Vacuum Line

[Ront]

Hello   I trailered home a 1986 FJ1200 today with 27000 miles.   Bike seemed to run well but when I parked it in my garage it starting leaking fuel.  That didn't surprise me on an old bike-petcock not closing, floats maybe sticking, fuel inlets leaking etc.  So I removed the tank getting ready to pull the carbs--I know there should be a vacuum line running to the petcock-but I was surprised to see a vacuum line running from the petcock to the IC ignitor---does anyone know why?  Thanks

[movenon]

Welcome ! I have a 1990 so mine is a little different. Someone will come on shortly with better information. I am thinking that that line should run from a vacuum port at the #2 carb and go's to the TCI / Ignitor box to adjust the electronic advance of the ignition circuit. I think there is another vacuum line going from the engine to the petcock. I am on thin ice here but it's a start !
Hang in there, help will be here soon . 
Leaking fuel is a fairly common problem with all carbed bikes. But it is easy to fix. Sounds like you are acquainted with the issue. 

George

[Pat Conlon]

The vacuum line connected from your #2 intake manifold to the ignition box is part of the emissions system.
How it works is, when the throttle plates close on your carbs, the vacuum goes up and signals your TCI to advance the timing, flashing off any unburnt fuel....also helps keep your plugs clean.
Under normal condition (throttle plates open with a low vacuum signal) the ignition timing is hard programmed into the TCI and advances based on engine rpm.

[Ront]

Thanks for the responses - my petcock passes fuel with no vacuum - that doesn't surprise me - but someone attached a vacuum line from carb 1 to 2  and a line from the petcock to the ignitor-obviously not correct

[Pat Conlon]

Ok, you know about the petcock...buy a new one.
On the vacuum line to the TCI, check to make sure the diaphragm internal to the ignition box is not ruptured.
Hook up a piece of tubing to the vacuum port on the ignition box and suck on it...you should not be able to draw any air thru the tubing....if you can it means that the diaphragm is torn leaking air. If that is the case, do not hook up that vacuum line to your #2 cylinder, it WILL cause #2 to run lean.
Simply plug off the #2 vacuum port, the bike will run fine without the advance.
(That might be the reason why it is disconnected to begin with)
On the early FJ's the only way to fix a leaking diaphragm is to replace the entire ignition box (stupid)
On the late model FJ's the vacuum advance module is separate from the ignition box (smart)

Our FJ's run just fine without the advance....again, the only time the ignition is advanced is when the throttle plates are closed....

[Ront]

Thanks for the reply   I'm looking forward to getting this bike running right and riding it this spring-My brother had a new one in '86 and I loved it-I paid $1400 for it and it seems to be in pretty good shape with all the usual problems of an older bike. Thanks again-I'm sure I'll have a lot more questions in the future

[Pat Conlon]

Glad to help. When you get a minute head over to the introductions section, say hello and tell us a bit about your self...should we call you Ron?

Welcome to our camp fire.....

[movenon]

Thanks for the reply   I'm looking forward to getting this bike running right and riding it this spring-My brother had a new one in '86 and I loved it-I paid $1400 for it and it seems to be in pretty good shape with all the usual problems of an older bike. Thanks again-I'm sure I'll have a lot more questions in the future

Like Pat said head over and introduce yourself.  If you can let us know where you are located.  This is a great group of FJ owners located all over the world. This year is the 30th anniversary of the FJ. Check out the files section and think about attending one of the rallies this year.  Nice thing about these bikes is all the expertise from the members here, some have owned there's since new.  Lots of parts are still available and for starting point check out Randy's site at
http://www.rpmracingca.com/products.asp?cat=39  Randy is a member here and very highly recommended.
Also http://www.boats.net/parts/search/Yamaha/Motorcycle/parts.html and http://www.2wheelpros.com/oem-parts/yamaha-parts.html
George