techron has on my injectors, if any.

 

[TeeRiver]

Thanks for the update, fiddle. These SV650s last forever. With 28k on the odo, I think you will be enjoying your bike for a long time to come. It sounds like you take good care of it.

Welcome to SVR!

 

[sv650bklyn]

My two cents:
Our SVs HATE not being ridden long and often enough.
Most of the weird engine issues, sounds, vibrations, etc. I have experienced with my now 62k mile and 16 year old bike is when I didn't take it out for a proper long ride every once in a while. The longer the better. The best my engine ever ran was after a 4k mile road trip.

Your bike has been ridden less than 1,700 miles per year. You're also riding it very short distances most of the time. My layman's advice is to give it a proper ride once a week, preferably spirited using the entire RPM range. I'm talking at least 30-60 minutes with the engine at optimal temperature. Idling for a few minutes won't do the job.

Techron may help, but don't expect miracles. The premium gas you used usually has additives that perform pretty much the same function. Even regular 87 gas (which makes more power in the SV than higher octane gas) from a top tier gas station should have enough detergents to clean up your fuel system. A ride using two or three tanks should work wonders.

 

[OfirMX]

Wait, Sascha, you are saying we need to go out and actually ride these things?
I need to rethink my life 🤔