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Discussion Starter · #1 ·
Ok so I have an 85 nighthawk 450 just picked it up the other day... the guy I got it from had it for 2 years and was never able to get it to start.. so today after checking if I had spark I squirted fuel into the carbs and it started and ran for about 30 seconds (sounded great btw)... so first thought see if the carbs are getting fuel! Come to find out they are! Just the fuel is not getting in for some reason... so my question is what could stop the fuel from making it into the carb??
 

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Pull the carbs, clean the jets thoroughly. Fuel has to make it through the carbs to get the intake.
 

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Check to see that you have fuel flow from the petcock into the carb set from the gas line hose. Just remove the hose from the petcock and open the fuel valve and hopefully the fuel is flowing out of the petcock and tank. Next check is to see if there is gas in the float bowls of the carbs and there should be overflow black rubber hoses connected to the drain nipple on the bottom of the carbs. If you only have a nipple on the bottom of the float bowls because someone removed the hoses then place a small container under there to catch any gas that drains out. There is a small flat blade screw that need to be opened on the float bowl for this procedure.
If you pass both of these above tests then there appears to be gas in the carb float bowls. The carbs maybe dirty and in need of good cleaning to get the gas to be processed correctly for the bike to run. There should be a procedure on cleaning the Honda VB series carbs here on the forum if your not familiar with carb cleaning.
 
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Discussion Starter · #5 ·
Check to see that you have fuel flow from the petcock into the carb set from the gas line hose. Just remove the hose from the petcock and open the fuel valve and hopefully the fuel is flowing out of the petcock and tank. Next check is to see if there is gas in the float bowls of the carbs and there should be overflow black rubber hoses connected to the drain nipple on the bottom of the carbs. If you only have a nipple on the bottom of the float bowls because someone removed the hoses then place a small container under there to catch any gas that drains out. There is a small flat blade screw that need to be opened on the float bowl for this procedure.
If you pass both of these above tests then there appears to be gas in the carb float bowls. The carbs maybe dirty and in need of good cleaning to get the gas to be processed correctly for the bike to run. There should be a procedure on cleaning the Honda VB series carbs here on the forum if your not familiar with carb cleaning.
I will give it a whirl thanks!!
 

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When you say fuel is getting to the carbs, what are you checking? You have fuel at the hose that connects to the carbs? You open the drain valves and fuel comes out?

If you attach a clear line to the bowl drain nipples, hold the other end of the line up alongside the carb, then open the drain screw you can see what the fuel level in the bowl actually is.

If the fuel level in the bowls is correct you likely do have plugged fuel passages. If you're going to take the carbs off to clean them, just as well do it right:

http://www.hondatwins.net/forums/63-fuel-supply-carburation/24191-rebuilding-vbulletin-carbs.html
 

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Discussion Starter · #7 · (Edited)
When you say fuel is getting to the carbs, what are you checking? You have fuel at the hose that connects to the carbs? You open the drain valves and fuel comes out[/url]
I'm chthe main fuel beneath the fuel selector switch the on e that says on off and reserve fuel comes out there
 

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It's possible that the float valves are stuck or obstructed and are not allowing fuel to enter the carbs. If you open the float bowl drains on the bottom of the bowls fuel should come out.
 

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Discussion Starter · #9 ·
It's possible that the float valves are stuck or obstructed and are not allowing fuel to enter the carbs. If you open the float bowl drains on the bottom of the bowls fuel should come out.
I am gonna pull the carbs off and take them apart to find out the previous owner said his buddy took them off and cleaned them but who knows how deep he went
 

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When I bought my 450, the seller said he cleaned the carbs out. When I took a shot at starting it, it promptly dumped a stream of gas on the floor out of overflows :D I tend to assume anything the seller did should be redone these days.
 

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Ok... call me a A--HOLE....
BUT... is there any fuel in the tank???:) :)
And YES, there is a reason I say that ... don't ask my why..
 

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Discussion Starter · #12 ·
When I bought my 450, the seller said he cleaned the carbs out. When I took a shot at starting it, it promptly dumped a stream of gas on the floor out of overflows
I tend to assume anything the seller did should be redone these days.
I can see that every time I look at this bike I find something else ridiculous!
 

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... so EXACTLY how long ago did the PO "clean out" the carbs? And what did he use? A garden hose!?!?
 

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Discussion Starter · #17 ·
... so EXACTLY how long ago did the PO "clean out" the carbs? And what did he use? A garden hose!?!?
Quite possibly!! Screws were loose choke cable shot vacuum lines missing! I'm no mechanic but even I know better than all this mess! Lol
 

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Discussion Starter · #18 ·
Start here:

http://www.hondatwins.net/forums/63-fuel-supply-carburation/24191-rebuilding-vbulletin-carbs.html

Finally resolved my confusion<img src="http://www.hondatwins.net/forums/images/smilies/confused.png" border="0" alt="" title="Confused" class="inlineimg" />, thread
moved to SOHC fuel section.

If they're as bad as that picture looks and you don't have much carb experience, you might consider looking for new carbs.
Thanks! Yeah I'm not very experienced but I'm persistent I am a crane operator so I brought the carbs to work with me and one of the mechanics is gonna hook me up with a a good cleaning and make sure everything is put back together correctly
 

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Discussion Starter · #19 ·
Ok well I've got the floats fixed and cleaned the carbs the bike runs! But... it pours fuel like crazy out of the carbs float bowl seal and the over flows so I ordered a rebuild kit for the carbs and am going to do that this weekend! I am so stoked everything is working out very well so far! I put insurance on it and got my historic tags yesterday.. all that's left is the front brake the previous owner removed the caliper and now the pads are pressing against each other any suggestions on how to fix this issue? my plan. Is to crack the bleeder and see what happens... thanks for all your help!!! The picture is my big helper laying out everywhere the carbs are leaking
 

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Spending time with your favorite mechanic... you can't put a price on that! Do yourself a favor, take lots of pics and tech him every chance you can!!
 
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