won't start-carb confusion!!!!!

[kurtj]

Back again!
I thank god for you guys, don't know what I'd do without all your help!

Had starting problems after restoring 1980 gs 750et. Opened prime and bike ran. Tested new vac petcock, runs like it's suppose to. Let sit over nite and wouldn't start at all. Been that way til I got home from work tonite to do some tests,

Crank all nite long, won't start.
pulled carb bowl plug, plently of fuel
pulled spark plugs, dry
tested spark plugs, sparks like the 4th of july!
Filled bowls on prime to MAKE SURE carb bowls are full, overflowed thru the carb vents so I know I'm there.

NOTHIN! Just cranks battery down.
I have spark
I have fuel going to the carb bowls
I DON'T have fuel going to ANY cylinders.

I Don't get it!

[GearHead]

Sounds kinda like a clogged passage in the carb. Look at the main jets and the idle circuit. Have you dissasembled the carbs and givven them a good cleaning? Any rust in the tank ect?

[Nessism]

What GearHead said...

Unless you pull the carbs all apart like the tutorial on the GSR homepage suggests, you didn't clean the carbs.

[kurtj]

I relined the tank with por 15. great stuff. The carbs were cleaned before I bought it. I pulled the carbs to set the floats cause I was running rich. Carbs are immaculate. New boots, new diaphrams. 3 out of 4 main jets were replaced.

[Nessism]

I relined the tank with por 15. great stuff. The carbs were cleaned before I bought it. I pulled the carbs to set the floats cause I was running rich. Carbs are immaculate. New boots, new diaphrams. 3 out of 4 main jets were replaced.

Did you pull out the pilot jets and hold them up the the light to make sure they are open? Did you replace all the various O-rings to make sure they are soft and will seal properly? Rubber plugs in place over the pilot circuit? There is more to a carb rebuild that looking inside the float bowls to see if they are clean.

[Steve]

I relined the tank with por 15. great stuff. The carbs were cleaned before I bought it. I pulled the carbs to set the floats cause I was running rich. Carbs are immaculate. New boots, new diaphrams. 3 out of 4 main jets were replaced.

Two flags raised when I read this.

1. HOW were the carbs cleaned? If you did not see that they were dipped and thoroughly poked, prodded, blasted, etc., you don't know FOR SURE that they are clean, you are only trusting what the previous owner told you. Did you find any other discrepancies in the description of the bike?

2. Carbs can look immaculate, inside and out, but be totally clogged in all the little passages where the gas needs to go through. Again, if you did not see that they were dipped, ...


One other prime suspect (sorry about the pun) would be valve adjustment. Tight valves make it very hard to start when cold.

.

[smoothbomber23]

Valve Clearance. I just did mine and all of them (intake and exhaust) were way to tight. The job scared me at first, but was very easy if you go look at the DIY on bikecliffs website. Also there is a possibility that this isnt the exact problem but you should do it anyway just so your bike is running the way it was built to.