needle and seat part difference,s

[1wormsway]

You are working to hard...

You can just use your old brass seats, they never wear out. It is the rubber tip of the needle that wears. You can use the new o-rings from the new seats on the old ones and then use the new needles.

And to answer Andy's question; the needles are all the same, it is just the hole size that changes. Now, with that said the float height had to be set differently as the needle goes deeper into the larger hole to seal.

Randy - RPM

I know this is an old thread, but do not feel the need to start over with this one. Just would like to put my two pennies in for anyone whom might happen along looking for this particular info.  Currently have both parts in front of me, ie. 25G-14107-23-00 and 3CF-14107-15-00 and I find no discernable difference. This being both on a visual level and measuring by feel with the blunt end of a drill bit. There may in fact be a micro difference that I am missing without having at my disposal a more precise means of measuring, although I have never so much as had to reset float level when switching from one part number to the other. I believe the part # difference is in # alone and was probably a way of feeding the dealerships more stock, or just making older # obsolete. Has any body tried to order the 25G's recently ?

[racerrad8]

I know this is an old thread, but do not feel the need to start over with this one. Just would like to put my two pennies in for anyone whom might happen along looking for this particular info.  Currently have both parts in front of me, ie. 25G-14107-23-00 and 3CF-14107-15-00 and I find no discernable difference. This being both on a visual level and measuring by feel with the blunt end of a drill bit. There may in fact be a micro difference that I am missing without having at my disposal a more precise means of measuring, although I have never so much as had to reset float level when switching from one part number to the other. I believe the part # difference is in # alone and was probably a way of feeding the dealerships more stock, or just making older # obsolete. Has any body tried to order the 25G's recently ?

Jeremy,

Let me take this time to correct information you have posted based on measuring with the proper tools, the correct information about the part numbers and the experience associate with FJ carburetors.

This has been covered several times, but since you have brought up this old thread, I want to make sure it is posted again.

There are in fact, two different needle seats for the FJ carburetors depending on if they were early model gravity or late model fuel pump feed. The difference is the size of the hole that is the inlet supply for the fuel. Unless you have a number/letter drill bit set that is in 1000ths of an inch, you probably cannot measure the difference.

I have both letter & number drill bits as well as a dial caliper that I use for measuring. I have measured them long ago to determine the actual difference of the seat which is;

Gravity; 2.3mm or .090"
Fuel Pump; 1.5mm or .060"

If you were to remove the screen from the tip of the needle seat you will see the numbers stamped into the body indicating the size of the original Yamaha seats. Here is a 2.3mm seat, sorry I do not have a 1.5mm seat readily available.


I personally can see the difference in the hole size just by looking at them, but I took a couple of pictures so you hopefully can see the difference with the zoom of the camera. The 2.3mm hole is on the left.


Closeup


You can also click on each photo and that will take you to the Photobucket page and allow you to zoom in even closer if needed.

Now, the difference in the size of the hole means the needle valve will not sit as deep into the smaller hole and deeper in the larger hole. So, the floats should be adjusted according due to the difference of the holes size & contact point upon the needle.

The reason the smaller orifice seat is used with the fuel pump version bike is the line pressure applied to the tip of the float valve. If you try and use 2.3mm seats on the fuel pump bike they usually bypass the seat and flood the carburetors.

Finally, the actual difference in the part number is at the back of the number not the beginning prefix; -15 or -23 which is the size of the hole of the seat.

I hope this clears up any doubt you have that there are in fact two different needles seats that are required for use on the FJ depending on the application they are used on.

Randy - RPM

[FJmonkey]

I concur with Randy, I switched a FP set of carbs over to GF and forgot to check the float height.  Took the carbs off and pulled the bowls, and reset the float height....

[movenon]

+1    

George

[1wormsway]

Randy,

I stand corrected. Two different size seats. Thanks for the clarification on my mistake. Been awhile since I had to deal with needle and seat. Old parts were mislabeled and upon searching further found the 1.5's. Yes there is an obvious difference.  Appreciate your sharing of knowledge and will look forward to you correcting me again, probably sooner than later. Cheers, and yamaha ha ha to all

[Pat Conlon]

I will copy Randy's most excellent post and place it over in the Carb. Files for future reference.

Thank you Randy.