1996 gpx600r fuel in oil

[hornetmike]

just bought a project gpx600r, it starts and runs, but the oil smells of fuel ? the plugs were black and wet, what could be causing this ?
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[fiery tupp]

I would say piston rings ,see what others think & if so do a compression check to see wich cylinder, you may not have noticed with it being new to you & 3 pots running ok , Is it smoking more from 1 silencer ?
____________________
If you can't fix it with a hammer , use your head .

[temeluchus]

Probably one or more of the following:

Faulty fuel tap (vacuum not working, leaking)
Any of the float needles/seats are worn
Faulty float or improperly adjusted

This will cause the engine to flood. Petrol easily gets past the rings and into the oil. Sort out your fuel tap and carbies first before changing the oil. Its more likely to be the float needles first then the tap.
____________________
Some shite cruiser. Now with guns and FREEDOM!

[Kickstart]

Hi

I would go along with the above. Rings won't cause the problem (fuel getting into the engine will dribble past them eventually anyway). If the carbs over flow then a good chance the fuel will get into one or more of the cylinders. Carbs will over flow if there is a fuel supply to them (ie, faulty vacuum fuel tap, or you just left the tap on prime) and the carbs are not shutting the fuel supply off either (so worn needle valve/s or incorrectly set float height/s).

Could even be a vacuum fuel tap that is seriously broken and leaking fuel down the vacuum line into one of the inlets.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Ichy]

Just to add. Check the airbox. Sometime a breather from the engine will go into the bottom of the box. If any fuel gets in there, say from backfiring, it can flow back into the engine.

Personally I'd give it a good run first.

[hornetmike]

cheers for replies , will start checking tomorrow.

What can go wrong with fuel tap ?
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[Grav]

The rubber seal and/or the diaphragm in the fuel tap can perish depending on how long it has been stood.

As far as I can remember the GPX 600 doesn't have a mainstand so it will have been stood on it's sidestand for a while. Couple that with the aforementioned needle valve wear and you have a free flow of fuel through to the lowest cylinder. Does that make any sense?

Keith will know what I mean, he's better at explaining stuff than most folks, me included.
____________________
Dark Lord Of Custard

snigger.....

[hornetmike]

how do you test vacum tap
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[temeluchus]

disconnect the fuel and vacuum hoses from the carbs, leave them on the tap. Make sure the tap is set to ON.

If fuel is pissing out the seal is buggered.

If not, apply vacuum to the vacuum hose-syringe, suck on the hose or whatever. If fuel runs with with vacuum but not when the vacuum isnt present then the tap is ok.
____________________
Some shite cruiser. Now with guns and FREEDOM!

[hornetmike]

if its a vacum tap will there be two hoses on it ? ours has one.

plus if its not should run out in the on position ?
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010

[Pete.]

If you have only one hose it's not a vacuum tap. This being the case, it's most likely you have a non-sealing float needle and one of the carbs has overflowed. Fuel will have either got into the oil by filling the inlet tract and filtering past the valve and rings or flowing into the airbox and down the crank case breather.

The cheap cure is to always turn off your fuel tap when you switch off the engine. A more expensive cure is to replace the needles and/or seats. The clever cure is to drill out the seats slightly so the needles seat further down the taper on a part that is not worn. You will have to re-set the float height if you do this.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[hornetmike]

Thanks for your help, we stripped , cleaned and rebuilt the carbs adjusting one of the floats. Changed the oil and cleaned up the plugs, re seating the needles is beyond me for the time being so will turn the fuel tap off after use.

Thanks for your help, proved a point with my mate about how useful this forum is.
____________________
87 Honda CG 125 - 97 ER5 - SR 50 -81 Z250- 96 CBR 600 F- 94 GPX600R 88- GPX 400R- 87 GS 125 - 2006 Honda CB600F- 2003 ER5 - Honda CBF 1000 2009 - Honda CBR 600 RR 2011
Current BMW R1200GS 2010