Petrol from the crankcase breather

Hi guys

got a problem, noticed my xj was smelling of petrol. Tried to start it and about a litre of gas came out the left hand pod filter.

Left it a day or so and tried to start it again. This time about 3 litres came out the crankcase breather!

Im assuming something in the carbs has failed and is letting gas pour straight through what should i be looking for?

Bike is an xj 550.

Thanks

Matt

 

The petcock is not working properly and letting fuel through and th needle/seats aren't sealing -- a very common problem or you may have it turned to Prime...and you will have to replace the oil with a fresh lot. Don't run it with fuel in th oil you could do serious harm. Plenty of posts on here about this problem, search and ye shall find...

 

something wrong with the float in that carb. the float should shut off. either incorrect float setting or rust is sitting on the float needle valve.

 

Cheers guys

So ive got 2 options either the float needle valve or the fuel tap.

guess it needs a bit of tweaking

 

If the bike was running/idling without any issues..i dont see why float should get stuck..check PETCOCK first and go from there. Like bushy said
drain and change oil after fixing the issue else again gas might mix again in crancase. If the bike was sort of running rough its a good idea to do a carb clean.

 

cheers buddy ill order a fuel tap (petcock) kit and rebuild it as soon as i can

I think a good carb clean is in order anyway, could do with it running a bit better so good chance to sort it all

 

be very carefull if you even think fuel is going into the crankcase pull the plugs turn it over . gas doesnt compress you will bend a rod or bust a piston

 

the float is what shuts the fuel off inside the carb. not the petcock.

 

Agreed but its been suggested that the petcock might have gone and the fuel has simply pushed its way through the carbs into the engine

I hope i havent bollocksed the engine because i did try and start it but i hadnt realised at this point that fuel was in the crankcases and it simply gushed out of the breather pipe so hopefully the pressure was released this way!

Oh well if its gone bang sure i can find another engine cheaply enough

 

Your problem is the result of a two-stage failure.

The petcock is not shutting off fuel flow when it should.

One or more carb floats are also not shutting off fuel flow when they should.

You need to fix, rebuild or replace the petcock; and investigate your floats. Could be crud, dirt, wear, out and out failure or just horribly misadjusted.

Also, change the oil, and plan on doing it again soon. Do not run the motor with gas-diluted oil or it will go bang.

 

my bike sat for 2 weeks with the switch in prime. yesterday it fired right up and went for a ride. it's nice to have it working like it's supposed too. but it's not what causes the carbs to flood out.

if my carbs are going to flood out. then i'd rather know about it while the bike is sitting and NOT find out when i'm on the road. (leaving the switch in prime once in a blue moon as a general test result)

if the bike floods out when it's sitting. chances are high it'll flood out when it's on the road.