bike wont start, very confusing

[sparty]

i apologize in advance for the length of this post, but i'm having some serious trouble with my bike. i've never had it running before and i've been rebuilding it for the last two months. the problem i'm having is in the carbs, or at least i'm 90% sure it is. i picked these carbs up from a salvage yard and pretty much replaced everything that needed to be replaced and cleaned everything else out.

i know the bike will run because it will run with starter fluid, so right there i know theres compression, and spark. the battery has been completely charged multiple times by myself and interstate batteries, and the carbs are getting fuel into the float bowls. i also made sure the little brass tube was cleaned out because when i shot brake cleaner into the hole in the choke, it dripped out of that tube, so that passage is clean.

now my question is, what other options do i have to explore? i've cleaned everything that i could see that could be cleaned, and as far as i know all of the pieces are there and in working order, so i need a carb expert to tell me why the bike won't crank, i'm not even concerned about tuning them right now, just getting it started. thanks, -Andy

[Bagged_camaro]

does the bike crank over? Are you saying its not cranking at all?

If its cranking, and just not starting...have you adjusted your air/fuel screws on the carbs? As well, are you using proper gaskets for the float bowls? If not, theyll suck in air and lean out the mixture to the point of not running.

You might need to adjust the float levels too.

G

[sparty]

i've gotten new gaskets and i've adjusted the floats over a wide range of settings, still nothing. i've gotten it running with starting fluid through the carbs, so it can't be the engine. WHY WONT THIS WORK???

:edit: also the air screws and what not, not adjustetd just open.

[veggibooter]

ya pelase somone help him cause mine does the same phucking thing and it is making me very angery and i would liek to know

[Bagged_camaro]

take off the tank, and open the fuel cock to prime. Fuel should flow freely. Check tank to fuel filter line for blockage. Replace fuel filter. Check fuel filter to carb line for blockage.

If thats all ok, you know youre getting gas to the carb. From there on its all carb, and nothing else. Buy a carb sync tool (weird looking device that measures fuel flow) then you can balance all the carbs equally from there.

Remove every jet, needle seat, floats and clean them all. Place floats in a bowl of gas to check that they still do float, and are not water logged. Soak carb in carb cleaner concentrate over night (Only the bottom of the carb!!!) and then blow out the next day with compressed air.

Reassemble with NEW gaskets... DONT use gasket glue!!!.
lightly screw in the pilot air screws and the outside of all the carbs... then back out one full turn for a preliminary setting.

If non of this works...take it to a proffesional and cough up the dough to get it done right.

G

[87gsxrnut]

Check your vacuum line. If it is leaking, or not hooked to the petcock, the carbs will get NO gas. When you were rebuilding, did you take it off and hook it up incorrectly? There are also some OPEN ports on the front top of some Mikuni Inline-4 Carbs. They should NOT be capped off w/rubber vacuum plugs (they look like they should, but NOPE). If they are, well, your bike will NOT start at all, even if everything else is hooked up correctly. Don't ask me how I know this.

Also, BUY A FUEL BOTTLE. Then, you can cap off your vacuum line, and experiment w/the tank off the bike.

If you don't have the manual already, GET ONE!

Also, what type of bike is it? Does it have an electronic fuel pump? I have seen guys (namely ME) hook the fuel pump lines backwards. Took a while to figure that one out.

Like G said above, check your fuel filter, and make sure it is FLOWING in the correct direction and not plugged. Sometimes the easiest fix is the correct fix.

- Nut

[sparty]

the bike is an '86 GS450, no fuel pump, and i'm absolutely positive fuel is getting to the carbs. everytime i hook the carbs back up, i check the screw at the bottom of the float bowl to make sure that there is fuel in there, and there is every time. i feel like i've already majorly cleaned them more than once, but i guess one more really good time can't hurt. other than that, is there anything else that it could be? and how much am i looking at to take it to a pro.

[87gsxrnut]

Did you pull the main jets, and visually inspect them w/a light source? How about the pilot jets? Sounds like your carbs might need an "off-the-rack" soaking then cleaning. Did you spray all the vents, ports etc w/cleaner, then hit them up w/compressed air? I have a set I am working on like this now. Don't run for crap below 8K ('86 GSX-R 1100 34mm CVs).

They were a total mess when I got them, but they are coming along. Eight months underwater will do that to a set of carbs

- Nut

[veggibooter]

is fuel supost to come out of bothe sides of the fuel cock i have 2 gas lines and a vacum i have a dif bike but same problem

[sparty]

okay, i was thinking, maybe the carbs arent creating a vacuum thus not drawing up any fuel into the venturi. if this is the case, what could be causing the problem? and if not, am i out of options?

[sparty]

things got more interesting, i went on the vacuum theory and figured out that the butterfly vavle was not shutting all the way, so i loosened the throttle cable and it shut. to make a long story short, the bike actually started when i took the fuel tank off, but more importantly what i think is the vacuum hose. when i reattach that hose, nothing happened. it never ran for a very long time b/c i never left the petcock on prime, so it would just run the fuel out of the bowl and then die. so then the battery started to die so i charged it, when i put it back in i couldnt get it to start again, i tried recreating what had happened that morning, and nothing happened. this is starting to really bug me.