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Discussion Starter · #1 ·
Hello to everybody!

The end of last year I didn't have the chance to ride my bike as much as I want. It was sitting for a few weeks and when i went out it felt like it is not working on a 100%. I changed the spark plugs and everything got smooth again. Few days after I noticed the oil is around L so I put some oil .... maybe too much :( and went for a drive, it was short like a few miles with no issue. I have left it for another 3 maybe 4 months and it was hard to start it up. Well I need to change the battery but not the point. Even with the choke it needed a few times to start and warm up.While warming up all sounded great. When it warmed up it started blowing from the exhaust pipe and blowing oil next to the air filter, it was a big leak. I have checked with a mechanic and I was told that it might be just too much oil. Note that after blowing lots of oil /maybe 150-250 ml/ I cannot see the level of the oil on the side because it is over the H , basically you can see that is toooo much. My question is can I drain the oil, put the right amount this time and try start it? The mechanic told me that it can also might need to change gaskets and some other thing. The problem is that this guy wants a lot of money just to open the motor without working on it and I am not sure if I can get scammed for a simple thing as too much oil and he starts changing thing I don't need. Also the oil was pretty dark too.

Thank you for any advice :)
 

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Hi @Vladimir Tanev and welcome to the forum!

I'd drain and refill with the proper amount. Run it for a bit to let any excess burn off and see how you make out.

If it continues to leak then yes you may have some damage that needs repairing.

You may find there's some oil in the air box as well as the catch bottle under the right foot peg (Most folks don't even know the catch bottle is there!) that will also require cleaning / draining.
 

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@Vladimir Tanev Welcome to the forum. Seems to me that you have overfilled the engine. Blowing oil into the airfilter means that the crankcase pressure is expelling the excess oil. As Obo said: drain it, and refill with the correct amount.
 

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Open up the oil fill plug and sniff the oil in the engine for gasoline. It is possible that you have a leaking petcock and you have gas in your crankcase, hence the oil level above the 'high mark'.
 

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Discussion Starter · #5 ·
Thank you all for the advices. I forgot to mentioned that after the bike warmed the sound from the exhaust was like a gun shots and the oil leaking was black. Do you think I should drain the oil and change the spark plugs before trying to start it :)
 

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Drain the oil, YES. Too much oil isn't a good thing, just like not enough oil.

I'd not change the plugs yet. You can inspect them, and clean with some solvent and a brush if they look oil covered.
My reasoning is until you get the proper level of oil and burn off the extra there's no reason for new plugs that might get fouled up in the meantime.

After you get it sorted out and it runs ok, then sure - new plugs are fine.
 

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Thank you all for the advices. I forgot to mentioned that after the bike warmed the sound from the exhaust was like a gun shots and the oil leaking was black. Do you think I should drain the oil and change the spark plugs before trying to start it :)
Again... Did you sniff the oil for evidence of gas? This takes roughly two seconds. Your next step would be to pull the fuel line from the petcock with the bike off to see if it is dripping.
Is your gearbox making more noise than usual during shifts?

I had a crankcase fill up with gas from a leaking petcock and one of the first symptoms was a shotgun blast coming from the muffler upon startup. That would be caused by the raw gas leaking onto the piston then traveling into the exhaust system through an exhaust valve.
 

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Whilst the mechanic is not wrong about the possibility, the excess oil you had in the crank highly unlikely to be so much as to cause such an amount of pressure to blow the seals. The blow-by pipe is usually for oil and fuel vapour that squeeze by the rings. The pipe routes it back to the intake and allows pressure to be relieved.
Changing the oil is always a good idea. No need to change the plugs again - just give them a clean with some high flash solvent.

I had a crankcase fill up with gas from a leaking petcock and one of the first symptoms was a shotgun blast coming from the muffler upon startup. That would be caused by the raw gas leaking onto the piston then traveling into the exhaust system through an exhaust valve.
Crank cases can fill up with fuel but not that common, and you can see the oil emulsified in the viewing window - like mayonnaise. A small amount of fuel in the oil won't matter too much. If the carb needle jet is worn or the float is stuck the fuel can continue to draw down from the tank. It usually goes back to the airbox side as the rear of the carb is lower than the front. Backfires usually happen with a hot engine and happens when unburnt super hot fuel reaches the oxygen at the exhaust tip. The airbox can pop though when the bike is cold. I'll have to look into that.
 

