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Discussion Starter #1
For some strange reason I am still experiencing engine hanging, even though I have tried to adjust the air/fuel mix on the carbs. After adjusting them almost all the way out it still does it. So my question is if I adjust the carb sync screw would that help? If so, since I have not done that particular procedure before, can anyone show me pics of how to do that? I have seen and read the post's on it and even seen the instructions on how to make the $1.55 manometer but I still have no idea of how it works. I have read the manual and do understand that it controls the vacume to the rear cylinder, one way riases it and the other lowers it. I do know they are out of sync since a DUMB friend of mine thought it was the idle and he turned it before I could stop him and show him where it was really at. Now I want to correct that. Sorry, call it a brain fart or a learning curve of some sort but I still can't figure it out or understand the manometer part. I need HELP baddly. Someone? Please! :notworthy
 

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I'll see if I can take some pics this evening and post 'em - it's pretty straightforward once you've hooked the tubes to the vacuum ports.
 

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Discussion Starter #3
Thanks Cindy I just for some reason can't understand the manometer thing and don't worry I won't do the do dooo thing and get that started again LOL. :) I'm sure if I can see what to do that would help me greatly. That and see how that thing is made too.
 

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Old Truck Junkie
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I tried using this set up, the clear tube with auto-trans fluid in it, and all I managed to do was run the oil into the carb and out the muffler. The tube may have been too small inside diameter.
 

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85 VN 700
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I built a VERY cheap and simple version of the manometer. My only cost was the tubing. A scrap 2X4, some holes, the vacuum hose that the PO had on the bike when I bought it, and some oil. I would recommend using a lighter weight oil than I did (I think I used 15/40) - I had to let the system sit for a couple days after putting it together to let all the air bubbles settle.

Here's some pics of the carb parts and the ******* manometer. I tried to indicate carb parts with the end of a pen. Excuse the crappy picture quality.


Right hand vacuum port. Tried to point to it with the pen - it's the black hose piece.


Left hand vacuum port.


Carb sync screw. It's the yellow thing. As viewed from the left hand side.


You can't see the screw here, but the pen is pointing to it. Attempting to give a better idea of where it is.


my ******* manometer


Manometer ends. Just slipped the vacuum lines over the hose... works for me!

Refer to clymers as to which way makes the vacuum go which way. Seems like you need a 7 or 8 mm mini wrench (clymers will tell ya).
 

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Discussion Starter #6
The vac ports have the black and red hose on it right? Just above the air/fuel mix screws? The sync screw takes a 7mm wrench and I still have my old honda tool kit so I have the wrench. How far up do I fill the tubes on the manometer with oil about half way before I let it set for a bit? Thanks Curtis for the pics. ;-)
 

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The vacuum port on the front carb should be connected to your petcock so fuel will flow to the carbs once the engine starts. For the carb sync you will need to find an alternate vacuum source so your bike will stay running while you have the monometer hooked up.
The rear vacuum port is hooked to the EGR system and that can be removed and plugged temporarily while the manometer is hooked up.
Both vacuum ports are already connected to something so it is just a matter of disconnecting the hoses and then reconnecting once you are finished.
For the oil not to be sucked up into the carbs, both vacuum ports have to be connected to the manometer at the same time. You adjust the sync screw until both sides of the manometer are of equal height. You will probably have to shut down the engine in order to reach the screw to make the adjustment and then restart. Hence the need for an alternate vacuum source so you don't run the carbs dry. I use a hypodermic syringe hooked to the line with the plunger pulled out to create enough vacuum for the petcock to stay open.
 

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Discussion Starter #8
What about the Prime setting that needs no vacume? Mine don't have the off setting and the Prime just lets the fuel fall into the carbs freely so would that allow me to use it instead?
 

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Yes, prime would work to keep the carbs fueled up while you do the sync.
 

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Discussion Starter #10
COOL!!! That would be alot easier that way
 

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85 VN 700
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Yup. The black and red line is the vacuum line. The vac line on the left side carb should be connected to the middle port on the petcock.

Prime works fine (that's why I didn't mention it... I have an 85 and didn't think about it)., and yes you do need to have the manometer hooked to BOTH sides or you will suck oil through the carbs.
 
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