Carb Balancing

Discussion in 'Technical Help' started by Simon Logan, Nov 23, 2020.

  1. Simon Logan

    Simon Logan Active Member

    Jun 13, 2020
    138
    33
    Sutton Coldfield - UK
    • Thanks Thanks x 1
  2. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,358
    800
    Nr Biggar
    Not too readily! You need a 4 cylinder version and block one tube. For all the frequency you’ll do this make a simple manometer yourself with fish tank tubing and plastic bottles for less than a fiver. Use a lightweight coloured oil or ATF for a stable signal. Google it!


     
    • Like Like x 2
    • Useful Useful x 2
    • Agree Agree x 1
  3. joe mc donald

    Subscriber

    Dec 26, 2014
    14,438
    1,000
    slough / burnham
    Simon Logan
    Simple answer no you can't.
    Joe
     
    • Agree Agree x 1
  4. Simon Logan

    Simon Logan Active Member

    Jun 13, 2020
    138
    33
    Sutton Coldfield - UK
    Hi Joe, the reason I asked is becuase I've never done it before. I kind of understand what is going on .These guys are using a two gauge carb blancer ? Using the middle carb as the reference then they use second gauge for the left and then the right carb ?....or am I missing something ?

     
    • Like Like x 1
  5. Ducatitotriumph

    Ducatitotriumph Crème de la Crème

    Apr 25, 2019
    2,181
    1,000
    Rothwell
    You can use a 2 on a 4 but not sure about a 2 on a 3 I’m afraid!
     
    • Agree Agree x 1
  6. MadMrB

    MadMrB Elite Member

    Dec 24, 2018
    3,562
    800
    Northamptonshire, UK
    I have seen a video (on YouTube) on how to do this, but can't find it at the moment. If I remember correctly you establish what is your master (reference) carb, which you do not adjust, then in turn sync the other two carbs to the master carb.
     
    • Agree Agree x 3
  7. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,358
    800
    Nr Biggar
    .....hence my ‘not too readily’. You are basically switching the whole time to create a common ‘datum’ (the master carb) that is itself initially a moveable feast you have to first find in increments. It’s doable if you already know what you are doing but all the ‘professional’ devices really offer speed + convenience. They are little more accurate than a well made lash up. As I said, the key is to use something runnier than 20/50 but less bouncy to the vacuum signal than water.
     
    • Useful Useful x 1
    • Agree Agree x 1
  8. joe mc donald

    Subscriber

    Dec 26, 2014
    14,438
    1,000
    slough / burnham
    Simon Logan
    Yes I understand mate. The difference is you are watching a professional doing a job he could do with his eyes closed. But if you are just having a go it could cause you so many problems it would be better to get them set up by a professional. But if you feel confident do give it a go. You always find the lead carb usually no 2 then work from that but check over as when you adjust one carb it will offset the other so check check check.
    Joe.
     
    • Like Like x 2
  9. Simon Logan

    Simon Logan Active Member

    Jun 13, 2020
    138
    33
    Sutton Coldfield - UK
    Hi Joe, took your advice and went for the Carbtune 4 col :) Thanks for the comments everyone
     
    • Like Like x 1
  10. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
    2,441
    1,000
    Norfolk UK
    • Like Like x 1
  11. Simon Logan

    Simon Logan Active Member

    Jun 13, 2020
    138
    33
    Sutton Coldfield - UK
    Does anyone know what number of turns out the mixture screws are set to when they come out of the factory ? My carbs were 1 3/4 turn out but I'm sure I read somewhere it should be 2 1/2?
     
  12. Simon Logan

    Simon Logan Active Member

    Jun 13, 2020
    138
    33
    Sutton Coldfield - UK
    Hi Joe, I assume the nunbers don't really matter so long as they are all the same on each gauge ?

    IMG_3022.JPG
     
    • Like Like x 2
  13. Rocker

    Rocker Elite Member

    May 1, 2016
    1,662
    800
    Suffolk
    Correct
     
    • Like Like x 1
  14. capt

    capt Elite Member

    May 8, 2016
    3,051
    750
    western Australia
    The higher the numbers , the greater the vacuum ! Higher vacuum reading = healthier motor ! Shows how good seal on rings and valves are !!!

    Fluctuations in vacuum can be highly indicative of valve seats or spring condition on cylinder that 'bounces' at higher rpms of course.
     