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Discussion Starter · #9 ·
Hey guys! I had the chance yesterday to drain the oil and it was very very thin and stinking of gas. The oil was going out like water so thin. A friend of mine suggested that the fuel pump might need to be changed :rolleyes:
 

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Kudos to @Zed7 for guessing right the first time!

@Vladimir Tanev there is no fuel pump in these bikes. It's gravity fed thru a vacuum activated petcock.

You've either had a petcock failure OR you've got it set to PRI (aka prime - which is on all the time) and one of the float valves in a carb has failed to close and that's overfilled the bowls and filled the crankcase with gas.

You can check the petcock by putting to ON or RES (reserve) and removing the main gas line (the larger one.) If gas comes out the petcock is bad and needs to be replaced. If no gas comes out then it's an issue with a float in one or more of the carbs.

If it's the petcock you are better to buy a complete new one vs a rebuild kit. There's not much to them...

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If it's not the pectock you'll need to inspect the carbs.
On the carb here's the white plastic float and the tiny valve that lets the fuel into the bowl when it get's low.

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Hey guys! I had the chance yesterday to drain the oil and it was very very thin and stinking of gas. The oil was going out like water so thin. A friend of mine suggested that the fuel pump might need to be changed :rolleyes:
There's no doubt your petcock is leaking or that, as Obo has suggested, you had left your petcock set to "PRI".
What you should do at this point...
Put bike on center stand.
Remove the tank and pull the spark plugs.
Pour an ounce of motor oil in each cylinder since raw gas has been leaked over at least one piston and washed away the lubricating oil.
Change the oil with the cheapest 40 or 50 weight oil and empty out the oil filter and replace the same one.
Then with the bike in fourth or fifth gear, turn the rear wheel in the forward rotation to move the cylinders up and down to lubricate the bores.
Replace the tank or use an auxiliary tank.
Now run the bike for about three or four minutes til the engine is warm. This is flushing the gas out of the engine and oil cooler.
Then change the filter with a new one and fill up with good oil of proper spec.

You will need to replace or rebuild the petcock, it can either be leaking through the tiny o-ring (#670 in the diagram above) or through the vacuum diaphragm. A new petcock is best since sometimes a rebuilt one that has leaked cannot be rebuilt regardless of how good the casting looks internally.
Your carbs also probably need rebuilding at this time but if the bike is otherwise running perfectly then you can try adding an inline fuel shutoff as a backup.
(I have an idea about this.)

Been there done that. TWICE! 😫
 

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Discussion Starter · #12 ·
Hey guys. The bike is in my friends garage and I don't have a lot of time to go there and check on things. I have checked yesterday and when the petcock in on ON or RES there is no leak. I remember that I have left it on PRI. Since I have lef it on PRI can this be the issue and do I still need to check the tiny valve in the carbs? :)
 

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Hey guys. The bike is in my friends garage and I don't have a lot of time to go there and check on things. I have checked yesterday and when the petcock in on ON or RES there is no leak. I remember that I have left it on PRI. Since I have lef it on PRI can this be the issue and do I still need to check the tiny valve in the carbs? :)
If your petcock is not leaking then you can get away with it but just remember, your petcock WILL leak at some point and you already know your float valves aren't up to the task.
You should buy yourself a brand new OEM petcock and install it or a rebuild kit and take care of the matter before it does leak.
These petcocks are getting old and eventually will all leak.

Installing a manual shutoff in the fuel line is a good idea but there is darn little room for one. I just rebuilt my carbs and unfortunately I wish I knew to rotate the fuel tee downward so that the fuel hose came out UNDER the carbs to make room for a shutoff.
Here is a pic of another bike I have with that arrangement. I was even able to fit a fuel filter.
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