General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: Valentinik34 on June 17, 2021, 05:46:24 AM

Title: FJ100 3CV choke problem
Post by: Valentinik34 on June 17, 2021, 05:46:24 AM
    I'm just restoring a 3CV fj1200 and the carbs were badly clogged. i thought i'd cleaned then thoroughly  :Facepalm:

It is really hard to start and if you try choke it instantly kills it.  When after many minutes on the starter motor it does go and the motor gets warm then it runs like a dream.

Not to sure where to look for the blockage

Thanks in advance and enjoy the day  :good2:

Title: Re: FJ100 3CV choke problem
Post by: Waiex191 on June 17, 2021, 07:05:36 AM
There is a passage in the bowl that feeds the choke circuit. I'd look there.  There is a tiny orifice which you can't get to, and the passage is not straight.

Hey all,

There is the brass tube that sticks out of the carb bottom and seems to go up to the enrichening circuit.  On the bottom it sticks into a hole in the bowl.  It seems there is a tiny orifice there, a cavity underneath it, which is connected to the interior of the bowl.  I'm assuming the fuel slowly bleeds past the orifice to put a slug of fuel around that brass tube, for initial startup.  What is a good way to clear this?  I couldn't get my safety wire through it.  Nor could I blow it out with various solvents or compressed air.  The tube, the hole it goes into, and the passage to the bowl are all in line in this picture - from bottom to top.

I am thinking if there is no other good option, I could drill up from the bottom inline with the brass orifice plug, clean out the cavity, and then put a #4 screw or something small there.  I also wonder if that same problem exists in my GN400 Mikuni carb - I can't seem to get it to kick start when cold, I have to bump it.

From page 2 of my thread: (