awe man..... wait, where's that go? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 4 (permalink) Old 07-22-2015, 07:08 PM Thread Starter
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awe man..... wait, where's that go?

sorry if this is addressed somewhere else, if it is then I haven't found it yet so here goes.

the other day I was heading down the road on my 02 Vulcan, running like a top, when it suddenly bucked maybe twice and then lost a considerable amount of power.. I was low on gas so I assumed out of fuel (I just got the bike and haven't ridden it enough to know where "put me on reserve" is on the gauge) unfortunately turning to reserve didn't fix it and neither did filling the tank at the next gas station (1.5 miles down the road). it still ran but was an absolute DOG and it was all I could do to hit 60. I made it home like this and found that the vacuum hose on the rear carb was disconnected (pulled away due to being too short). assuming this was the culprit I replaced this hose with a new piece and stuck it on where I guessed it went but it still won't run worth a darn.. if one pinches off the vacuum hose or blocks it in some way the bike immediately idles perfectly but still won't rev up right. if the hose is just left to hang and/or just simply plugged into the little valve thingy I thought it went to the bike barely starts and only runs (poorly) under choke. further investigation revealed that the airfilters are both completely deteriorated and I don't know much as to how long the bike sat before I got it (bad fuel is unlikely because I put three tanks through it before this happened) but maybe rust in the tank?

so my first question is: where is that vacuum hose supposed to go? when I was trying to fix the old one it popped out and because I hadn't taken the seat off yet I have no clue what it had been attached to. it looked like it went to the emissions valve under the back of the tank maybe? but it won't run if I plug it into that..

second question: what else could have caused this condition? i'm going to clean out jets and check spark plugs tonight.. i'm afraid I may have sucked in a piece of one of the filters.
just looking for other ideas of things to check if this doesn't fix it..

side notes:
This problem occurred the first time I have ever let the bike get low on gas.

seems like it may only be running on one piston when revved up.. but that's a wild swing, I'm not that good at auditory diagnosis.

i'm completely lost.. any help would be fantastic, thank you in advance
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post #2 of 4 (permalink) Old 07-22-2015, 07:48 PM
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Sounds like you got some crud in your carbs. My suggestion is to get a Clymers manual, buy new filters and pull the carbs. There's a good youtube video that Roach has for cleaning the carbs & jets.

"Show me a man who makes no mistakes, and I'll show you a man who doesn't do things." Theodore Roosevelt."

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post #3 of 4 (permalink) Old 07-22-2015, 11:36 PM
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Originally Posted by shark88 View Post
Sounds like you got some crud in your carbs. My suggestion is to get a Clymers manual, buy new filters and pull the carbs. There's a good youtube video that Roach has for cleaning the carbs & jets.
Second this. Either from the deteriorated filters or trash in the tank at low fuel level. Post back when ya get it going.

As for the vacuum line, sorry but I don't know. And I sold my 750 a week and a half ago or I would look and see. Hope ya get it.

2005 Vulcan 1500 Classic FI

Previous bike: 2002 Vulcan 750
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post #4 of 4 (permalink) Old 07-23-2015, 05:58 AM
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If the bike is stock, the vacuum line on the rear carb goes to the air valve under the seat. The other vacuum line goes to the petcock.

Had a very similar problem, went to reserve one day and pulled trash into the front carb due to the reserve filter screen missing. This was causing the front cylinder to flood. Pull a plug on both cylinders and see if its flooded. If so you can try the blowback method but you may have to pull the carbs. While the tank is off remove the petcock and make sure both filter screens are in place and inspect the tank for debris. Good luck with it.

2002 VN 750, stock except for accessories
Mustang seat
Super Bright LED brake strobe on trunk
About 25k miles
All drive train maintenance performed, drive shaft coupler replaced
Way more experienced at pulling VN 750 carbs than I ever wanted to be.
TOC ACCT rebuild kits installed
Pick up coil mod
Cooling system flushed, refilled with fresh coolant
Petcock rebuilt
VN sold, current steed Honda ST 1300
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