Jetting my 78 GS1000

[80GS750]

shes alive!!!!!!

but not sounding healthy at all....

i can only get it to hold an idle for an extended period of time with the air screws 1/4 turn out....

i mean i seat them gently, then turn them 1/4 turn out... thats it.

whats the deal with that? thats where it idles the best... and its mostly running on 1-4, 2-3 are not doing much really...

im gonna mess with it some more and get some video for you so you can hear what she sounds like...

im getting some kind of low rattle in it.... at low rpm.. it seems to go away around 1500-2000

weird.... more to follow

oh and when i give it throttle, it dies.

 

[80GS750]

ok.... i got the highest idle thing with the air screws all the way in.... it runs the smoothest with them all the way down... i know thats not good


once it warms up a little bit, you can rev it a little, i only go to about 2500 rpm at most... and she comes right back down to idle, which is good...

but i noticed that when i pull the choke on, she revs way up!!!!

im running way lean!!! how do i correct this? different pilot jets???

 

[80GS750]

well i turned the fuel screws out 1/2 turn, then went to turn it over and my damn rotor bolt came loose again....

now im ****ed. time to quit for the night. this is like the 7th time is has given out on me!!!!

i torqued it down past the recommended setting last time too... it just keeps working its way loose... im gonna get some locktite tomorrow and that will solve my problem!!!

not the permanant stuff, just the regular kind

 

[80GS750]

ok well i have it running...

it sounds the best at around 2000 rpm

lower than that and she gets really clunky sounding...

i have to choke the crap out of it to start it up, and once it warms up a little bit it will idle for me just fine....

if i rev it up to around 3k or so she starts popping, like backfiring....

i have a leaky bowl gasket on #2 so im gonna pull the carbs and replace it, ill do a quick look too just to make sure my floats are set right and everything else looks ok.

it sounds like im lean? if i choke it when shes idling the rpm goes way up...

 

[80GS750]

i have the fuel screws at 1 3/4 out, and the air screws at 3/4 out....

 

[KEITH KRAUSE]

Red lock-tite should be used for the rotor (alternator). The shaft must be super clean and dried first.
Not sure what you've skipped or missed but something's wrong if the bike idles best with the side air screws only 1/4 turn out. Initially setting them to approx' 1 1/2 to 2 turns out is generally good enough for start up purposes. When fine tuned, they end up around 1 1/2 to 1 3/4 with your mods in most cases.
What are all the "basic maintenance" things you've done so far? These are things that should always be checked/done on any older bike, especially if you have no idea of it's maintenance history. Float levels as you mentioned are just one of many checks. You also say 2/3 cylinders aren't making much power? All those things would be taken care of or at least the problem determined with a basic check list. It takes time to fully check and tune a bike and if you're taking short cuts or assuming some things don't need checking, that's a good way to end up frustrated and spend even more time diagnosing/fixing things.
Any chance you have pilot fuel screws with broken tips still in the carb bodies? That would make it lean and cause problems as you say you have. If not, I think the carbs are dirty inside or?

 

[80GS750]

im starting to think i may have other issues also...

i put the bike back together... so i went over pretty much everything to make sure it was all either new or in tolerance...

i am thinking something may be clogged or not right in the carbs cause everything i have read shows that she should be running by now..

im gonna take the carbs off when i get back into town, tear them down again and check everything out for sure, again.

i will reassemble and put everything back to a starting base line and then report back...

we'll see what happens

oh i will be out of town for a week, so it will be a little while before i update

 

[80GS750]

well

SHE RUNS!!!!

you were right with the settings.... just about dead on. i had a bunch of stuff that must have come loose and clogged up my idle circuit... i took the bowls off and dipped them to get the gunk out, again... and now it runs.

i took her out on the road, and she accelerates good, but wont slow down at all...

i have to use the brakes to slow the engine down, any ideas?

im thinking mmaybe i need a stronger throttle return spring? maybe...

i dont know.

thanks keith

 

[KEITH KRAUSE]

It's easy to see if the slides are seating correctly and/or the throttle pulley is returning correctly. If so, I don't know what could be happening.

