Carb syncing question

[mich1jon]

So far I've found all the answers to my maintenance questions by scouring the forum (a big thanks to you all), but I've finally reached an impasse.
With the help of the information supplied by David Raforth and his big brain, the carburetor rebuild went well and they're mounted up, ready to synch. Using a home-made water manometer, I've managed to get #1 and 2 synched with each other, and likewise 3 with 4, but when it came to getting the first two to match the last two, not happening. 3 and 4 are sucking harder than 1 and 2 regardless of any adjusting I do.
I'm assuming there's a vacuum leak somewhere, but I'm not seeing it. Any suggestions of where to look first would be appreciated.

Also, Dave refers to taking the idle mixture screws back to 2 1/2 turns, and adjust from there. Does this mean to totally back the screw out, and then turn it clockwise 2 1/2 turns?

Thanks all.

Oh, and pictures will be forthcoming, as soon as I figure out how to post them.

[Flynt]

Are you trying to do 2 at a time?  This is making the job tougher than it should be...  I use a set of 4 gauges that was pretty cheap and worked like a charm.  All 4 carbs right on the nose together with some averaging for throttle position...  you just can't effectively do that without having all 4 gauges (or manometers if that's your fancy) to look at while you're turning screws and twisting the throttle.  The reward you get in drivability is well worth the investment.

Side note: The gauges are not nearly as handy for the Keihins...  they have no on-the-fly adjustment, so you bench align them with a fixed spacing for the slides.  I'll try this and add using the gauges to guide my fine tuning of the slides.  Should be just about the right amount of head banging for my taste.

Frank

[fj11.5]

if its standard Fj carbs , wind in mixes till the just seat, then its undo 2.5 or whatever turns she likes

[yamaha fj rider]

A lot of here guys like 3 or 4 turns out. You have three screws, left side to sync 1-2, right side 3-4, once you have the right and left pairs synced then use the center screw to balance the two pairs. This can be done with only a gauge for two carbs. Doing all four at once the best answer. Hope this helps.

Kurt

[RichBaker]

The mixture screws are set by running them in 'til they just barely seat (don't keeping torqueing on them, it'll ruin the screws, the carbs, or both...), then turned out 'til they pass the "Blip Test". Could be 2 turns, 3 turns, whatever it takes...

[andyb]

Typically someplace between 1.5 and 4 turns is the usual range.  If you're not getting there and wanting more than four turns, try cleaning again (unless you ultrasonic'd or otherwise are really sure that things are spotless inside).  If you're wanting less, then check the size of the installed pilot and go down a size (from 40 to 37.5, etc), but that'd be unusual unless you went from pods to the airbox, or back to a factory-type exhaust.

[mich1jon]

Are you trying to do 2 at a time?  This is making the job tougher than it should be...  I use a set of 4 gauges that was pretty cheap and worked like a charm.

My home-brew manometer measures all 4 at the same time, but it can be a chore keeping the water from being sucked into the bike!
Think I'll get 4 of the gauges on Amazon for $19 each.

[mich1jon]

The mixture screws are set by running them in 'til they just barely seat (don't keeping torqueing on them, it'll ruin the screws, the carbs, or both...), then turned out 'til they pass the "Blip Test". Could be 2 turns, 3 turns, whatever it takes...

I'm the original owner of this '86 FJ, and as I delve deeper into the mechanics of it (the carburetor being the "Holy Grail" as it is the most intimidating to me!) I'm finding evidence of incompetent mechanicsmanship from the dealer I purchased it from, as I've suspected since day one. (lots of stripped screw heads, missing screws/bolts, etc.)
Two of the mixture screws are pretty boogered up from gorilla tactics and I'm afraid of tightening them til they barely seat. I haven't searched for replacement ones yet, but it looks like it's come to that.

[Flynt]

Think I'll get 4 of the gauges on Amazon for $19 each.

That's going to be ~$80...  for ~$100 I got a rack of four gauges, each with an in-line throttle valve (critical you have these to dampen the needle vibrations), all mounted on a nice hanger, with 4 lines and 4 each of 5 different fittings to connect with (none of which we need).  I also found this on ebay, but Randy has it now for $106...

http://www.rpmracingca.com/proddetail.asp?prod=Carb%3A4gage&cat=24

You'll use this thing a bunch, especially as you're getting the carbs dialed in.  Then I would synch anytime I was taking the tank off because it is so easy.  Good tools have a way of making some tricky jobs easy...  This is one of those times.

Frank

[yamaha fj rider]

Randy (rpm) has a kit for the carbs, I think it does all four. http://www.rpmracingca.com/proddetail.asp?prod=carbkit&cat=24d
Hope this helps?
If you need some help and are coming north let me know.

Kurt

[Dan Filetti]

Not to take food from Randy's mouth, but the Morgan Carbtune is also a really nice piece for about the same $$ as Randy's.  It uses stainless steel rods and works really well.  I have it and really like it.  I kno others do as well. Don't let the international shipping cost or times bother you.  I paid about $100 for it including shipping and it was delivered to my doors about 5 days after I ordered it.  Easy peasy. 

http://www.carbtune.com/

All that said, I really don't know much about Randy's in contrast, but knowing Randy from here to be a stand-up guy who understands quality, I have little doubt that his is also a good unit.

Dan

[oz.fj]

+1 on the Morgan
They're that good all your mates will want to borrow it
Now if I can just find mine..... 

[mich1jon]

Thanks for the options, but unfortunately I already ordered the ones from Amazon (they should be here tomorrow). I'm saving $3o, but the dampening feature Randy's has would've been nice to have. I'm quickly running out of riding season and really want to see the garage in my rear view mirrors. 

[SlowOldGuy]

Without some sort of damping valve or restriction, the gauges will be worthless.  They will flutter wildly and be totally unreadable and unuseable for synching.

DavidR.

[yamaha fj rider]

If you need some restriction you could make something. Let me know if I can help.

Kurt