carbs

[tc862011]

so i have got the bike running even better, but i have the fuel screws out 3 turns and the air screws out 2 and i can get up to a good speed, but there is still snapping and popping and when i wot it theres nothing there, i have the stock airbox the stock size jets all the way around, new intake boots, new exhaust gaskets, so its not a leaky vaccum issue, does that sound right to have the fuel screw put three turns and it still act lean

[rustybronco]

The fuel and air mixture screws only have an affect from idle on through about 1/4 throttle opening.

[tc862011]

so what would it be

[Nessism]

What maintenance have you done on the bike? Please read the Newbie Mistake thread linked in my signature and let us know if anything rings a bell.

[tc862011]

it runs fine up to 1/4 throttle then it starts the popping and snapping, i need some guidance on what it would be please

[tc862011]

i have rebuilt everything, frame up almost everything is new or as new as it can befor being almsot 40 years old its just the adjustments at this point

[MisterCinders]

If your idle is good with those settings, you have a fat air leak somewhere. Fuel screws are usually half the turns of the air screws.

Otherwise, poor running at 1/4 throttle until about 3/4 throttle means the needle needs to move.

[Nessism]

Set the fuel screws to 7/8 of one turn open, and the air screw at 1.5 turns. The bike will run decently at those settings if the bike is properly maintained like you state. Fine tune the screw from there after you perform a vacuum sync job. The final screw settings should be within about 1/4 turn of your starting point.

[MisterCinders]

Also, what bike? What exhaust?

Check the link in my sig about running badly.

[tc862011]

ok and whats a good way to sync them, i have the tool but it looks like you need to take the gas tank off to adjust the slides, how do you keep the bike running to do so, and why would the needle have to go up when everything is stock. and i dont see how i would have an air leak somewhere

[tc862011]

1978 suzuki gs550, stock air box and stock exhaust

[tc862011]

o an how do you adjust the fuel screws with out taking the carbs off, i have tried everything and i cant get anything in there with any type of accuracy

[Nessism]

o an how do you adjust the fuel screws with out taking the carbs off, i have tried everything and i cant get anything in there with any type of accuracy

You can try a screwdriver bit, but taking the carbs off might be easier.

[tc862011]

yea the easiest but more lengthy part is taking them off, just trying to get out dropping the airbox to take the carbs but o well

[BassCliff]

Hi,

I have a very simple auxiliary tank for when I'm doing carb tuning/sync'ing.










Thank you for your indulgence,

BassCliff