My friend just bought an 88 250R. It leaks gas out the overflow. We have adjusted the floats several diff. ways. Could it be a bad float needle? We may just end up swapping a '00 CR250 carb on it and see how that works.

Any suggestions greatly appreciated.

 

It does sound like your float might be sticking. Mine did that intermittently. I ended up doing some major upgrades to my R, one of which was going with a new 38MM Airstryker carb which of course solved that problem.

 

If I remember correctly, the float height should be .630" from the base of the carb (where the float bowl mounts) to the top of the float (if carb is upside down). Remember, the metal tang on the float assembly that compresses the float needle is only supposed to touch the spring loaded needle, NOT compress it at this height.

If the float height is correct, tear the carb apart, and wash it thoroughly with hot soapy water, and blow it dry while at the same time blowing out all of the air and fuel passageways.

Check to see if there is a ring worn around the plastic tip of the float needle. If there is, the needle is bad and needs to be replaced. If not, you may have a piece of dirt, or crud in the seat that is not allowing the needle to seat properly.

The 250R's don't have removable float needle seats, so if all this so far has not corrected the problem, and the float needle is good, try this;

If you have a friend who is a machinist, or knows how to safely operate a metal turning lathe, you can make a tool to "lap" the float needle seat and remove the oxidation that commonly builds up on it as it is only made of brass (oxidizes easily).

Simply find a piece of round stock that will fit down into the needle seat area without binding up in the hole. You, or whoever is qualified, can turn an angle on the end of the metal rod (tool you are making) that will closely match the angle on the end of the float needle.

Polish the rods tip, apply some lapping compound to the tip of the rod, and spin the rod back and forth against the seat until you have lapped the oxidation off of the seat (it should leave a shiny ring in the seat where the oxidation was removed).

AGAIN, THOROUGHLY clean the ENTIRE carb with hot soapy water to wash out the lapping compound (you don't want this inside of your motor!).

Re-assemble carb and float/needle.

If this has all been checked, and done correctly, there will be no more leaking.

And last of all, buy a manual for the quad. They are invaluable![img]i/expressions/face-icon-small-wink.gif[/img]

 

This is his second R, and we already have the manual and know about the .630" stuff. Nothing seems to be working, it has already been torn down and cleaned. The carb has obviosly been honed out by a pro. It's as smooth as glass, and measures out to 40 mm. This kid had a '00 CR250 motor in a 250R frame before, and still has the carb off of that motor. I think he'll end up just puting that carb on it, but it would be nice to have a spare. All that we haven't tried is the "lapping" process that you mentioned 2fun, and replacing the needle. We'll give that a whirl.

Thanx

 

Ok. Be sure to let me know if the "lapping" works out.
I had the same problem on TWO PJ carbs, and the needle was ok.
Lapping the seat is what did the trick![img]i/expressions/face-icon-small-happy.gif[/img]