Kawasaki VN750 Forum banner

1 - 20 of 40 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter #1
I've been working on an 86 750 with 15,500 miles on it.

First thing I did was run Sea Foam in the tank through the bike.

It was running okay, but there was some issues with it. One of which was a petcock that was seeping fuel through the spacer block and diaphragm. Also, there was a large crack in the air box which was letting in tons of unfiltered air.

Today, I rebuilt the petcock with all new O-rings and this cleared up the seep from before. There was a small drip of fuel coming from the outlets. Maybe the spring needs to be replaced also? On prime, it really flows though.

I also replaced the air box.

When I fired it up. I started to get fuel from the front of the carbs pretty heavily. I am sure I hooked up the hoses back correctly as I marked them. This had never happened before with this bike.

Is it possible that the mixture screws had been set to offset the amount of air from the cracked air box (main duct) and that's why the fuel overflowed? Or, do I now have a stuck float also?

Again, this had never happened before. So, all of a sudden a stuck float?

Thanks for any help guys!

Sincerely,
David
 

·
Registered
Joined
·
29 Posts
Discussion Starter #3
I think it was leaking from just the front of the carbs. So, that's the left?

Would Wolfie's method work on this potentially?
 

·
Registered
Joined
·
7,900 Posts
Could be a stuck float. Try a few solid raps with a plastic screwdriver handle on the side of the bowl.
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,080 Posts
I think it was leaking from just the front of the carbs. So, that's the left?

Would Wolfie's method work on this potentially?
would not hurt to try.

Sent from my LGL34C using Tapatalk
 

·
Registered
Joined
·
29 Posts
Discussion Starter #6
Hey, good news! I found the source of the fuel leak. It is a one of the fuel hoses with a giant crack. I couldn't see it when the tank was in place. So, I placed the tank on loosely, fired it up and stuck a flashlight inside and you could see fuel pumping out of it.

So........any chance of replacing the hoses without pulling the whole carb out?

Thanks!
David
 

·
Registered
Joined
·
736 Posts
as long as the fittings going into the sides of the carbs aren't bad, then yeah you can replace the fuel lines. Take the tank off and it should be a lot clearer how to access them. might be a bit of a struggle still if you have the stock airbox in place, but not impossible.
 

·
Registered
Joined
·
29 Posts
Discussion Starter #8
Most of the lines look good actually. The problem was, the routing of that one line was rubbing against the hard edge of the top carb bowl and it finally just tore when I was moving them around to attach to the petcock.

Now, the issue is routing. Right now, the line is a little too tight and causing a restriction to the fuel. This is indicated by tilting the bike upright from the side stand and hearing the idle get stronger.

Are there any photos here of people's line routing?

Also, should the petcock nipples be aimed down; 45 degrees; 90 degrees; etc? for best fuel flow?

Thanks!!!
David
 

·
Super Moderator
Joined
·
2,570 Posts
on my petcock, stock, never molested to the best of my knowledge... one points down, one points up.. of course, the one that points upwards is the frontmost port.

I would say both angles are less than 45 degrees from horizontal
 

·
Registered
Joined
·
736 Posts
Both of my petcock nipples (what a fun phrase) point directly horizontal towards the carbs
 

·
Registered
Joined
·
39 Posts
Most of the lines look good actually. The problem was, the routing of that one line was rubbing against the hard edge of the top carb bowl and it finally just tore when I was moving them around to attach to the petcock.

Now, the issue is routing. Right now, the line is a little too tight and causing a restriction to the fuel. This is indicated by tilting the bike upright from the side stand and hearing the idle get stronger.

Are there any photos here of people's line routing?

Also, should the petcock nipples be aimed down; 45 degrees; 90 degrees; etc? for best fuel flow?

Thanks!!!
David
I struggled with this myself. I eventually found that both nipples tilted approximately 15-30 out from the bike (relative to straight down) worked for me. That allowed me to run fuel hose (I picked up the clear "lawnmower" stuff from advance auto), along with an inline fuel filter for each line. It looks like it's way out in the wind, but with your feet on the controls, you are definitely well clear of them.

I was able to get the lines on without taking the carbs off this way, but it took a lot of fiddling to get the lengths right. And the shorter your filter the better. The ones I have are pretty coarse mesh, and really would only catch flakes of rust, but I figure it's better than nothing.
 

·
Registered
Joined
·
39 Posts
As an aside... this is also in part to make removing the tank easy for me, because I'm still troubleshooting A LOT of stuff. Also to give me room for inline fuel filters.
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,080 Posts
Both of my petcock nipples (what a fun phrase) point directly horizontal towards the carbs
hehe hehe he said petcock nipples. hehe hehe

Sent from my LGL34C using Tapatalk
 
  • Like
Reactions: ubertalldude

·
Registered
Joined
·
29 Posts
Discussion Starter #15
This may sound like a dumb question; but I've been looking at the diagrams for hose/vent lines off the carb. And, I'm starting to think that my bike's hoses aren't connected correctly.

I hooked things back up the way they were, but I think they may have been wrong when I got it.

Is there a T-connector on any of the fuel lines that go to the petcock? Or, do they go directly from the carb fitting to each side of the petcock? This is a stock 86 petcock with PRI, ON, RES.
 

·
Registered
Joined
·
7,900 Posts
One fuel line from each carb, straight to the petcock.

The lines with the tee should be the vents. One vent from each carb into the tee, one hose out to the ear (or placed out of the wind). Vent hose stuck in the ear hole needs cut at 45° on the end to prevent blocking against the back of the ear.

You'll want to make sure the fuel lines are not connected to vent ports. It can work that way, but not real well.

There's a vacuum port on each carb, left side goes to the center port of the petcock, right side goes tot he emissions valve under the seat.
 

·
Registered
Joined
·
29 Posts
Discussion Starter #17
Wow, well this might explain a bunch of the issues I've been having with this bike!

I am pretty sure the PO had the vent hoses on the T connected to one side of the petcock!

I just went out and corrected the issue and can't wait to try and fire it up tomorrow.

Thanks for the confirmation.
 

·
Registered
Joined
·
29 Posts
Discussion Starter #18
Confirmed! Somebody who had done work on this bike previously (not me thankfully) had connected one of the fuel petcock connections to the vent ports on the carb!!

Changed it last night and turned air/mixture screws back to 2.5 turns. Fired it up this morning with 1/2 choke and barely a press on the start button. No rough start; had to adjust idle a bit. Warmed it up, no backfires, not throttle to start it.

Took it around the neighborhood, no issues.

Drove about 5 miles away; parked it for 40-50 minutes. It fired right back up, no warm start issues. Drove it another 3 miles or so and shut it down. 20-30 minutes later; no issue with warm start again!

Strong performance; no chugging or backfiring/popping on deceleration. Felt solid, strong and rode like a brand new bike.

Poor bike was starving for fuel!

So, my question would be; is there any legitimate reason on a bike with 15,000 miles that someone would intentionally route the fuel line to the vent on the carbs???
 

·
FREEBIRDS MC CENTRAL NY
Joined
·
16,080 Posts
maybe they had carbs off to clean and hooked them up wrong

Sent from my LGL34C using Tapatalk
 

·
Registered
Joined
·
7,900 Posts
maybe they had carbs off to clean and hooked them up wrong

Sent from my LGL34C using Tapatalk
Yep, jamming those carbs back in, trying to see paradise by the dashboard light, felt around and found a nipple and poked the hose right on it. >:)

I twisted the nips on my petcock so they point straight in at the carbs.

Sounds like you're on the road again.
 
1 - 20 of 40 Posts
Top