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Discussion Starter #1
1995 Vulcan 88 (1500a1).
Basket case, I’ve been unable to start the bike since last ride. She stalled out on me when I pulled the clutch in my driveway.
I have since replaced float valve needles. All rubber seals, most of the hoses. Full petcock rebuild. New battery. New spark plugs. New fuel filter. New fuel (after attempting to run both sea foam and gumout, separately of course).
When I blow starter fluid through the air box she will start, aggressively; as if open full throttle immediately. But only for a quick second then dies.
All plugs getting spark. It is sucking air.
It sounded like a fuel delivery issue to me.
Tore down and cleaned carbs, again! Double...triple checked float height. It meets specs both apart and on bike measuring per manual.

Now, while trying to start it it runs fuel out of the “carb air breather hose” (as labeled in the manual).
When I block the end of this hose with my thumb I can get the motor to “chug” but not start or run. And fuel still drains when later uncovered following attempt to start.
I cannot find in the manual where this hose should connect (if at all. It appears to drain right out the bottom). And why am I getting fuel out of it?
The hose is #5, and #6 is the connector in the enclosed pictures.
 

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Fuel is coming out the hose as the float chambers are filling and the fuel has to go somewhere. It is also in your oil. If you changed the float needles and adjust float heights then look at the way you are trying to start the bike. Those Keihins have enricheners; keep you hand OFF the throttle. The carbs are flooding and I suspect you are cracking open the throttle. Next, consider new slow jets, change the oil and give it another shot at starting.
 

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Discussion Starter #3
You are right. I have played the throttle while trying to start. Never to begin though. Usually after attempting to crank it for a while. But I have since replaced the oil. I know carbs that overflow will flow into the cylinders. I assumed that was what happened. That too is why I rebuilt the petcock and replaced the float needles.

So if understand you correctly. I need slower jets? I don’t understand how the bike can go from running to not being able to start due to needing slower jets though?
 

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Slow jet (aka pilot jets). The slow jets are what allows the bike to idle. The bike will start on full choke but not maintain any idle if the slow jets are clogged. Not much point in trying to clean jets in my opinion but some do. Sticking wires with serrated edges into jets is really a bad idea.
 

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Discussion Starter #5
I see what you’re speaking about now. However the bike hasn’t started since the day it died. That’s going on at least 2 months of attempting to start. With and without throttling. Rebuilt carbs etc.
if it died due to clogged or bad slow jets, what would cease it from starting following it dying?
 

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Discussion Starter #6
Update, recleaned the carbs again. Redid the spark plug wires again.
Tried to start this morning, bike quickly killed the battery (which remains on a tender at all times). Used second battery to jump it.
It was very slow to start. It had an increasing chug (like a train accelerating from stopped) before it finally took off, it did this every time I attempted to start.
I never touched the throttle, but fuel is still pouring out of that breather hose. 6 oz total from startup and allowing to run about 3 mins.
White smoke from the exhaust.
If I give it throttle it dies when released. Then hard to start again.

I’ll be replacing the battery next.

Any other thoughts?
 

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Discussion Starter #8
Not yet. I had surgery today; haven’t had any time to get out there. I began tweaking the pilot screws again, and I was getting seemingly better response. But I won’t know for sure until I can spend the time out there. Probably a day or two from now. I don’t believe syncing them would have this much of an effect on in ability to start? And I’d need it running or turning over successfully to sync them up anyway. I have bench tested them. And they were good at the time.
 
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