Kawasaki Vulcan Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter #1
Hi all,

Need some help with my 93 Vulcan 750. I've always been in awe of the vast amount of experience and knowledge on forums, and I've gotten as far as I have on this bike by being a lurker here, but I need some direct help now if anyone can spare it. I bought it from someone who didn't know a lot about working on bikes, but was gung-ho about doing so anyway. I keep finding little time bombs from him.

I've got it running at this point, but it runs absurdly rich. As in, gas vapor out the exhaust rich. I've meticulously cleaned the carbs, the floats are set right (and verified to be right with tube from the drain screw). The fuel petcock seems to be functioning normally (I've primed it several times with my mouth, I can see gas flowing until at some point it just stops, no gas leaking out anywhere). Gas is getting into the engine in excess, somehow, but I can't figure it out. I'm getting miserable mileage (like... 20ish miles per gallon), and the plugs are fouling within 20 miles or so. The bike starts to skip, once I brush the plugs off with a stiff bristle brush, it's back to running normally. The first time I did an oil change, there was a large liquid volume, and the oil smelled like gas. The main jet holders were smashed and holes in the side were closed off from that when I got the bike, and the coaster enricher diaphragms were garbage. Replaced those both in hopes it would make a difference, but it doesn't seem to have. I'm not averse to rebuilding the petcock, but it doesn't seem like it needs it right now (I've seen that as advice to cure a rich condition many times while lurking).

The bike is marbled, has stock exhaust, has the stock jets (unless they have been drilled).

I'm tearing my hair out with this problem, please help!
 

·
Registered
Joined
·
11,754 Posts
1. Fuel in the oil means that fuel tap is leaking, no matter what your lips are telling you.
2. Tear down carbs and compare what you have to parts diagram to make sure everything is present and accounted for.
3. Make sure floats are not sinkers.

Post back with what you find.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #3
1) Well, I'm not one to argue with experience. It sounds like you have seen this many times before.
2) Have done this, Everything is present, installed correctly, and clean.
3) Floats are still sealed and are keeping level at the correct place.

Time for a petcock rebuild then I guess. I'm sure I can find that kit on a popular online auction site, but is there a better choice? Is this a case where buying a whole new petcock is the right choice?

Since I'm getting plug fouling in both cylinders, how would excess gas be getting into the rear cylinder? The float valve seems to be working properly as verified by float bowl level. The vacuum port that would normally go to the air actuated valve in front of the battery is capped off. The petcock gets its vacuum signal from the front cylinder carburetor.

I'll be checking compression today just to make sure I don't have signs of excessive blow by on the rings, but given it's performance when I took it out, I'm not inclined to think that is the issue. (though if I keep running it this rich, it will be an issue mighty quick when I wash the lubrication off the cylinder walls with gasoline). I haven't been driving it around other than that one day, and I'm not inclined to until I get this flooding issue under control.


Thanks for the response!
 

·
Registered
Joined
·
7 Posts
Discussion Starter #5
After discussing it over at VN750.com, I eventually came to the nuclear option. A significantly damaged carburetor body. Turns out the PO had cranked the emulsion tubes ALL the way in (no threads visible). The result was that he cracked the carburetor bodies up inside where I couldn't see. I picked up a set from a salvage yard for $75. After swapping all the guts into the new carb bodies, I got it installed and I'm no longer blowing gas vapor or running rich. I still have to do an oil change before riding it though. Gas in the oil is definitely no good.
 

·
Registered
Joined
·
7 Posts
Discussion Starter #7
I would have stood a better chance at solving it if I was more experienced with Vulcan 750 carburetors. When I pulled the main jet holders and found them smashed, I assumed that had happened to them outside the bike. Now I know those spin in until they bottom out, and no more. (Here's a picture of the smashed holders alongside some new ones).
 

Attachments

1 - 8 of 8 Posts
Top