How closed is closed?

Right now I am in the middle of trying to get my carbs right.

Among all the things done I have replaced all the throttle shaft seals. To do this I had to take the butterfly valves off.
Now heres the problem. my bike revs up real badly and stays there. Sometimes (now that the main idle screw is all the way out) it revs down but very sowly.


Problem:
If looking at my butterfly valve there are two holes visible when it is as closed as I can get it.
The idle mix screw and the first of the following two holes on the same 'circuit'.

I hope I have been specific enough and my question is how closed are your butterfly valves? is the only hole visible the one for the adjustable idle?


My bike is a 1981 xj 650


Thanks!



//Ivar

 

Are the same number of holes visable in all four carbs? the number three butterfly should pretty well cover 'em up (as I recall) if the idle set is backed all the way out.

even with the idle adjuster backed all the way out if any of the sync adjusters are wrong then those other carbs could be set on too high a throttle position to idle.

Think of the sync screws as idle sets for the number 4 and 2 carbs that are based on the number 3 (where the main adjust operates) and the number 1 adjuster is the same but based on the number 2. You need to bench sync as part of the reassembly procedure. many people have various techniques for bench syncing. Here is mine.

loosen all the bolts on the "racks" or "rails"... the cross pieces that hold the four carbs together. Be sure there are no burrs or nicks on the intake sides of the carb throats and lay those on a piece of glass or if you're lucky a machinists granite slab. something dead flat.
Let them all settle so they're totally coplaner and snug the screws, now tighten the screws, now check to be sure they're still all flat and tighten a bit more and check again.
OK they're together properly. Now lay them on the table with the butterflies pointing up toward you and put one BB in each. Slowly and carefully open the throttle until a BB falls through. If it was NOT #3 first then you need to back off on the adjacent sync screws. If #3 fell first then the #2 and #4 need to open a bit sooner. Don't worry about #1 until AFTER doing #2.
Get it so no matter how slow and careful you open the throttle you can't tell which falls first. Also take care that after one has dropped don't close the throttle again without first dropping the rest. closing the butterfly ON the BB can mar things that ought not be. Also when making adjustments to the sync screw always finish by tightening to take any minute amount of lash out of the screw (yes there are springs but still). What I mean is that if you intend to tighten a quarter turn, ok fine, clockwise a quarter turn. If you intend to LOOSEN a quarter turn then turn counter clockwise HALF a turn then clockwise a quarter turn.

I hope this all makes sense.

 

You should have BENCH Synced the Butterflies with a THIN Feeler Gauge.

A quarter-inch wide strip of 3X5 Card is good.
Resume' Paper
Business Card ...

The IDEA is to Mechanically Synchronize the Throttles so that when you are done, ... they will CLOSE.

Allowing you to SET the IDLE with the Engine solely dependent on the Pilot Mixture Screws for Idle.

If the Throttles are "Hanging-up, ...

Triangulate Resume Paper at 12, 4, & 8 O'clock to CENTER the Butterfly while you tighten the Butterfly Plate to the Throttle Pivot Rod.

 

Thanks for the tip Rick and buddha

I believe that might be the problem, that the butterfly plates are incorrectly aligned. I will try to reposition them tonight...

I did not get an answer to the question though...
Rick: Are there more holes than the idle mix hole when your butterfly valves are al closed?


Thanks for the fast replies!
My bike is really giving me a hard time. Took it to a friend who is a certified mechanic and has been working with fighter jets, race cars and vintage cars. He recommended me I tried to get a hold of another set of carbs! I just want a rideable bike for the summer! =)