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I had the carburetors off the project bike tonight and decided to take some pics of the idle adjust and carb sync screws. Also tried to demonstrate how to visually sync the carbs before putting them on the bike, but couldn't quite manage to do that. So I tried to offer descriptions for each picture about the steps to take while synchronizing. I can add pics when I hook up the manometer, if anyone would find that helpful. But hopefully these will help folks visualize what's going on - or needs to go on - when the carburetors are being synchronized. Let me know if I missed anything or if you have questions that maybe I should address in this album.

http://www.vn750.com/photopost/showgallery.php?cat=655&ppuser=962
 

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sweet! I feel stupid...
I am guessing syncing is done with the carbs on the bike? so....
so I just set the idle adjust knob to around 1100 rpms, then adjust the carb sync screw until the vacuum is equal? now to figure out how to measure the vacuum/ get it equal...lol... that's where the feeling stupid part comes into play...
 

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I know that there are some posting on here how to do it. just a matter of looking. I learned how to sync carbs off this site here. twins are pretty much all the same, just easier then 4's.http://faq.ninja250.org/wiki/How_do_I_synchronize_the_carburetors? the apparatus they make here is pretty cool and does the job very well. The only thing they forget it that with our bike you need a 't' for the hoses, but the instructional matter on our site covers that.
 

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I know that there are some posting on here how to do it. just a matter of looking. I learned how to sync carbs off this site here. twins are pretty much all the same, just easier then 4's.http://faq.ninja250.org/wiki/How_do_I_synchronize_the_carburetors? the apparatus they make here is pretty cool and does the job very well. The only thing they forget it that with our bike you need a 't' for the hoses, but the instructional matter on our site covers that.
Jace, if i remember correctly, the T is to supply vacumn to the petcock so that fuel will flow, correct? If you have a vacumn pump or a medium sized syringe, you can create vacumn for the petcock without a T.
 
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Jace, if i remember correctly, the T is to supply vacumn to the petcock so that fuel will flow, correct? If you have a vacumn pump or a medium sized syringe, you can create vacumn for the petcock without a T.
THat's right. I'll take some pics of my homemade manometer and add 'em to the album. I guess that part is often just as confusing as which screw to turn and when.
 

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Cindy -

Great idea, seeing those screws and understanding which way does what is really difficult when mounted on the bike in the abyss between the cylinders.

Jon
 
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Jace, if i remember correctly, the T is to supply vacumn to the petcock so that fuel will flow, correct? If you have a vacumn pump or a medium sized syringe, you can create vacumn for the petcock without a T.
Yes, the "T" is for the fuel flow. From my experience, you need the bike running long enough to be at operating temp, then have to shut it and start it several times while making the adjustment. I think the "T" is the only way to go.

Jon
 

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sweet! I feel stupid...
I am guessing syncing is done with the carbs on the bike? so....
so I just set the idle adjust knob to around 1100 rpms, then adjust the carb sync screw until the vacuum is equal? now to figure out how to measure the vacuum/ get it equal...lol... that's where the feeling stupid part comes into play...
I used a yard stick with clear tubing on it. The bottom of the yard stick has the bottom of the "U" you make in the tube with the two ends going up the stick. Pour some 2 cycle oil into the tube so that you get perhaps half way up the yardstick on both sides.

Then connect the ends of the tubes to the two vacuum ports on the carbs. (splicing in the "T" on the left side).

When you start the engine, the carb with more vacuum will pull the 2 cycle oil up that sides tube. The secret is to make VERY small adjustments to the balance screw until the two sides are level in 2 cycle oil height.

Remember you are balancing the carbs, not setting a vacuum amount.

Speaking of a picture being worth a 1000 words.....http://zoic.org/sharkey/moto/r100gs/redneck.html

Jon
 
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Cindy -

Great idea, seeing those screws and understanding which way does what is really difficult when mounted on the bike in the abyss between the cylinders.

Jon
+1

I used a yard stick with clear tubing on it. The bottom of the yard stick has the bottom of the "U" you make in the tube with the two ends going up the stick. Pour some 2 cycle oil into the tube so that you get perhaps half way up the yardstick on both sides.

Then connect the ends of the tubes to the two vacuum ports on the carbs. (splicing in the "T" on the left side).

When you start the engine, the carb with more vacuum will pull the 2 cycle oil up that sides tube. The secret is to make VERY small adjustments to the balance screw until the two sides are level in 2 cycle oil height.

Remeber you are balancing the carbs, not setting a vacuum amount.

Jon
+1 & good info.
 

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Thanks for the info...this can be confusing the first time you do a sync.

I used an older 4 channel Motion-Pro mercury sync, only because I had access to a friend's...otherwise I would probably be trying the tube design.

I had the bike revved pretty high and let go of the throttle many times, but never came close to sucking in the mercury, because the lines are very tall compared to where my carbs were on the scale and there are reducers (not sure if that's the technical term) in the lines near the carb inlet side of the lines.
 
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