    • Like Like x 1
  15. Simon Logan

    Simon Logan Active Member

    Jun 13, 2020
    138
    33
    Sutton Coldfield - UK
    Hi, I didn’t know that. Do the readings look ok? I had the valves checked and adjusted along with a compression check which was also good. I know nothing about carbs so was really happy that I managed to strip,clean and replace all the parts and it still runs !! There was brown gunge leaking from somewhere underneath the carbs which has also stopped. The O rings in the mixture screws for 1 and 3 had perished which is where I think the gunge was coming from. I’m an expert in getting the carbs out now....30 mins
     
    • Like Like x 1
  16. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
    2,441
    1,000
    Norfolk UK
  17. t552

    t552 Senior Member

    Nov 17, 2014
    417
    113
    Bristol UK
    In the vid he should have gone back to 1 and 2 again I'll guarantee they would be slightly out again.
     
    • Useful Useful x 1
  18. capt

    capt Elite Member

    May 8, 2016
    3,051
    750
    western Australia
    All 3x are almost = and we'll within specified normal range.
    There was a chart that gave likely caused for various vacuum readings and when vacuum fluctuations were in evidence , what different ranges of fluctuation levels were caused by.
    I think I'll look through my course work/notes see if I have a copy
     
    • Like Like x 1
  19. TheDigiSync

    TheDigiSync New Member

    Jan 4, 2024
    0
    1
    USA
    I know this is an old post, but thought I'd chime-in.

    Many folks aren't aware that periodic Throttle Body Synchronization (Carburetor Synchronization for the older machines) is part of routine maintenance.

    From time and abuse, even cables and linkages can wear and stretch. This results in throttle plates opening at slightly different times from one another. This slight difference has a significant impact on your bike's throttle response. Have you noticed that the bike you bought brand new is now a bit slower at the green lights than when you bought it? You're not imagining that. It's likely because your throttle isn't as responsive as it once was. And, this same issue is also robbing you of your gas mileage.

    This is why periodic Throttle Synchronization is recommended. Now, if you're into racing or stunt riding, that crisp throttle response quickly becomes a safety issue as well!

    It is recommended to perform a Throttle Body Sync at the following times:

    -Periodic maintenance

    -After buying a used bike

    -Whenever your machine bogs down, or throttle response is no longer crisp

    -When racing or stunt riding because in these sports, throttle response is a safety issue.

    -After valve service

    -After servicing carburetors or throttle bodies

    -After cleaning the fuel system

    There are a variety of options out there for Throttle Synchronization. I'll quickly give you a run-down:
    1.) Ignore it and live with the loss of performance and gas mileage.
    2.) Tune it by using only the sound your ears hear. The only mechanics I know that can pull this off successfully have +20 years of experience.
    3.) Mechanical Dial/Needle Gauges. These require troublesome calibration, and the needles bounce all over the place, leaving you wondering just how accurate your Synchronization really is.
    4.) Manometer Fluid gauges. These fluids evaporate and need to be replaced from time to time. Plus, there's the risk you rev your engine too high and suck the fluids in, causing engine damage!
    5.) Professional Digital Carb Sync Tools. These are the easiest to use because they automatically calibrate and give you trustable accuracy that exceeds your manufacturer's specs. However, these come with a "Pro" price tag ranging from $500-$2,000!

    Wouldn't it be great if you could get a Professional Digital Tool for this task without spending a ton more than the Mechanical or Fluid gauges?

    That's exactly why we created www.TheDigiSync.com. We're not business people. We're just engineers who also love wrenching on our own bikes. We, like you, want the best tools, without paying outrageous prices. So, we created this tool for ourselves and shared it with our friends at local bike meetups. That was in 2015, and the response was so amazing that we decided to spend the next 8 years perfecting this thing into what it is today.

    The Digi Sync is quickly becoming "the tool" that motorcycle repair shops love and trust for Throttle Synchronization.

    Need more proof? The Bearded Mechanic (215K YouTube Subscribers) says that after he got his Digi Sync, his old needle gauges became "Wall art".

    We've worked hard to get our starting price down to just $145.95 so that this isn't a Mechanic's only tool. It's intended to be a tool any DIYer can use. If you can figure out how to change your own oil, you can do a Throttle Sync job. We've had many customers tell us that The Digi Sync made the task so easy they were done in 15 minutes!

    While supplies last, use Promo Code "GoFast24" for $10 off.
     
Loading...

Share This Page