Carburetor Fuel Line Question - Stock vs 1250 Legend for FJ1200?

[86FJNJ]

(Newbie with a 1986 FJ1200 with F1r slipons)

The stock carb that came with my bike has two fuel lines that come out from the carb into a "Y". I recently came across a carburetor for sale that I was told was built for a 1250 Legend but it was thoroughly cleaned and in very good condition and I thought the price was very fair so I snatched it up figuring it may be a good backup for me to have as I try to get my FJ running and wasn't fully sure of the quality of my stock carb.

I noticed on the backup carb that it has one fuel inlet in the middle (as opposed to the two that my stock carb has). Can I run this "1250 Legend" carb on my FJ with this single fuel inlet? Would there be any issues from that? Also, I took the float bowls off and the main jets were 120, but I don't know anything else about the carb except that it's immaculate inside and sat on a shelf for 5 years. If this was set up for a 1250 legend would I need to do anything else to use it on my FJ?

As always I appreciate everyone's help. I can take better photos if needed.

[Pat Conlon]

Two flavors of FJ's: '88-'95 Fuel pump FJ's and '84-87 Gravity fed FJ's.

The center inlet carbs are used on the fuel pump equipped FJ's and because of the pressure exerted by the fuel pump, those carbs use a smaller 1.5 float needle seat.

The dual feed carbs (like your oem) are set up for gravity feed and uses no fuel pump. This gravity feed results in a lower fuel pressure and thus uses a larger 2.3 float needle seat due to the lower line pressure.

 Can you run the fuel pump carbs on a gravity fed FJ? 
You can try but you might get some fuel starvation issues, like @ low gas level in the tank, high rpm's.

The proper way is to get a new set of bigger 2.3 float needle seats and put them in your fuel pump carbs and convert center inlet over to dual inlets. RPM has all the parts you need to do this.
1) 2.3 Gravity Float needle seats: http://www.rpmracingca.com/proddetail.asp?prod=3CF-14107-23&cat=24
I do not recommend reusing your old 2.3 float needle seats. Get new ones.
2) Get fresh o rings and reuse your old dual fuel inlets on your new carbs.
3) You will remove the fuel pump single fuel inlet and replace it with this plug:
http://www.rpmracingca.com/proddetail.asp?prod=Carb%3ACarbFitting&cat=24

Cheers.   Pat

[86FJNJ]

Thanks Pat!

At the moment I am just trying to get the bike idling good in my garage to ensure the engine is up to snuff before I take next steps. I had it running on starting fluid for about 5 seconds so that's a good sign. I need to actually have it running for a bit to warm it up so I can check compression. If compression is good I'll send the carbs to RPM for a professional job while I concentrate on the other things that need attention.

Since my stock tank is coated with rust inside I found a 1990 3CV FJ tank clean on the inside so I may try to use that in early stages before I get the stock tank usable.

I'm guessing I can't easily add a fuel pump to my 86? Seeing as how I now have the carbs and tank for that already just curious if that is possible.

[Pat Conlon]

I'm guessing I can't easily add a fuel pump to my 86? Seeing as how I now have the carbs and tank for that already just curious if that is possible.

Go ahead and run those carbs...you should be fine for testing purposes. You need a step down adaptor for your big fuel line for the smaller hose used on the fuel inlet on the pumper carbs.

Adding a fuel pump is a mod unto itself. It is a mod I want to do on my '84 gravity FJ.
Why? There are two advantages to a fuel pump:
1) I can run a real fuel filter on my fuel line, something I can't do on my gravity fed fuel system because the filter becomes too restrictive, impedes fuel flow. Our fuel tanks aren't getting younger and a real fuel filter will capture a lot rust flakes before they get to the carbs.
2) The gravity flow bikes use a vacuum operated petcock that, sooner or later will fail. A fuel pump FJ uses a simple straight on/off petcock with none of those vacuum shenanigans. The pump itself is the on/off on the fuel system.
To convert my gravity bike over to a pumper I need to do 3 things
1) Buy a Yamaha oem fuel pump...No Chinese eBay shit! Ask me how I know this....
2) Convert my gravity flow carbs over to the smaller 1.5 float needle seats (opposite of what you are doing)
 The line pressure from the new fuel pump will push open the floats on those larger 2.3 float needle seats and flood the engine.
3) Install a fuel pump safety switch that shuts off the fuel pump when the engine rpm's stop. https://www.classicindustries.com/product/re12003.html

This is on my list of mods...I've been meaning to do this for awhile...

Cheers Pat

[86FJNJ]

Thanks Pat! I am very interested to convert my gravity 86 to a fuel pump for the reasons you mention. I already have the carbs for it and I have the gas tank for it. Are you aware of a thread that has a step by step walk through of exactly how to do this? Where to add in wiring, does the fuel pump need a relay or fuse? This is all stuff I'm not familiar with but could do it if I was able to follow along somebody else who already did it.

[Pat Conlon]

Yes, you would need a 12v 10 amp spst relay controlled by your key on ignition circuit. The fuel pump would be powered by a dedicated home run to the battery (w/10 amp fuse) and fed thru the relay then to the fuel pump safety switch, then to the pump.

When I do this mod I'll take pictures and create a post over in the Modification Files.

[86FJNJ]

When going to pod air filters and shimming the main needle where does the shim go? Does the shim go on the lower part of the needle so the shim sits between the float and the big donut on the top of the needle which then pushes the needle up slightly?

[RPM - Robert]

This reads like you are referring to the float needle.

The main jet needle is in the slide. The shim goes between the circlip and the white or sometimes stained yellowish brown plastic locator.

I can send a pic Monday if no one posts on up this weekend.

On the 1250 carbs you will need to determine if it has stock needles or someone else's main jet needles.

[86FJNJ]

The carbs had custom hank scott needles in it so I replaced those with the ones from the stock carb. I ordered the needle shims and put them on the main long needles that mount inside the slide I put the shims on the needle then put the needle into the slide, then the little washer, than spring, then that top metal piece with the two screws. If the point of the shim (when using pod filters) is to raise the height of the needle I think what I did was the proper way to do it but that's what I wanted to check with the group on.

[86FJNJ]

I understand now and corrected it thanks for the help