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Discussion Starter #1
I am in the process of cleaning (and possibly overhauling) the carbs in my 500. As I was taking the carbs off the bike, I noticed that the vacuum hoses on L/R carbs are connected asymmetrically.

In my US model I have the suction valves installed to ensure burning off of any unburned fuel in the exhaust (to satisfy EPA requirements).

The Left carb vaccuum hose is connected to the output of a hub which connects to these same suction valves.
The Right carb vacuum hose connects directly to fuel tank's vacuum outlet.

Photo of the hub attached - I may have misunderstood and mislabeled the parts. But the hub shown has an outlet that connected to a hose then connected to the vacuum hose input of the Left carb. Please advise! Thanks!

Does this sound right to you guys? In addition (I don't know if this is relevant info) my tank is from Vulcan 800 so it has a few more vacuum outlets than the original tank had. The additional vacuum outlets in the tank are now connected to hoses that are connected to nothing. I researched this discrepancy when I replaced the tank and thought it was fine. I'm obviously not completely clear what role these (and the carbs' ) vacuum lines are performing in the engine in general.
 

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Sitting on the bike, with stock tank, the left carb vacuum hose will go to the petcock. The right side goes to that air switching valve you have the picture of. On my bike, the nipple for that hose is on the right side as well.

I don't think it matters that in your case the hoses are reversed because if they are set correctly, they both will pull same amount of vacuum.

You might need to find a diagram for the 800 tank to see what the nipples are for. On the stock tank there are two on the front right bottom, a vapor vent, and a tank vent.
 

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Discussion Starter #4
After all this time, I have put the bike back together (cleaned the carbs, adjusted the valves, battled stripped coolant pipe bolt heads, encountered a coolant leak in the process). I was ready to run it, so first I switched the petcock to PRI to prime the carbs. As I was messing around the garage, I saw a huge gasoline puddle under the bike: so within 5 minutes on PRI, the gasoline leaked out of the carbs.

So my concern it 2 fold:

1. Should the gas be leaking out of the carbs if the bike is off and I'm in PRI setting on the petcock? If not, then I did something wrong with the carb reassembly after cleaning. But I'm near 100% sure I was careful to assemble the carbs back as I saw them when I opened them up (I didn't split them).
The leak seemed to come from the bottom half of carbs, as the top half of carbs was dry.

2. I am NOT sure that my carb hoses are all connected correctly.

- The opening post in this thread was to verify that the TOP FRONT L/R carb ports were correctly hooked up to Petcock Vacuum / Air switching valve respectively. So now those are connected correctly.

- Can anyone help verify the other two carb ports: REAR CENTER BOTTOM -> fuel line from petcock. REAR CENTER TOP -> not connected.
Is this right?

(Side note: my tank has two vents on right side on the bottom. Both of them go just connect to hoses which hang loose. Should any of the two vents connect to that opened carb port?)
 

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After all this time, I have put the bike back together (cleaned the carbs, adjusted the valves, battled stripped coolant pipe bolt heads, encountered a coolant leak in the process). I was ready to run it, so first I switched the petcock to PRI to prime the carbs. As I was messing around the garage, I saw a huge gasoline puddle under the bike: so within 5 minutes on PRI, the gasoline leaked out of the carbs.

So my concern it 2 fold:

1. Should the gas be leaking out of the carbs if the bike is off and I'm in PRI setting on the petcock? If not, then I did something wrong with the carb reassembly after cleaning. But I'm near 100% sure I was careful to assemble the carbs back as I saw them when I opened them up (I didn't split them).
The leak seemed to come from the bottom half of carbs, as the top half of carbs was dry.

2. I am NOT sure that my carb hoses are all connected correctly.

- The opening post in this thread was to verify that the TOP FRONT L/R carb ports were correctly hooked up to Petcock Vacuum / Air switching valve respectively. So now those are connected correctly.

- Can anyone help verify the other two carb ports: REAR CENTER BOTTOM -> fuel line from petcock. REAR CENTER TOP -> not connected.
Is this right?

(Side note: my tank has two vents on right side on the bottom. Both of them go just connect to hoses which hang loose. Should any of the two vents connect to that opened carb port?)
Hoses are correct......Shouldn't leak in "PRI" if you just turned it there to fill carbs....Sounds like floats or needles sticking.....You can try it in the "ON" position but I have a feeling you will need to take them apart again.
 

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The top, all black plastic "Tee" is the vent. It must be facing the rear of the bike or you'll get weird fueling issues. The bottom metal tube and plastic "Tee" nearest the left carb (has idle adjuster underneath) is the fuel rail.

