Synching woes

[Meltdown480]

I return with more issues. Threw newly cleaned bench synched carbs on bike. Starts nice but has a little pop in the exhaust. Generally idles around 1k but any messing with the screw doesn't seem to do much. Will occasionally jump up to around 4k. I have it running on a iv bottle but with only occasionally open the valve to add fuel. I hooked up a vacuum gauge and i got the pressures to read around 25,15,25,25 . I know basically nothing so I was thinking about just giving it to a mechanic. Any help would be appreciated.

[fj1289]

Here is a link to the carb files

https://fjowners.com/index.php?board=21.0

And here is a post from there specifically

https://fjowners.com/index.php?topic=11258.0
***IMPORTANT NOTE*** Normally I would caution against opening any links posted by Klavdy - some things just can't be unseen!  But this one is safe!

And, another link from Klavdy's link

https://www.angelfire.com/ia/z/FZ1carbsync.htm

Both of these post are specific to the Yamaha FJ1, but it all applies to our FJ carbs. 

Go thru these and give it a shot - then come back with your success story or more questions!

[Meltdown480]

Here is a link to the carb files

https://fjowners.com/index.php?board=21.0

And here is a post from there specifically

https://fjowners.com/index.php?topic=11258.0
***IMPORTANT NOTE*** Normally I would caution against opening any links posted by Klavdy - some things just can't be unseen!  But this one is safe!

And, another link from Klavdy's link

https://www.angelfire.com/ia/z/FZ1carbsync.htm

Both of these post are specific to the Yamaha FJ1, but it all applies to our FJ carbs. 

Go thru these and give it a shot - then come back with your success story or more questions!

I got the gist of synching in general but I think I have more problems to address before hand. Reading the links however made me realize I probably didnt have the gauges probably positioned

[fj1289]

From your first results, you are pretty close.  You want to adjust the synch screw between #1 and #2 to get them equal (or close to it).  Then adjust the synch screw between 3 and 4 to get them equal (which they are).  Finally you adjust the center synch screw to get the left pair to match the right pair. 

The synch screws adjust the butterflies so they are all equal.  The idle speed knob is then used to adjust the idle speed. 

All this is separate from the idle mixture adjustments - which is another discussion. 

A lot of "mechanics" won't touch a carbureted engine any more.  These things are basic enough that with a shop manual, patience, and some help from here you can learn to do most everything your bike will need! 

Also from first post - just turn on the fuel valve from your hanging tank - you want the float bowls full - not some part way always changing level that will mess with your results.