Carb balance between front and rears different

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Blobber
Posts: 186
Joined: Mon Jan 07, 2008 5:34 am
Location: Lancashire, England

Carb balance between front and rears different

#1 Post by Blobber » Mon Jul 03, 2017 6:23 am

Hi, I have just finished using a set of vacuum gauges on my modded carbs (added barbs on the each carb) to check the balance and found they just needed minor tweaks to make the 2 rears spot on with each other and the 2 fronts the same. The funny thing is the two rear cylinders pull a lower vacuum than the 2 fronts. If you attempt to equal the front and rears by opening up the adjuster screws on the rear carbs they go off the adjusting range (springs no longer compressed by the adjuster screw). It is also visibly obvious that as you try and increase the vacuum on the rears the rear carb slides are opening up well before the front and that is clearly not right.

The bike runs brilliant and I've just accepted that the vacuum difference must just be part of the design. Just wanted to see what theories other have about why this is the case. Is it something to do with the different induction systems used on the front and rears? Or is there something wrong with my bike, but as I say it runs fantastic.

thanks
Trevor
Bikes:
RZV500R FZR1000 forks wheels JL pipes
RD350LC N2

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