New to this board, new to this bike. Recently purchased a 81 GS450T. Had been in storage. Put in new plugs, new air filter, clean fuel, and removed and cleaned the carbs. Bike runs fine, starts with no problem. The problem I have is at idle. If I set it at 1200 rpm and then rev it, it jumps to 3000-4000 rpm and stays there. If I set the idle down a little and rev it , the rpm's drop but then the bike stalls. I can't get it to have a stable idle. Any suggestions?

Thanks,

If you haven't had the chance, it sounds like your coils are failing.  Change those out and tell me how it worked out for you.  My girlfriend is having the same problem right now, and I'm going to the suzuki dealership this afternoon to get a new coil.  Also, how old is the gas in your tank?  that can create a big problem, as gas loses potency over time.  Most stalling issues are created by a problem with the motor getting spark.  Just remember that simple rule, and 9 times out of 10, you'll know the easy fix.  Hope this helps!

sounds like you have some sticky issues, either the cable isn't releasing all the way (lube cabe to find out) or the slides could be sticking.  either way easy fixes.  just start with the cable, and work your way back to the carbs.  worst case senerio is that you are having a jetting issue with your idle circut and need to re jet the bike.  but more than likely the carbs are just dirty and somethig is worn and not closing all the way.

The gas is fresh gas. Will check the coils out.

Thanks,

I would check the throttle cable to ensure there is free play.  Then I would check for air leaks around the carb boots.  It's possible there's still some blockage in your idle circuit; it is difficult to clean-out thoroughly.  This problem can probably be solved by giving the EPA pilot air screws a turn "out" from the factory setting.  On the GS450 the screws are accessible from the side toward the front of the carbs just above the bore.  To access the screw, which is blocked  to prevent tampering, the filler will have to be lightly drilled out until a brass plug is penetrated.  This is the carb tuning that really matters.

ok, coils wouldnt be even close  if it only dies  when you turn the idle screw down.   turing down the idle screw and it droping away tells me its not MUCH of a sticking problem but more of a Vacume leak issue,  the boots, the Orings behind the boots, ORings inside the carbs etc

Yea exactly what bluknyt said ... coils ... gimme a break ... the damn coils will cost you more than the whole damn bike is worth ... so in any case replacing them is stoopid ... carbs ... cable, air filter, air box, choke and manifolds are the usual suspects air comming in from somewhere or gas not comming in like it should ...
Cool.
Srinath.

yeah, my carberation Knowledge is growing, not only with Mikuni but with Kiehin as well.  (Standing ontop of a milk crate shaking fist to the sky) SOON i shall be the carburation King.  (then points a tattered slide diaphram at srinath) thats right, im gunning for your slot of guruism.  

BTW, KZ440 really woke up with 110 mains K&N filter and stock exhaust. snatched the front wheel off the ground from a stop sign

Quote from: Blueknytyeah, my carberation Knowledge is growing, not only with Mikuni but with Kiehin as well.  (Standing ontop of a milk crate shaking fist to the sky) SOON i shall be the carburation King.  (then points a tattered slide diaphram at srinath) thats right, im gunning for your slot of guruism.  

BTW, KZ440 really woke up with 110 mains K&N filter and stock exhaust. snatched the front wheel off the ground from a stop sign

Whaaaaat ... OK I need that formula ... the KZ has been laughing at me for 5 years ... of late its crapping out too much to even laugh ... 110 mains huh ... I'll try that ... so you got stock LTD carbs and 110's ... what is mix screws ... and what else it got ... See you already guru ... OK You can be emperor ... or president ... or El Presidente what ever americans are ... guru is overly injun ... BTW ... I should've take you up on the seca carbs offer a few months ago ... those are a piece of cake ... easy money ...
Cool.
Srinath.
:lol:

my 440 had 88 mains stock, bumped to 102 the first time and found some nice power hiding, faster warm up less choke for startup. and nicer idle. figure the 110 would be about perfect, but its stock exhaust. the stock pilot idled ok and didnt hicup off idle once warmed up so left it stock, you could probly bump it 2 points if you wanted to, but i left mine alone

ok, some wisdom ive learned from the 2 stroke and thumper forums, 2 strokes are really picky on thier screw adjustments right down to the 1/16th of a turn, 4 strokes/thumpers arent

counting turns in is just to help you put it back in the ballpark when you pull the screw out to clean and blow air through it.  the mixture screws will cover from full volume of the pilot jet to about 2 sizes down on most bike carbs

meaning stock 37.5 the screw will handle the flow of 37.5 down to a 35.5 Volumetricly speaking

so when you go to a 40 pilot, the scew will cover from full open 40 and close down to about 38, acording to a few patches of carb tinkering ive read over.

diff altitudes need diff adjustments, idle circut isnt as tempermental as the mains

bottom line, the turns out isnt a specific carved in stone number everywhere.  

the idea is, once rejeted and you get it idleing about normalish, pick one side, and start by turning the screws in slowly, you should hear the idle comeing down, now start turning it out slow, you will hear the rpms come up when they reach a high point and dont change anymore, stop,  go to the other side and repeat, turning in, engine slows abit, start turning out, when it reaches a peak stop.  reset the idle stop screw to desired rpm.

now do it again, shouldnt take as much overall adjustment, but now, just as peak idleing rpm is reached  back it up about 1/4 turn and do the other side, reset idle speed again if need be. now you can kill the engine and count the turns in for future referance with that pilot jet setup. ive done this with both the 440ltd and the GS500 and seems to be working nicely on both accounts.  MUST NOT BE ANY VACUME LEAKS  or the above tuneing will not work

OK 88 to 110 on a stock bike (OK with airbox K&N) ... I think I better start putting in any jets I got laying about ... its bad on mine ... just like you'd expect with 5 sizes off mains ... how did theyt let it out the factory like that ... :x
Cool.
Srinath.