97 SX 700 carb issue - dumping fuel out the vent tube

S

slednek

New member
Joined
Jan 20, 2004
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23
Location
Peoria IL
I have cleaned the carbs - all three, all the same way. Re-installed, after starting the sled, it started dumping fuel out of the vent tubes. I isolated the carb that is dumping, rechecked that the bowl float is working ( with me blowing through it). The valve shuts the air off like it should, the o ring is in good shape. These vents are half way up the side of the carb, what am I missing? Is the carb really getting that full to get to the vent tubes or am I missing a passage way?

Thanks in advance!
Dave
 

needle valve isnt sealing to the seat. although you can blow the floats shut, that alot more pressure than whats present by the incoming fuel. that o-ring on the seat can be real finicky as well. doesnt take much deterioration on it and hard to see with the naked eye. doesnt take much debris on the needle valve either and the tips do wear out.

quickest fix is a metric o-ring kit available at most auto parts stores. your looking for a 7.00mm id with 1.50mm thickness o-ring. if that doesnt fix it, time for a new needle valve set.
 
snowdad4 said:
needle valve isnt sealing to the seat. although you can blow the floats shut, that alot more pressure than whats present by the incoming fuel. that o-ring on the seat can be real finicky as well. doesnt take much deterioration on it and hard to see with the naked eye. doesnt take much debris on the needle valve either and the tips do wear out.

quickest fix is a metric o-ring kit available at most auto parts stores. your looking for a 7.00mm id with 1.50mm thickness o-ring. if that doesnt fix it, time for a new needle valve set.
Click to expand...

That is some great information snowdad. Is that for all proaction carbs or just the redheads??
 
There is a good chance there was a piece of something caught in the valve. When you had the carbs off, debris that was sitting in the carbs and hoses became dislodged and could have washed into the valve when gas first flowed in. When the gas came out and the carb was disassembled, the valve opened and whatever it was fell out. -Just a possibility.
 
Any chance you mixed up needles and seats? I have heard that they kind of wear into the seat so to speak and if you move needle to a different seat they usually will not seal very well. Could be just a rumor as I have never tried to make one leak.
 
I change the orings on all my sleds. They are getting 15-20 yrs old. After reading all the problems people have with carbs I think it might be a good idea to change the needle and seat too. Seems like it is much easier to just replace them the first time around. Also, it's a good idea to pull the gas tank, clean it and replace the filter. I also replace the fuel lines. Just do it all the first time and get it over with.
 
I just finished replacing the o-rings on all 3 carbs. This fixed the problem. What looked good to the naked eye was in fact bad. I could definitely tell the difference when I went to put the needle valve back in - it went in a lot more snugly.

Both sleds are up and running and ready to head to the UP.

Thanks again for all of the help.

This site rocks!!
 
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