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78 GS750E carb/vacume help PLEASE

  • Thread starter Thread starter Yura
  • Start date Start date
Y

Yura

Guest
Here is what im confused about...
on the fuel petcock there is a smaller line that is disconnected on my... where dos that go?
also, on the carbs, there is 3 nipples and one of them is puling some major vacuum (they are all in line pointing at the seat/gas tank area, they are at a 45 digry engle) what are those and where do they hook up to?
these are MIC carsb. im trying to adjust the carbs and its not making any sense to me, my manual dosnt have a diagram and the guy that had this bike before me is clueless...
PLEASE HELP!
thank you
 
The vacuum line on the petcock goes to a nipple on the number 2 (I think) carb to supply vacuum to the petcock. When vacuum is present, the petcock should flow fuel.
The 45 degree nipples are closer to the head, on the intake boots. They are for hooking up a manometer to sync the carbs and they should be plugged when not being used for syncing.
What kind of bike is it?
 
sorry, i know the ones for the manomiter, thats not the ones im trying to discribe... (those are pluged)
there are niples of the carbs that are siting at an angle (3 of them) one of them is puling vacume, the ather two dont aper to do anything...
i conected the one to the fuel petcock, it smoothed out alot, but i dont know what to do with the other two... are they just breathers of some sort?
also is a jet on the botom of the carbs where the bowl sits... what are those fore? (somone messed with my carbs and now i cant get it adjusted corectly)
when i iply the throtle rapidly it seams to get too much fuel and just dies...
 
At least give correct info !! He has slide carbs the petcock vacuum line hooks to the #3 carb !!!!! 4 hoses on float bowls drain to rear- no connection. fitting without vacuum on carb #2 & 4 are just vents no hookup either, route up and over the airbox
 
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sorry if i didn't give correct info, im not to knowledgeable about these bikes...
all i know is that they are mikunis and they are not the vacuum type carbs.
i still need to know what the bottom adjustment screw/jet is responsible for. its right next to the bowl on the bottom of the carb...

p.s. im downloading the manual for mikuni carbs as we speak
 
SqDancerLynn1 said:
At least give correct info !! He has slide carbs the petcock vacuum line hooks to the #3 carb !!!!! 4 hoses on float bowls drain to rear- no connection. fitting without vacuum on carb #2 & 4 are just vents no hookup either, route up and over the airbox
Click to expand...
Well, I tried, on mine it hooks to #2. I dont know about VM carbs.
 
the line between 1-2 and 3-4 is just a breather lines, the one on the left hands side of #3 carb is vacuum for petcock, thank you
now the question is... what the heck is that screw that in every manual i look in, says do not touch.... its located on the bottom of the carb tords the motor next to the bowl... :confused::confused::confused:
 
I should take a picture, but is it the cam chain tensioner. At the same site referenced in my post is a cam chain tensioner rebuild paper, With PICTURES!

See if that is what you're describing.
 
nope, this is on the bottom of the carb, not on the back side of the head :(
 
On the bottom of the carb/float bowl is the fuel screw that is recessed up into the float bowl. There is one for each carb, flat blade screw.
 
this one is adjustable from the outside...
i played with them... got them to where its running nice... those screws are HI rpm fuel mixture... that was a pain in the (_!_) but i think i got it good inouf for now, till i get the sincro tool and coned filters.... and ill have to readjust them again... :cool:
 
The fuel screw on the bottom of the carb 5/8- 3/4 turned out from lightly seated. The side air screw about two turns out

coned filters ?? If you mean pods ? You will need to rejet the carb
 
I'm at 5500 feet in Albuquerque,NM so my settings are a bit different then most ppl :(
do you think ill have to go to a smaller jet size when i change to pods?
 
ok, now till about 3500 rpm has intendancy to bog down... idles really smooth...
any sudjestions?

p.s. how many jet sizes down do i need when i change to pods?
 
Yura said:
... on the carbs, there is 3 nipples and one of them is puling some major vacuum (they are all in line pointing at the seat/gas tank area, they are at a 45 digry engle) what are those and where do they hook up to?
Click to expand...
Other details later, but the one on #2 is a vent for 1&2, the one on #4 is a vent for 3&4. The one on #3 is the vacuum line that should be connected to your petcock.


gearhead13 said:
The vacuum line on the petcock goes to a nipple on the number 2 (I think) carb to supply vacuum to the petcock.
Click to expand...
This is true on CV carbs from '80-on, but earlier VM carbs have the vacuum nipple on #3.


gearhead13 said:
Well, I tried, on mine it hooks to #2. I dont know about VM carbs.
Click to expand...
(see comment above)


Yura said:
the line between 1-2 and 3-4 is just a breather lines, the one on the left hands side of #3 carb is vacuum for petcock, thank you
now the question is... what the heck is that screw that in every manual i look in, says do not touch.... its located on the bottom of the carb tords the motor next to the bowl...
Click to expand...
That is your pilot fuel screw. (details later)


Riding Again said:
I should take a picture, but is it the cam chain tensioner.
Click to expand...
No, he is talking about a screw on the carbs, not the cylinder block.


Yura said:
this one is adjustable from the outside...
i played with them... got them to where its running nice... those screws are HI rpm fuel mixture... that was a pain in the (_!_) but i think i got it good inouf for now, till i get the sincro tool and coned filters.... and ill have to readjust them again...
Click to expand...
Those are NOT the HI rpm fuel mixture. They are the IDLE mixture screws. As SqDancerLynn mentioned, they are adjusted about 5/8 to 3/4 turn out (at your elevation, maybe as little as 1/2) and the air screws on the sides of the carbs adjusted to 1 1/2 to 2 turns (maybe a little less at your altitude).



Yura said:
I'm at 5500 feet in Albuquerque,NM so my settings are a bit different then most ppl
do you think ill have to go to a smaller jet size when i change to pods?
Click to expand...
NO. You will not go to smaller jets when you go to pods, you will go to LARGER jets. Albuquerque is, indeed, over 5000 feet, as is most of the area around you. If you don't ever go anywhere near sea level, you might get away with stock jetting because the altitude will richen the mixture a bit, but maybe not enough.


Yura said:
p.s. how many jet sizes down do i need when i change to pods?
Click to expand...
As mentioned above, you will not jet DOWN, you will jet UP. How many sizes? That depends on how well the pods and pipe breathe. This is checked by doing plug chops. The procedure is outlined on BassCliff's website.

.
 
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