petrol in the oil

i had carbs synced recently and changed oil / filter /plugs etc
noticed im now getting petrol in the oil, what causes this? i think it would be bad to use it like this.
also cant see an off position on the petcock, down is on,rearward is prime forward reserve ithink,cant see an off position
83 xj750 seca, cheers for any info

83 xj750 seca

04 suzuki vs 1400

 

You have a problem with one or more floats/valves. The carburetors are over filling and leaking into the cylinders where the fuel soaks past the rings and ends up in the oil.

Your fuel valve is an auto shut off. In any position other than "PRI" fuel should not flow through it unless the engine is running. "PRI" is only used to refill empty carburetors after service or storage.

The shut off on the fuel valve is a safety to protect you if you have a float/valve problem. Unless you've left it set to "PRI" you have a problem there too - it's not shutting off.

And yes, you should not run it until you fix the problem and replace the oil and filter.

 

cheers for that will have to get them off

 

Float levels: http://www.xj4ever.com/setting%20fuel%20levels.pdf

Vacuum operated fuel valve tech: http://xjbikes.com/Forums/viewtopic/t=25058.html

Carl is correct in that your problem is in the carbs. A faulty petcock is only an "enabler." But it's nice to have everything working as it should.

You're also going to need to make sure your valve clearances are in spec so that your freshly serviced carbs can be properly adjusted once reinstalled on the bike.