carbie problems

[ozcraig]

Hi' I have a 98 gtx ltd, The carbie I have is a mikuni BN-46i-46.
My spark plugs are showing a bit of oil around the outside of the plug, but around the electrode it seems to be running a little lean.
I have turned the the high end screws about two turns out, when I believe they should only be one eighth of a turn. Aslo the low end screws are about three turns out.. The carbies are still running a little lean..
If anyone has any ideas it would be great...
Thanks Craig

 

[seadoosnipe]

Too much....

Yeah, you got your high and low end screws out to far. With that much fuel, you should be choking out, plugs dripping wet.
I'm thinking you may not have a carbie problem. Well, you didn't before you adjusted the screws out to far. I think your problem may be in your reed valves. Have you done a compression test on the cylinders. If not, you'll need to do that too. Get me the results on the compression test as soon as you can. Are you still riding? Does it still have good bottem power?
It's been a while since I read up on them, I'll research my reasons and get back to you later this afternoon, my time; night time on your end.....
Welcome to the forum...............:cheers:

MORE INFO:....the low speed screw should be 2 turns out, +/- 1/4 turn. The high speed should be 0, with the black plastic cap on. Do nut attpempt to remove this cap to make adjustments. This is preset and shouldn't be moved any further than the 1/8 turn allowed by the cap.
Have you checked your fuel filter for signs of water and/or blockage? Have the carbs been removed recently? If so, check to see that they are tight and not sucking air. The fuel return line also has a an orifice in it, have those lines been modified?
It seems like your either sucking in to much air or your fuel system is dirty. The oil your talking about I believe is a build-up on the cylinder walls from your turning it over, although I wouldn't rule out seals or anything that can be attributed to your oil injection/lubrication system.

 

[kustomkarl]

:agree: Right on seadoosnipe... you hit the seadoo right on the head...
Karl

 

[ozcraig]

thanks guys

once again I appreciate your advice, from both you guys..
I have spoken to a few people,, one advised me to change the main jets to give me more adjustment, another advised me to check the popoff pressure and the other advised me that before I do either of the first sugestions was to check the pressure in the fuel tank
They advised me, that when I opened the petrol tank cap, I should hear the pressure release and if I don't it could just be the pressure valve..
Given that this was the easiest to check, it was the first. As it was I could hear any pressure release when I opened the petrol cap,,{ the ski was sitting in the sun}..
Can I have your thoughts on this. If you agree about the valve, can you tell me which valve and where to find it..
Once again thanks guys.
Craig

 

[kustomkarl]

It sounds like the vent in the fuel tank is plugged and causing it to over pressure the fuel system. IN the sun gas vapors will expand and cause it to over pressurize the system. Follow the vent line from the fuel tank to the valve and see if it is clogged. I quick test is to open the cap and go for a quick run, Stop, shut it off, and open the cap again to see if it is pressurized again. Than check the vent for blockage if it has lots of pressure.
Karl

 

[ozcraig]

Sorry karl, the last thread should of read.
I couldn't hear any pressure when I opened the petrol cap
thanks

 

[kustomkarl]

Craig, did you adjust the carbs as seadoosnipe advised? With the high speed and low speed screws set at tha correct settings how is it running now? Start with the correct settings and go from there. That way we will have the basics covered and can go from there.
Karl