I am having problems with gas getting in the oil on my 1988 or 89 Suzuki LT-F4WD. I replaced the needle and seat in the carb but it still has gas getting into the oil. To me the carb is higher than the tank so I cannot see it syphoning from the tank to the carb. It has a Mikuni carb (19B50?).
Any suggestions. Someone said that maybe it is leaking past an "O" ring on the choke.

 

The fuel is getting in there while it is sitting or running?? If it's the latter that one has a fuel pump, so the position of the tank wouldn't make any difference.

Your pump may be putting out too much pressure and blowing fuel past the needle valve. Or if the engine is hard starting you may get fuel past the rings while trying to start it.

How much fuel in what time frame are we talking about and what does the plug look like?

 

I really don't know if it is getting in while sitting or running. I guess I could check this by turning off the fuel switch when I am not using it. Maybe I could use a dip stick method.
The unit is harder to start if it sits a week or so, so I was assumming that the carb was empty on fuel and it took awhile for the carb to fill up. If it just sits a hour , 1/2 day or even over night it generally fires up instantly.
I do not know exactally how long this takes but I have drained the oil several times in a summer. The first time I found gas in the oil there was so much gas that the machine was running good while I was using it, and when I shut it down, it would not start till it cooled right down. I do not have the trouble of it not starting now but I guess that is because I drain the oil frequently.
I hardly use this machine, it is mainly used for just a 5 minute trip or less. I would estimate that I put maybe a max of 100km (60 miles in a season).

 

Unless you have a lot of faith in the float being good, I would replace it with the needle and seat. You can verify its buoyancy by sitting it gas for about an hour, but even then you have a range it could still float and not do the job. I'm saying this assuming it's the fiber type.

Brass floats are a little different to work with.

 

I was 2 summers ago that I replaced the needle valve and seat I do not recall if the float was metal or composite

 

A lot of the Mikunis have the fiber job for a float. If it hasn't been changed in the last five years, it would be overdue.

If you wanted to go to the trouble you could put an inline check valve (one way to the carb) as low in the line as you can before the fuel pump. That would keep the fuel from bleeding back down the line. The would help the hard starting when it has sit for a while.