Carb Sync Tutorial

[rickybobby]

As per my previous thread regarding my bike's problems:

http://cbr250.com/forum/thread-8178.html

I have decided to make a new thread featuring my effort in synching and balancing my carbs.

This is my first time doing this, and I encountered plenty of problems on the way. Hopefully, this tutorial can help those who also want DIY carb sync.

Lastly, I do not claim to be an expert on this, so if there are any wrong information, I hope you guys can chip in the correct info.


So here goes:


You will want to make yourself a carb sync tool (manometer). Instructions can be very easily found online, like this site where I based my manometer:

http://www.fz6-forum.com/forum/how-tos/3...-sync.html

Here is mine when done. I used ATF fluid by the way. Remember not to put too much fluid as to prevent being sucked in the engine in case your carbs are extremely unbalanced.




IMPORTANT


1. The first problem I encountered was that the clear hose does not fully seal against the plastic connector, leading to leaking fluid.

If fluid can leak out, air can definitely be sucked in when vacuum is applied during syncing.

So I applied some transparent epoxy sealant where the tubing joins the connectors to prevent any fluid leaks (cannot be seen in pic)




2. Second problem I had was that there were no vacuum adapters to be sourced locally, went to all the hardware, automotive, hydraulic stores and found none that had the 5mm thread needed for the cibby.

So I went online and got them here:

http://www.carbtune.co.uk/carbaccs.html

They ship fast, got them in a week's time.

I got the caps as well as I plan to leave the adapters on the bike permanently.

Picture below compares the adapter nozzles to the existing vacuum nozzle on the cibby (where petcock vacuum hose connects to)



Below, the adapters are screwed in (sorry for the dirty engine:-)):




3. Third problem I encountered was that during balancing, the engine gets hot enough to soften the vinyl tubes causing the vacuum to flatten the vinyl tubing. The readings go haywire when this happens.

So I got about 2 feet worth of black rubber hose (for car wiper fluid) for each cylinder, just so the clear vinyl tubing is nowhere near any hot engine part.




TIPS ON TUNING

This is by my experience during tuning, I am not sure if it would differ with your bike. If I have given wrong info please correct me.

1. Very small turns are needed to make changes in the balancing.

2. Even the pressure of the screw driver against the screw has an effect. So remove your screw driver when checking balance. Only put the screw driver when making adjustments.

3. Remember to warm up bike to normal operating temp before balancing.

4. Tuning procedure:

Screw 1 (between 1&2)
Clockwise = Fluid in hose 1 goes UP, fluid in hose 2 goes DOWN
Counter = Fluid in hose 1 goes DOWN, fluid in hose 2 goes UP

Screw 3 (between 3&4)
Clockwise = fluid in 3 goes DOWN, fluid in 4 goes UP
Counter = fluid in 3 goes UP, fluid in 4 goes DOWN

Screw 2 (middle)
Clockwise = 1,2 UP; 3,4 DOWN
Counter = 1,2 DOWN; 3,4 UP




Videos:

Before Syncing:





After Syncing:





It's still not as perfect as I want, but you can see there is a major improvement in the balance and engine sound as well.


That's all folks. I hope this will be of help to those who want to try to balance their bike DIY!

[Hellessey]

[Madman]

Nice dude... Except, considering the amount of time and effort you've put into that bike (epic build thread btw), clean the fucker will ya, lol!

[Aduro]

That is a solid effort. But I bought my vacuum guages for fifty bucks, they came with brass adaptor rods that screw into the vacuum ports and saved myself much hassle.

[Madman]

Aduro, where the hell did you get them for that price from!???

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Just saw these ones - http://www.ebay.com.au/itm/Motorcycle-Va...43a864a2c8

[aj26]

(02/02/2012 06:43)Madman Wrote:  Aduro, where the hell did you get them for that price from!???

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Just saw these ones - http://www.ebay.com.au/itm/Motorcycle-Va...43a864a2c8

Those ones were at MCA for $40 back in the day till they noticed they can get more money for them

[rickybobby]

@ Madman

The bike is dirty as I was having starting problems with it, so it was parked for about 2 months until I had the chance to fix her up. You cannot imagine how dusty it gets in my area, just a week and the dust builds up really quick!

She's gonna get a good scrubbing down this sunday.

[Madman]

haha, no need to justify yourself mate, I know and understand how you feel My bikes sit there hardly used and the amount of shit all over them in the sheds really does amaze me!

Question for you, how much did it cost you to build them yourself? Just curious!

[rickybobby]

The manometer?

Here's a quick breakdown:

Board = free
PVC hose = 0.45c
Black hose = $4.5
Adapters = $22
Fluid = free
Connectors = $1
Time = 1 day to make the manometer, 1 week waiting for the adapters

About $28 total, it would have been a whole lot cheaper if I could have gotten the adapters locally.

[Madman]

Nice and cheap!!

Im not sure I can really be bothered myself, id rather buy and save myself a day, even if it costs me an extra $50!