Ok so I've had the bike running for a while now but the idle under 3k sucks.

K&N lunchbox, stock exhaust.

-float height is deal on the gasket level. As in... the bottom of the minuscus (i think thats right.. been a while since i was in chem)

-#40s are in

-#147.5 for mains (everything runs great above 3k)

-2/3/4/5 turns on the mixture screw no real difference. I can get it to go with lots of turns when its just sitting there but when i ride it it does the same thing.

- I've used both 1 and 2 shims, no difference

-no throttle binding

-tank/carbs all clean as a whistle, no debis floating around to clog anything.




Ok with that said... the previous owner had the choke cable really full of slack. So I tightened it a bit and the choke will open and close completely. When I turn the choke 99% closed it will rev and stay at 3k but with it closed 100%, just that extra bit the bike will just die. The idle can be maintained with the cable closed 100% with a lil throttle but it needs constant bliping.

are the pilots essentially the only thing in question? Should I try 42.5's -NB? I can always get some 40bleeders from a local shop with no waiting. that would definitely end any doubts of it being lean down low right? I really hope I get some constructive answers. HELP! 

What about your idle adjustment screw?  If it's backed too far off the throttle will completely close and the bike will die unless the choke is on to provide air/fuel.  Since you mentioned that it runs allright if you blip the throttle maybe you just need to turn the screw in a bit?

-M

nope, it is turned pretty good. definitely making contact with the throttle wheel.

If i keep turning it it will really run away up to 4 or 5k.

There have to be 30 threads with this near same problem... seems like no one ever posts up when they fix it. This is really making me want to upgrade bikes sooner than later. 

i think you have the Idle air control screws mixed up with the idle speed screw

did you remove the carbs turn them over and remove 2 little brass plugs using a drill and a machine screw to access the IAC screws?

Quote from: werase643 on July 06, 2006, 09:33:50 PM
i think you have the Idle air control screws mixed up with the idle speed screw

did you remove the carbs turn them over and remove 2 little brass plugs using a drill and a machine screw to access the IAC screws?

no mix up. Caps are gone and "idle air control screws" or as i refered to them "mixture screws" are 3 turns out.

I'm looking for a suggestion on my next course of action. If I increase the float level will that effectively make my bike more rich on idle/throughout the powerband? Does it even sound as if I am lean under 3000?

Quote from: CRXDrew on July 06, 2006, 09:41:15 PM

Quote from: werase643 on July 06, 2006, 09:33:50 PM
Does it even sound as if I am lean under 3000?

Does the bike hang around 3k when its revved. if so your lean. BTW How do you increase the float level.

new plugs
start bike and let it idle for a while
turn off bike
pull a plug.....
what color is the plug?

i doubt it is lean with 40's


actually i think they are air mixture screw actually

it has been so long... i thought i set them at 2.5 turns out

Quote from: dwn4whadever on July 06, 2006, 09:44:43 PM

Does the bike hang around 3k when its revved. if so your lean. BTW How do you increase the float level.

yea it'll hang around 3k or a bit more. After doing the u-tube method I would bend the metal tab down (in relation to the bike with the carbs still attached) and then more fuel would be allowed into the bowls.

Quote from: werase643 on July 06, 2006, 09:46:37 PM
new plugs
start bike and let it idle for a while
turn off bike
pull a plug.....
what color is the plug?

i doubt it is lean with 40's


actually i think they are air mixture screw actually

Mixture screws can be 5 or 6 turns out... it just makes the whole thing pig rich... maybe i need 42.5 pilots... but that sounds really rich... atleast from what i've read.

BTW I can barely get the bike to idle long enough to get a good "sample". This was one of the first methods I tried, i've been using it on the cars I've turbo'd for years. But yea... if i could get it to idle this would be easier. I can get the bike to sit at 3k and get it to run rich with 5 turns, good at 3 and lean as hell on 2.

My question now is, if i were to increase the float level if it would effectively richen everything. I remember serintha (whoops spelling) saying something to that effect. I really hope he chimes in here.

if it idles good at 3 turns....why do you want to adjust the float level?

You shouldn't have to change the float height.  If it's even with the gaskets then it's perfect, don't touch it.  Do you have a good seal between the carbs and the intake boots?  Are the clamps securely tightened?  Are you positive there is enough slack in the throttle cable?  I had the same problem and my fix was to loosen the cable up. 

as per suz tech man
it is the idle screw.....preset at factory
as the air comes into the idle air jet
it mixes with the fuel being sucked up by venturi effect thru the pilot jet
andthe air/fuel is metered into the intake port by the pilot screw
also a little is blead into the intake tract through the bypass ports(little hole below the butterfly valve)

if ya raise the fuel level the "pressure" from the fuel height will cause more fuel to mix with the incoming air
thus enrichening the ckt

but i don't think you are lean

147 jets? that strikes me as slightly huge.

I thought 147's were for use with Intake AND exhaust.

yeah, i thought that also....but it runs good up top

do a plug chop up top....and i bet a beer it's rich there also

This comes up every once in a while, when I put 40 pilots in my bike, it ran like a bag of shaZam!, way to rich. So it could be that, but everyone else seems to run fine on them.

Quote from: Mandres on July 06, 2006, 10:12:27 PM
Do you have a good seal between the carbs and the intake boots?  Are the clamps securely tightened?

+1 revs not dropping could be a sign of being lean, or air entering post-carbs.  Try spraying some WD-40, starter fluid, propane, or other flamable gas/aerosol on the intake boots and see if the revs change.

+1 on also checking your plugs and see what they tell you, if it is rich, drop the pilots a size and leave those floats alone

i actually never changed the pilots....left them stock

played with the pilot screws and needle position only

did a good warm up with the choke while i put on helmut and gloves
then rode
pulled hard and clean

What kind of pilot jets did you put in?  Were they Mikuni  N151.067-40 non-bleeding jets, or did you end up with bleeding jets? 

ok... sorry about the late response

-40 non-bleed's for pilots that exact part number ordered from bikebandit.com

-definitely sealed in the intake boots. I actually took them off the bike at one point and made sure that even the connection between the head/boot was sealed (put bit of RTV just incase).

-lots o slack on the throttle cable. Adjuster has been set as far as "maximum slack"

-it runs a bit rich up top yes, this is confirmed with plugs. But the thing is its rich only when idle ... but not boggy/slow/bad. I prefer a bit more rich/cooler than running it on the leaner/hotter side.

Ok so now I'm gonna drop down to 145's to lean up the top a bit. But this leaves me stuck still with the down low problem. I might try to go back to the 37.5's maybe that'll help. Has anyone ever heard of them needed 42.5 pilots? Also I'm gonna mess with the choke some more... I have no reference point really on inspecting a choke (coming from my perspective working on lots of FI cars) so I figure if I was to glaze over anything it would be that.

I'm gonna also go and check valve clearances in the morning. werase643 was talking about he venturi effect pulling fuel through the pilots.... maybe the vac is weak because of overly.... tight(?) valves? Its been so long since i've encountered tight valves on a vehicle that I forget all of their side effects.

wish me luck. I swear to everyoneo on this board... i will make the most killer FAQ out of the infamous gs500 idle hang if I can actually get this damn tihng fixed.

checked the valves and both exhaust valves were tight.

R side 2.55 (couldn't get the .038 in there)

L side 2.60 (.038 also didn't go)


I'm off to a local shop now to grab a 2.50 and put the .55 where the .60 was. Can anyone confirm if tight valves can contribute to a sucky idle?