Am I on the right track??

[Anonymous]

I am fine tuning the bike (1978 gs 750E) this winter for hopefully alot of miles next season. Rebuilt the whole front end of the bike (bearings, forks, brakes). Put new suspension on the rear. Now I am fine tuning the carbs. I havent been able to get the carbs right yet. I have two burning about right (1,2) and two burning very rich(3,4). Does this sound right?? Back out air/idle misture screws to achieve maximum idle, 1 1/2 turns out on the adjustable jet on bottom of carb. Set float heights. Does that sound about right? How will the jet on the bottom of the carb effect the way the plugs burn??

[earlfor]

Re: Am I on the right track??

JoCo, on my 79 750E, the idle air screw is set to 2 turns out.
The adjustbale fuel needle/jet on the bottom of the carb is set to
1 1/4 turns out. The float heights are set to 25mm. I'm pulling about 25 inches of vacum at 2300 to 2500 rpm on cylinders 1 and 4 and about 23 inches of vacum on 2 and 3 at that rpm. All four plugs are buring a medium tan. Stock air filter and airbox and stock exhaust system. Timing is set on the marks..stock.

Earl

I am fine tuning the bike (1978 gs 750E) this winter for hopefully alot of miles next season. Rebuilt the whole front end of the bike (bearings, forks, brakes). Put new suspension on the rear. Now I am fine tuning the carbs. I havent been able to get the carbs right yet. I have two burning about right (1,2) and two burning very rich(3,4). Does this sound right?? Back out air/idle misture screws to achieve maximum idle, 1 1/2 turns out on the adjustable jet on bottom of carb. Set float heights. Does that sound about right? How will the jet on the bottom of the carb effect the way the plugs burn??

[Anonymous]

Thanks for the info......what does that fuel needle jet do? Does it only effect idling? Or does it have bearing on the over all performance. I already had my carbs sync'd. Will adjusting the jets on the carbs effect that?? Or am I safe to go ahead and mess with the jets and not worry about the carbs being sync'd???

Thanks in advance

[earlfor]

JoCo, the pilot fuel screw regulates the amount of fuel that is allowed through the idle circuit. It is an idle range setting, but it never shuts down. when throttle is advanced into midrange, the idle jet with its pilot screw setting is still contributing to the overall mixture (as it does throughout the carb's operating range. At idle, it provides 100% of the fuel flow needed, as rpm increases and more fuel is required, though it is still flowing 100% of ITS capability, that portion is only a small percentage of the overall amount of fuel required. So, it does have an effect always, but in upper rpm ranges, it is minimal and you may or may not notice it, depending on what your settings are.

(will adjusting the jets on the carbs effect that?)
Adjusting the idle air screw and the pilot jet needle settings (both of which contribute throughout the carbs operating range) will to a slight degree alter the overall mixtures, but will not cause an imbalance in vacum. When synching the carbs, the vacum balance is acquired by adjusting the slide positions. When the engine is running at idle, there is no throttle advance and consequently, the slides are not raised.

am I safe to go ahead and mess with the jets and not worry about the carbs being sync'd

Yes, you may adjust the idle air screw and the pilot screw.
That will not cause the carbs to go out of sync.

Earl

Thanks for the info......what does that fuel needle jet do? Does it only effect idling? Or does it have bearing on the over all performance. I already had my carbs sync'd. Will adjusting the jets on the carbs effect that?? Or am I safe to go ahead and mess with the jets and not worry about the carbs being sync'd???

Thanks in advance