Trying to Balance carbs, no vacuum at idle??

[wgranger69]

ok here is my story, i have a 1997 gsx600f ran a little rich but good and had great throttle response, i received the bike from my brother and he told me somebody put stage 2 jets in it but still ran fine, so i decided to clean the carbs ,check valve shims for clearance, and balance carbs , everything went great except now after putting it all back together it has really bad throttle response, wont idle smoothly keeps jumping up and down, so i adjusted the idle screw to keep it running to try to sync carbs and i get 0 vaccum showing on my morgan carbtune unless i rev it to 4000 rpm??ive checked for air leaks around the boots on both sides of the carbs and nothing,i have everthing on it even the air box, no hoses are off, so im lost now, i tried to balance them anyways even though i got no reading on my carb tune, so now im guseing all my balancing screws are way out of wack and i cant find where to initially set them, ive backed them all the way out and tried adjust like the hanes manual says but no luck unless im at 4000 rpm?? any help would be appreciated!!!

[92xjunker]

Did you plug the petcock vac hose on carb 4?

[wgranger69]

Yes have 2 other lines to tank plugged.

[TRPUT]

See if you can borrow another vacuum gauge - it might just be the Carbtune that is stuffed ... not an issue with the bike???

[maniac1886]

ok so here's my 2 cents.

A. There is no such thing as a stage 2 jetkit. Its stage 1 or stage 3. FYI. You're brother is confused or dont know what hes talking about.

B. When you cleaned the carbs, clearly you took the black caps off the top of the carbs. There are small o rings under those caps at the vacuum nipple. Did you see those and make sure they are seated correctly? First time i took mine apart, i overlooked those.

C. Bouncing idle is caused by a vacuum leak. In this case, probably a very large one.

D. You cant just not have vacuum, vacuum is created as the pistons move down in the cylinder. The only way you can have 0 vacuum is if the head was completely off.

E. You definitely threw your balance off. The best way to get them back close is to pull the carbs, back the idle adjustment screw back down to where it is just touching the throttle mechanism, and perform a bench sync. There are threads on here on how to do it so I wont waste my time explaining.

F. While you have them off, take the caps off, make sure your diaphragms are seated correctly as well as the vacuum nipple o ring. Reinstall them, make sure to cover the vacuum hose that comes out of carb #4 that would run to the back of the petcock. ( i use screws. Find one that wont slide in and out and thread it right into the open end of the hose, easy peasy, good seal be sure the one you use does not stretch the outside of the hose though, dont want to wop it out and lose precious vacuum once reassembled and warm.)

G. Suck on the hose of your carb tune, you should get some type of response. If not, its probably hosed (no pun intended) at that point, well, the solution is obvious.

F. After that, try to sync them again. At this point I cant think of anything else that could be wrong while still allowing the bike to run. Even if it is only at 4K.

[wgranger69]

maniac1886,trput,92xjunker,-thanks for the help guys , appreciated, great info i will defiantly recheck the small o rings at the vacuum ports on the black tops, i bench synced the carbs using a drill bit and it seem very close, i also took the caps off the A/F mix screws and set all screws to 2 1/2 turns out, started the bike and took right off, but when i took the choke off it wanted to die so i tried to put my hand over the inlet to the breather box and it ran great so i defiantly have a vacuum leak some place, guess its time to pull the box and check for cracks. Checked the Carbtune with two of my other bikes and works great so i know that's not the problem. As for the jets that my brother said were installed ,i took this photo of them when i had them out looks like it said P285 ?? i have a photo on my laptop of it but dont know how to post onto here.

[skjeflo]

maniac1886,trput,92xjunker,-thanks for the help guys , appreciated, great info i will defiantly recheck the small o rings at the vacuum ports on the black tops, i bench synced the carbs using a drill bit and it seem very close, i also took the caps off the A/F mix screws and set all screws to 2 1/2 turns out, started the bike and took right off, but when i took the choke off it wanted to die so i tried to put my hand over the inlet to the breather box and it ran great so i defiantly have a vacuum leak some place, guess its time to pull the box and check for cracks. Checked the Carbtune with two of my other bikes and works great so i know that's not the problem. As for the jets that my brother said were installed ,i took this photo of them when i had them out looks like it said P285 ?? i have a photo on my laptop of it but dont know how to post onto here.

If you did your bench sync using a drill bit as a spacer the your throttle plates are WAY too far open as a baseline.

From Carbs 101:

"Reinstall the idle adjuster cable until it just barely touches the starter tab of the carbs. Now look into the engine side of the carbs at the butterfly valves. (There are three small holes – familiarize yourself with them.) Look at carb # 3 and adjust the idle cable until the first small hole (towards the outside of the carbs) on the bottom of the carbs is HALF VISIBLE. Then adjust carb # 4 using its idle adjustment screw, (located from the top between the carbs – it’s on the arm that moves when you twist the throttle). Take this carb to the same point by only adjusting the screw. DO NOT adjust the cable any more – it is only for carb # 3 at this point. Next, adjust carb # 1 to WHATEVER carb # 2 is, so they are equal. Then, adjust carb # 2 to the same point as 3 & 4 (first hole half open). Once all four carbs are equal and at the same point, (HALF the first small hole showing open) you have visually synchronized your carbs! You are now ready to reinstall them in the bike and synchronize them exactly."

[wgranger69]

Skjeflo bro i cant thank you enough !!! the info you gave me worked like a charm!!! WOW yes im totally impressed every detail was EXACT and my baby is back in action!!
Thanks a million !!