another jetting question. not starting

[Guest]

first off i have a 1980 gs 750 i recently re jetted with a stage 3 dynojet kit. i have pods and a 4-1. it was running starting up fine before this. but now it just wont start. i have fuel in all the bowls. and when i spray some starter fluid past the pods it will run off that for a second. so i know its firing and getting fuel. but could it be the needle settings? its set to the 4th groove from the top as per the dynojet instructions. im also running the 130 main jets.

[Steve]

You don't even need to have needles and mains installed to start the bike.

What you NEED is fuel and air through the pilot circuit, which includes the pilot air jet in the intake throat, the pilot fuel jet in the bowl and the idle mixture adjustment screw, on top of the outlet of the carb.

Just because you have fuel in the bowls does not mean that it is getting through the small passages between these jets and screws, then into the engine.

.

[bartmancometh]

so what exactly can i do to fix it? how do i know if my pilot circuit is working correctly. i did have it running a few times after i re did the carbs. but it was just sitting in the garage.

[Steve]

Have you ever done the full "strip and dip" carb cleaning, along with o-ring replacement?

If not, this is the perfect time to do it.

If you have, apparently something has gotten in to plug something up, so at least open up the carbs and blast a little bit of carb cleaner spray backward through the passages to dislodge whatever is in there.

.

[tom203]

You sure your "choke" is working, as in hooked up and pulling out those plungers enough?

[bartmancometh]

choke is all hooked up and seems to work correctly

[bartmancometh]

so i just broke down the carbs again and made sure all the passages were clear. put it all back together and still nothing. i had just gotten new o-rings the other day. so all the seals are good. and all the vacuum lines are hooked up too. these carbs are as clean as a whistle and tight as a ducks .

[chuck hahn]

Are there NEW rubber plugs in the pilot jets holes? I am assuming these are CV carbs.

Have you double checked the float heights and do this without gaskets on the carbs?

Sure all the float needles move up and down smoothly as you manually lift and drop the floats? Visually see that they do?

Vent holes ARE NOT capped of?

[almarconi]

Try blowing into one of the carburetor vent tubes, apply full choke and see if it will start.

[bartmancometh]

so i went through the carbs again. made sure all the passages were clear and put it all back together and still nothing.

[tom203]

If you crank it for a while with "choke" applied, your spark plugs will appear wet. If they aren't, then the "choke" passages are blocked. Look at little orifice in bottom of each fuel bowl-this feeds this "choke" system and this gets blocked easily.

[almarconi]

Try blowing into one of the carburetor vent tubes, apply full choke and see if it will start.

Can you hear me now?

[BassCliff]

Hi,

Have the carbs ever been properly cleaned and a new set of O-rings, from http://cycleorings.com, installed?

For reference:
Mikuni BS(CV) Carburetor Rebuild Tutorial
(Mr. Nessism)
CV Carburetor Rebuild Guide
(Courtesy of GSR and John Bloemer)
(Click here to see the CV Carb Notes)

Was is running properly before the modifications? It's a little more difficult to get things configured properly if there is no baseline to work from.

Thank you for your indulgence,

BassCliff

[bartmancometh]

basscliff- the carbs have been dipped cleaned and fitted with new o rings as per your website tutorials. they really help alot thank you.