 

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If it leaks with the petcock set to PRI, yes as Blaine mentioned, the needles are not seating, are dirty or stuck. I'm only posting the below because the common Haynes manual is garbage. The tool the instructions reference can be replaced with a clear, fuel safe plastic tube. Just mark a few mm lines on the tube with a fine Sharpie. This way you can check the bowl level with the carbs still on the bike.



 

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Discussion Starter #8
Thanks guys. I will repair the issue by rebuilding the carbs and checking the float level afterwards.

Sounds like its best to also install a very short hose from the top center port of the carbs and direct it backwards. I can't comprehend what the difference is between pointing it forward, down or backwards. Perhaps air pressure ... and that can affect carb functionality.
 

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Thanks guys. I will repair the issue by rebuilding the carbs and checking the float level afterwards.

Sounds like its best to also install a very short hose from the top center port of the carbs and direct it backwards. I can't comprehend what the difference is between pointing it forward, down or backwards. Perhaps air pressure ... and that can affect carb functionality.
The original hose comes out over the air box, and goes down next to the frame behind the left cover next to the fuse holder and such. I don't have a picture right now of that side, but I can try to snap one tomorrow.

Sent from my SM-N920V using Tapatalk
 

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My bike never had a hose. I point it back towards the rear of the bike on the theory that wind blowing past the tee facing up or down might generate a slight vacuum. Bernoulli...
 

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Discussion Starter #12
If it leaks with the petcock set to PRI, yes as Blaine mentioned, the needles are not seating, are dirty or stuck. I'm only posting the below because the common Haynes manual is garbage. The tool the instructions reference can be replaced with a clear, fuel safe plastic tube. Just mark a few mm lines on the tube with a fine Sharpie. This way you can check the bowl level with the carbs still on the bike.
I pulled the carbs and figured out the source of the leak. One of the carbs had a distorted bowl gasket. Though I bought them new from Kawasaki, the gaskets were just a bit longer than the gasket indentation in the carb bowl. Don't know why. Anyway, the gasket didn't sit correctly and thus the gas leaked out of the bowl.

I applied some lithium grease and sat the gaskets on both bowls down. Then attached the bowls again carefully. After connecting the fuel line and switching to PRI, no further leaks formed. Problem solved.

This is my second gasket leak during this major maintenance I sat out to do. I will remember to use grease on gaskets where safe, to keep them soft and compliant. An always replace gaskets if they look sh**ty.

I checked float levels by measuring travel distance before the needle is pushed in and compared to manual. It's within spec. I will save checking the true fluid level per Phreon, only if I can't get my carbs to run well.
 

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I pulled the carbs and figured out the source of the leak. One of the carbs had a distorted bowl gasket. Though I bought them new from Kawasaki, the gaskets were just a bit longer than the gasket indentation in the carb bowl. Don't know why. Anyway, the gasket didn't sit correctly and thus the gas leaked out of the bowl.

I applied some lithium grease and sat the gaskets on both bowls down. Then attached the bowls again carefully. After connecting the fuel line and switching to PRI, no further leaks formed. Problem solved.

This is my second gasket leak during this major maintenance I sat out to do. I will remember to use grease on gaskets where safe, to keep them soft and compliant. An always replace gaskets if they look sh**ty.

I checked float levels by measuring travel distance before the needle is pushed in and compared to manual. It's within spec. I will save checking the true fluid level per Phreon, only if I can't get my carbs to run well.
I've found that if any fuel hits those gaskets when you take them off they immediately swell and it takes hours for them to shrink back to normal size. Glad the gasket was the problem, and not something more serious! Good troubleshooting skills!

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Discussion Starter #14
After encountering engine issue with engine idling rough in idle and stalling on take-off I have performed carb clean and rebuild, valve adjustment, repaired a leaking coolant o-ring, repaired a leaking carb gasket. The initial problem I think was clogged up carbs due to fuel breakdown (I will now use fuel stabilizer Sta-bil in my tank).

I have started the engine and it ran just fine. The carb pilot screws used to be set on 3 turns out. I found that the engine idles all the same 1.75-3. It begins to stumble and RPMs drop-off at 1.5, and I haven't tried above 3. I left it at 2.5 to be safe. (- = leaner, + = rich for en500, right?).
 

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Remember, the pilot jet screw only controls mixture on idle and *just* coming off idle. The main jets control overall running mixture. If it's not stumbling at idle or coming off of it as you crack the throttle, you should be ok as long as you stay in the factory setting ballpark of 2 1/8 turns. It's usually better to be a little bit on the rich side than lean. Too rich fowls things. Too lean burns them.
 
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