Fuel Mileage Woos

[aviationfred]

I purchased my current FJ a little over a year ago. The day after I made the purchase, I set off on a 2500 mile trip. From the very first tank full, I noticed the gas mileage was nowhere near what my previous FJ's had. I have been told that this has been an issue for many years prior to my purchase. I think that I found the culprit. A faulty choke cable. Over the 15 months of ownership, the choke cable has not given me any issues that would make me look at it. The bike sat idle for a few days. I went to ride it a few days ago and the choke hung up and would not return to the closed position, even with the choke knob pushed completely down. Verified that the cable was not broken and was finally able to get it functioning properly, but only intermittently. I then noticed that the choke rod on the carbs still had about a quarter of an inch to move before completely closed. I believe that this leaves the choke slightly on at all times and is causing the poor fuel mileage. This condition actually clears up a few strange things on the bike. I tried to adjust the idle awhile ago and had some really weird results. Took about 2 hours to get the proper idle set.

I put another choke cable on and verified the choke rod returns to the full closed position. Once warmed, the engine idle has now dropped 300 rpm.


Fred

[Troyskie]

Well found Fred .
You might want to balance the carbies and re do the mixtures now.

If you or the PO tuned the mixtures with the choke slightly on you might now be running too lean on the pilots.

Troyskie

[PaulG]

Just a thought...   I experienced a seized choke cable once. We were sitting in traffic going to the Port Dover Fri13th bike weekend. It was 10am and already 30degC. Took an hour to go the last couple of km as the police had all the roads blocked off.  (Had the pleasure of listening to monkey-barred-straight-piped-HD's revving to the red line while sitting there too. )

So to make a short story even longer...    By the time we parked I could smell burning rubber and saw wisps of smoke coming from underneath the gas tank.     My first dreadful thought was I warped the cam cover and had oil leaking. A cursory check showed to leaking. So we walked around for the day, but when I was leaving in the late afternoon I couldn't pull the choke out.  Had to get a pair of pliers to give it a good yank and it freed up and worked ok after that.

Next day I saw the choke casing (original +20yrs old) was worn through to the cable, and it had melted to the cam cover causing the seizure. Bought a new one soon after.

Possibly your PO may have had a similar issue causing a partial seizure. Or it  just got rusty inside 

Something for everyone to be aware of when your stuck with no way out of overheated stop-&-stop traffic.