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/39891-build-your-own-manometer-throttle-body-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.
![Image]()
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)
![Image]()
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)
![Image]()
Below, the adapters are screwed in (sorry for the dirty engine
):
![Image]()
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.
![Image]()
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
![Image]()
Videos:
Before Syncing:
http://youtu.be/a1sNxTUXiEM
After Syncing:
http://www.youtube.com/watch?v=pvN_W_ySP1Y&feature=youtu.be
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!
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/39891-build-your-own-manometer-throttle-body-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:
http://youtu.be/a1sNxTUXiEM
After Syncing:
http://www.youtube.com/watch?v=pvN_W_ySP1Y&feature=youtu.be
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!
