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Help with 2011 drz 400 won’t stay running

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hello all:

2011 dr400 started out with the crankcase full of gas “thing” when I lent it out, and he put it on prime. Drained crank, change oil, never put on prime position and all is well. Then it starts running shitty, craps out completely, not firing  at all at anything above a tiny bit of gas. On a hunch, because it acted like this when the gas thing happened. So I pull that little round stator cover cap, and drain a huge amount of oil out.........now runs perfectly. So draining the oil from there solves something that felt exactly like a carb problem! Imediatly.........until it fills up some more, and starts running progressively worse, until barely running again. Drain, and it runs perfectly, and I am good for another 20 km. I am leaving oil behind me that would make a Harley rider blush! But as per other similar posts......there is supposed to be oil in there......but this much? Anyone?

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How much oil did you fill the crankcase with? It only gets 2 qts.

There may also be another common problem with the carb. The o-ring under float needle seat. Over time it deteriorates and turns brittle which in turn causes fuel to leak past the needle and flow into the crankcase, thinning the oil. If your oil is thin and watery this may be the cause.

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Thanks so much, I am going to drain all the oil, and start over. No gas in the oil this time tho. Stunk of it before, not now. I bet I just have too much oil in there!! What a relief.

 

thanks again

steve

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Me me me…I want to answer this one…I think it is probably easy…ha ha.  
 

Simply leaving the petcock in PRI does not flood the engine with fuel. With a fully functional carb float the float bowl fills normally, which causes the float to rise and the float needle seats in its seat and shuts off the fuel. It is only in the case where this float needle fails to fully seat that the fuel continues to dribble into the float bowl, then overflow into the carb throat, trickle down the air passage and drip into the cylinder, drip onto and past the piston, and thus fill the crankcase.
 

the fact that you had fuel contamination after leaving it on PRI indicates that you had an operator error AND an issue with the float bowl valve. 
 

this problem has advanced to the point now that even when running the engine with the petcock in ON fuel is flowing into the float bowl until it overfills which causes extra unwanted fuel to run up into the carb passage and get sucked into the incoming air, which causes an ever richer mixture until finally the poor engine is flooded into silence. 
 

your float has sunk, or the float bowl needle valve or seat is damaged and this system is failing to control the fuel flowing into the carb. This is easily rebuildable. 

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Btw, don’t drive the bike til you fix this. All that extra oil is not oil, it is fuel diluted oil, which is a crappy lubricant and will lead to engine damage. Once you fix the carb, change the oil and filter again. 

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Thanks for all of this.  Will get that carb off and needle and seat sorted. Change oil again. This present oil does not smell gassy, but I get that the carb is available to have this happen all over again, and cause running issues. Really appreciate the help.

 

steve

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You should also check the black canister above the carb: it is to capture oil and fuel vapours from the crank case and return the liquid oil back into service while directing the vapours to the carb to be burned. It may be filled with fluid if you had big contamination’s.  

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Yes, I read about this thanks. 
 

checked the bike just now after my aborted attempt to use it the other day. No oil showing on the dipstick, even from fully screwed in😥🙄😬

it was overfull 6 KM ago? When I ran the bike, there was a mighty wind coming from that stator inspection port, as well as a constant flow of oil mist, and raw oil dribbling out.  Is it possible the oil is not being returned to the frame?

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