 

[80GS750]

i took a look at the spring and the way the slides seat and they look good... no issues there....


someone else said they had the same issue when the intake boots were old... so im gonna order some new ones and see if that fixes it...

mine are older and are kind of hard.. so its hard to say if they are leaking or not..

 

[KEITH KRAUSE]

Yup. Intake leaks will cause it too. But your description made it sound worse, like a sticking throttle or similar.
Hopefully just your manifold o-rings need replacing. Get the genuine Suzuki type, not some off-brand. They're cheap enough.

 

[80GS750]

i put new Orings in when i rebuilt the carbs.. got em from robert barr....

but the rest of it is pretty stiff.. im already ordered them.. Ill be sure to let you know if it fixes it for sure..

thanks again keith. your the man!!!

 

[80GS750]

ok....

i have new Orings, and new carb boots... so i dont think an air leak is my problem..

the rpm still hangs... when you rev it up.. the higher you rev it the longer it takes it to come back down.. i have not synched the carbs yet. could this be it? could it be the mechanical timing advance unit thing maybe hanging up or having some resistance in it and causing the problem???

she runs great at around 2 grand, if i take it down to 1500 she starts to want to die.... i need to get the carbs synched good and get it at a good idle and see if the hanging rpm problem still exists..

any ideas keith?

thanks again.

 

[TheCafeKid]

ok....

i have new Orings, and new carb boots... so i dont think an air leak is my problem..

the rpm still hangs... when you rev it up.. the higher you rev it the longer it takes it to come back down.. i have not synched the carbs yet. could this be it? could it be the mechanical timing advance unit thing maybe hanging up or having some resistance in it and causing the problem???

she runs great at around 2 grand, if i take it down to 1500 she starts to want to die.... i need to get the carbs synched good and get it at a good idle and see if the hanging rpm problem still exists..

any ideas keith?

thanks again.

I havent read ALL of this, but i saw you soaked the bowls. Did you soak all the jets and stuff when you cleaned the carbs too? If not its likely you still have some crap in your pilot circuit causing your hanging idle. If youve got no binding in the slides or stuck throttle, no air leaks in the boots (did you check the airbox boots too??) and your float levels are set right, and float valves are not sticking, and petcock is functioning, then Id go back to making sure the carbs are completely clean....completely...

 

[KEITH KRAUSE]

If there's no intake leaks, only ideas I'd have would be to check throttle cable routing and operation/play, checking slide operation when you bench synch, and checking the advancer. That's the only other things that could cause the problem.

 

[80GS750]

I pulled the carbs apart, and dipped all parts except the carb bodies themsleves.. and the floats. I pulled all the jets and screws and dipped them, and put in new 0 rings.

new intake boots. new pod filters. verified float heights.

throttle cable is working right. the slides all come back down quickly with a loud clack! when they seat.

ill have to pull my cover and see if my advancer plate is sticking up some how...

whats the best way to lube it? wd-40 or something?

thanks guys

 

[Guest]

I pulled the carbs apart, and dipped all parts except the carb bodies themsleves.. and the floats. I pulled all the jets and screws and dipped them, and put in new 0 rings.

new intake boots. new pod filters. verified float heights.

throttle cable is working right. the slides all come back down quickly with a loud clack! when they seat.

ill have to pull my cover and see if my advancer plate is sticking up some how...

whats the best way to lube it? wd-40 or something?

thanks guys

Why didn't you dip the carb bodies?

 

[80GS750]

when i tore them apart they really werent dirty inside...

and i noticed that the fuel T's that connect the carb bodies do not utilize 0 rings... so i didnt want to seperate them if i did not have to.

after blowing a ton of air through all the passages I know theres no way they are gummed up...

 

[80GS750]

KEITH!!!!!

she runs great!!! i got her synched up and she runs like no other... purrs nice and smooth for me. i put about 50 miles on it today and im very happy...

synching the carbs fixed the hanging idle problem..

i will do a dyna ignition sooner or later.. other than that shes done!

 

[KEITH KRAUSE]

Glad to hear it! She'll run even better if you do a proper synch with a vacuum tool. Enjoy the bike.