Prime, Choke, Throttle

[ybot1966]

My GS750 seems to need massaging before it will kick start, how long should prime be turned on to fill carbs and should the throttle be left alone completely. My bike seems to need alot of choke to fire.

regards

Toby

[1948man]

You shouldn't need prime every time if the bike is run fairly often. If it has been sitting, maybe prime for a minute before cranking. Leave the throttle alone and choke. If it takes a lot of choke be ready to adjust the choke if the rpms go too high. Sounds like it's lean. Maybe needs intake boots or at least intake O-rings. Is the exhaust and air intake original or aftermarket?

[ybot1966]

1948man

Exhaust four into one, got K&N air pods, i cant use it regularly so it sits for about a week between starts. I use the prime just to get fresh fuel in the carbs but wasnt sure how long it takes to fill. When it starts it doesnt need the choke for long. I heard with the vacuum taps that the trottle should be left alone, although on some forums some say to open the throttle slightly on starting? I wonder if without the standard air box the weight of the carbs may lossen the seals

[Dave8338]

Did you do the pods and the 4-1 exhaust?

Does it run well after you get it started and warmed up?

When was the last valve adjustment?

[ybot1966]

pods and 4into1 already on when bought, its ok once running, it probably needs valves adjusted as it only done 1.5k in five years, once the clocks go forward i will need to exercise it more to see whether its consistent in running.

[Steve]

. I heard with the vacuum taps that the trottle should be left alone, although on some forums some say to open the throttle slightly on starting?

It has NOTHING to do with the vacuum taps, it is entirely up to the "choke", which is really an "enrichening system", since it does not physically block the opening of the carb. It opens separate air and fuel passages, then relys on the high vacuum of the closed throttle to pull air and fuel through them. If you open the throttle AT ALL, you destroy the vacuum and force it to try to run on the normal, LEAN mixture.

.

[tatu]

1948man

i cant use it regularly so it sits for about a week between starts. I use the prime just to get fresh fuel in the carbs but wasnt sure how long it takes to fill.

A week between starts should be ok, when I leave my bikes I disconect the vacuum pipe and block it with a 6mm screw and run the carbs dry just as the motor starts to die I add choke and take the revs up to suck as much of the fuel out as poss, I do it every time I'm ready to go away, be it long or short aways. It saves messing with draining carbs down and gumming issues. So start ups are easy.