FFFFF... Floats...

[X-Ray]

Hello Stou, make the measurement along the flat section of the float in #1, just make sure you have the carbs at around about a 45 degree angle so the floats so not have full weight pressing down on the needle valve.  I think also using a different length main jet needle in your photo would cause all sorts of issues, Id stick with the standard one.

[Pat Conlon]

Also I bought carburetors rebuild kit *like the one RPM website* I bought localy because they was available with one day free shipping. They are exactly like this one.....

......But this main jet needle is shorter than the one I have in those BS36. Do I need to keep my Mikuni needle or use the one in the kit?

Well, it appears that the aftermarket kit you bought is not *exactly like* the RPM kit.
The needle height difference between the kit and oem is significant.
That aftermarket needle looks to me to be waaaay too short.

I'll defer to the experts

[stou]

I know what is the problem with the kit. Like Robert wrote in my writeup thread, the carburetor I use are from late FJ1100 & FJ1200. I made a mistake and ordered kits for '84 FJ1100. So I will not use the needles from the kit. The main reason I ordered the kit is for the needles and seats, the #112.5 jets and gaskets. I was cheaper to order kits thans separate parts.

[stou]

I made a PVC rack like the one of X-Ray, very useful!

New jet kit and new needles and seat installed.

I installed the carburetors on the rack and made them at level. I did the tedious task for each carb of "check level/take notes/drain carb/remove the floats/adjust the floats/install the floats/fill carbs" and restart the procedure many times to finaly get the level at +- 3mm of the edge of the carbs body.





I installed the carbs back on the bike, get the bike outside... brrrrrr -5°C and installed the auxiliary tank. I started the bike with the choke and it was running not too bad, considering the carbs are not synchronized. But they started to leak from the bigs tubes and a little bit from the overflow tubes.

I noticed that once installed, the carbs are not at level on the bike. I used the level of the iphone and there at 6° angle down to the front. Can it be the cause of the overflow?

Also, I did a search on the forum but I didn't found exactly what are the 2 bigs tubes that are comming from between a pair of carbs?

[Pat Conlon]

Yes, there is an angle to the carbs, as you discovered. This 6* angle is increased even further if or when you raise the rear end for better handling.
The 2 big tubes are your float bowl vents, necessary to keep your internal fuel bowl at ambient atmospheric pressure.

Try setting your float heights at or 1mm above the maximum value. (i.e. make the floats as low as possible in the bowls) Don't measure the fuel level at the back of the bowl but at the middle of the bowl (on the side) with the understanding that the 6* carb angle (or higher) the fuel level will be higher at the front of the bowls (engine side) than at the back of the bowls.

[FJ_Hooligan]

That spec should NEVER be +3mm.  The fuel level must be -3mm or more BELOW the float bowl gasket surface.  

Do an extreme adjustment like -6mm and see if you still have problems.

My original carbs started seeping out of the small (choke circuit air intake) hoses and I never figured out why.  I jacked with them for weeks and replaced parts and it continued to seep.  I finally swapped to a new set of carbs and the problem went away.  Make sure your carbs are in good shape before you waste more time.

You can make this measurement when the carbs are installed if you place the tube in the middle of the side of the float bowl.  The fuel level will pivot at that point.

[stou]

Thanks Pat! 

Next Wednesday I'm going south for 2 weeks for a little bit of sun and warm weather. So the project will be put asside a little bit 

[Pat Conlon]

You're welcome stou  


David, didn't you try drilling a secondary vent like this?
http://www.fjowners.com/index.php?topic=7056.0

Shortly after Pete's above post, ~around the fall of 2012, I recall one of our old timers (I thought it was you) tried this trick and reported that it worked.

Our theory was that, with the back end raised, the fuel level was now higher in the front side of the fuel bowls and now covered the dip tube vent hole located on the front side of the fuel bowl. This secondary 1mm vent hole was now located well above the fuel line and thus, provided an air break which interrupted the siphon of fuel from the bowl.

Off to the catacombs I go searching.....tell Jannie I won't be home for dinner....

[X-Ray]

Yes good pickup. Hopefully no one ever measures 3mm ABOVE the gasket line, would be a fair amount of fuel flowing out those overflow tubes, 

[Sparky84]

Yes good pickup. Hopefully no one ever measures 3mm ABOVE the gasket line, would be a fair amount of fuel flowing out those overflow tubes,  

Mine seem happy to be at this level



But I really need to fit new petcock, when I switch mine to prime, it leaks from the tap I believe.

[stou]

Is this level is when the carbs are on the bike?

[Sparky84]

Is this level is when the carbs are on the bike?

That level on mine was carbs off and level on a bench.

[stou]

Kind of weird because mine was very good on level on the bench, but when I installed them on the bike, they leaked a lot.

[Sparky84]

I noticed that once installed, the carbs are not at level on the bike. I used the level of the iphone and there at 6° angle down to the front. Can it be the cause of the overflow?

Also, I did a search on the forum but I didn't found exactly what are the 2 bigs tubes that are comming from between a pair of carbs?

These 2 big tubes, did you break the carby rack at all to replace those o rings?
You actually only need to remove the outside 2, but necessary, mine leaked when touched.

They are the overflow pipes I believe.

[stou]

No I didn't replace those o'rings. But it was leaking through the tube, not by the plastic connector. Everything was nice and dry when I checked the level on the bench.