help needed. wont start after working before

[5t341th]

i get powerful backfire coming out of the carbs through the intake side. i open the intake box and try to crank my engine. it causes a loud pop and a puff of white smoke.
wtf going on

[5t341th]

okay some news!
i got it to start, it would start with choke on. when i close choke, it dies.
if i use the idle screw to adjust idle too high, the bike wants to die. so i leave it in the middle. if i turn off choke it dies. if i gas it, it dies. i feel that its too rich right now. what can i do to lean it out? idle mix screws has been set at 3 turns out, 2.5 turns out, 2 turns out, and 1.75 turns out.
whats the correct direction to turn to lean it out?

[BassCliff]

Hi,

Have the carbs been properly cleaned using the guides on my little website? If so, have they been bench synch'ed? Then comes vacuum balancing. Look in the carb sections of my website for more info.

I think I read where you said the air filter doesn't fit too well. These bikes do not tolerate air leaks in the intake system. See the Air Intake Repair and Airbox Sealing guides on my website.

I believe you are speaking of the "idle mixture screws" on the carbs. These adjust only the amount of the idle mixture as the mixture itself is pre-set within the carb. Start with all of them about three turns out from lightly seated. I say lightly because the tips are easy to break if you screw them in too tightly. Turning them in delivers less fuel and turning them out delivers more fuel, but ONLY at idle. Once you turn the throttle this "fuel circuit" is no longer involved.



Repair the air intake system. Adjust the main idle speed knob so that your bike idles somewhere around 1000-1200 rpm. Then adjust the vacuum balance, using the proper procedures. Then use the "highest idle" method to set the idle mixture screws. This is all after a proper cleaning, of course. You'll find documentation covering all of these procedures on my little website. Keep us informed.


Thank you for your indulgence,

BassCliff

[5t341th]

thank you guys for all your help. i got it running again. she runs beautiful.
i also just received my morgan carbtune so tomorrow i can sync it.

a new problem arised i think.
the petcock in the "run" position seems to kill the bike. i was riding in traffic and it died when i took off. turned it to "prime" and started up and ran great.
seems i gotta fix the petcock now. what do you guys recommend? petcock rebuild kits or a brand new petcock? seems like its a $30 difference.

also, will leaving the petcock on prime overflow my carbs? shouldnt the float level stop the petcock from feeding any more fuel into it?

[lonerider00]

shouldn't be a problem leaving it in prime. just make sure you turn it off when you park... floats do weird things when the bike is leaning on its side stand... Mine doesn't have a prime position, it's either in "run" (which puts the pickup about 2" from the bottom of the tank) or "reserve" (which puts the pickup at the bottom).

Also, I rebuilt mine because I like the vacuum shutoff; but like I said before, since the rebuild, the starter won't generate enough vacuum to engage the petcock; I need to "prime" the carbs by hand... or mouth as it were... come to think of it, this might be similar to your problem... check your vacuum line to the petcock; then disconnect your tank, suck on the vacuum side and see if any fuel comes out, or you could buy a new one without the vacuum system, if you do be sure to block off the vacuum nipple on your #2 carb otherwise things will never run right.