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84 fj1100 won't accelerate (possible leak)

Started by 996ItsNice, February 16, 2025, 12:45:16 PM

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996ItsNice

Hi guys, I'm new and this is my first post here, nice to meet you all. Sooooo, sometimes ago i bought this bike from a local guy. Only had to change the battery and took it home. The bike was running a bit rough at lower rpm, but overall it seemed in good condition. After a couple of weeks (a took some short trips) I decided to clean to carbs but first I changed oil and air filter, new oil and new spurk plugs and fresh fuel. After that i put back on the cleaned carbs and the bike wouldn't run lol. So I double and triple
checked the carbs and it seems to be fine. Now the bike idles but only with choke on, but when I accelerate it either dies
or make like weird metallic from the right side, like in the
video. ( https://www.reddit.com/r/motorcycles/s/XriUMadb6y )I also noticed a weird leak coming only from the right exhaust
of the bike which seems to be water. I suppose it is a vacuum leak so I was thinking about the mix/idle screw gasket or the intake manifold. I already checked and all the diaphragm seem to be working .Before giving up and going to a mechanic I wanted to hear more opinions. So what do you guys think? Thanks all for the attention
Ps. I'm not an expert at all lol so if I made some errors pls be mercieful :dash2:

Pat Conlon

The 1984 FJ1100's have a vacuum operated petcock...so,

1.   ⁠Did you hook the vacuum line back up to the petcock? The petcock will not open until the vacuum from the engine opens it.
2.   ⁠Do a suck test on the petcock, see if it opens. a) Disconnect the fuel line from the carbs b) connector the vacuum line to the petcock and leave the other end of the line open c) suck on the vacuum line, see it the petcock opens and gas starts flowing.

Running only on the choke means your pilot jets and/or idle circuits are not clean.

Check to make sure your fuel line is routed correctly and not pinched. See my sig. line below.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

red

Nice,

Another poster mentioned his issue with the gas tank vent in the gas cap.
If you open your gas tank cap, does the bike run any better?
As Pat said, you may suspect a fuel line is pinched/kinked.
Did you change the fuel float settings in the carbs?
You may have dislodged some sediment in the fuel lines, which could be clogging the idle circuits now.
Please keep us posted.
Cheers,
Red

P.S. Life is too short, and health is too valuable, to ride on cheap parade-duty tires.

996ItsNice

Hi guys, sorry for the wait, it's been a while but I finally figured it out.
So, apparently, my problem had nothing to do with air leaks or the carburators, the problem was some burnt wires (as you can see in the photos). So basically the bike was running on 2 or 3 cylinders. Almost surely I had no spark.
The burnt wires that I had to rebuild  were the black (it was good but i accidentally cut it while removing the sleeve), yellow/black, red/black, brown and the grey wire.(I would like to know from somebody what is the purpose of each wire :ireful: )
I bought an "industrial wire"(the blue one) and an electric connector kit with sleeves and since I'm not electrician I had to figure out how the reattach the wires in the proper way. Each wire of the bike has 20 copper strings inside but the diameter seemed to be half of the ones that I bought (the blue cable) so instead of using 20 strings I only cut 10 from the new wire and attached to the bike strings. Finishing the work with the heat shrinking sleeves. Afterwards the bike finally ran almost "properly", at least I could enjoy a nice trip on the highway. The bike still has some difficult at lower rpms but I still gotta sync the carbs (just bought the carbtune tool and waiting for the delivery).
That said if you have any questions on how I rebuild those wires or if you have any suggestions, or another method you would've use to resolve the issue, I'm all ears.(I'm not mechanic or electrician so I surely made some mistakes). Thank you all  :good:

JMR