How to balance your carbs

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AMCQ46
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How to balance your carbs

Post by AMCQ46 »

A simple "how to" balance the carbs on the VTR. -

if you need to print off there is a PDF version here pdf link

1st thing you need to do is fit a vacuum adapter to the front cylinder intake. There is one already fitted to the rear which is used to operate the fuel tap, but the front take-off point is blanked off with a 5mm Allen head screw.
You will need to purchase a 5mm threaded brass adaptor if you want to permanently fit the adaptor, or you can use a plastic adapter which probably came with your balance gauge, but if you do this you will have to refit the blanking screw after you do the balancing.

Brass screws from Carbtune http://www.carbtune.co.uk/carbaccs.html, but you get a pack of 4, when you only want 1! perhaps if you call them up they will sell you a single. I suggest you also get a length of vacuum hose from them at the same time.

To fit the screw you have to get the tank off and the airbox, hence it is a lot less hassle to fit the brass one and then you can do any future checks without disturbing the airbox.
If you are going to leave the adapter fitted then they recommend that you remove the o-ring, and use a thread lock sealant. Also dont over tighten, brass is not a strong as steel.

first photo shows the location of the front vacuum take off point.
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Then you will need to fit hose to the front cylinder and put a T piece in the rear hose [as as you will need to keep vacuum to the fuel tap to run the engine], the T piece can be bought at Halfords for £1.50, you will find them in the same section as the nuts, bolts and electrical connectors.
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As you have the airbox off to fit the adapter, and it is easier to get to the adjuster screw, the first time you balance the carbs it will be easier to do it with the airbox off.

You need to get the petrol tank back on to get the bike started, but you cant fit it in the normal place or you cant reach the adjuster screw. I fit the tank backwards with the hoses on the opposite sides.
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At this point you need to fit your balance gauges, these come in many shapes and methods from individual clock gauges, oil manometers or in my case a ball bearing comparator. As it is only 2 cylinders this one is fool proof, it has no calibration errors and is unbreakable :thumbup: the lower ball has the vacuum from each cylinder acting on each side, the upper ball is only for reference showing where zero should be.
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Get the engine warm and then lift the idle speed slightly to a point where your gauges are giving a stable reading. if there is any difference between the readings from each cylinder [or in my case if the moving ball is to either side of the reference ball, then you adjust this screw.
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which direction will depend on which cyl is high and which is low. your reading will change so you can work out if you are going the correct way or not.
After each adjustment, blip the throttle slightly and let it settle to the fast idle.

Now you have got your carbs balanced the first time, you will not need to take the airbox off next time. The adjuster can be accessed [just] with the airbox in place.
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And if you route the 2 open ends of the vac pipes [new one from the front and one from the t-piece in the rear] to a suitable position where you can access them with the tank on you can now periodically check the balance without removing the tank...........clearly if you need to make any adjustment the tank has to come off, but this makes the checking easy.

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last job is to blank off the open ends of the 2 vac pipes. I used the plain section of a long M5 Bolt, but I am told Golf tee's are a great alternative...........It is important that you dont have air leaks here so dont try and seal on the treaded section of a screw.

I then tuck these pipes up with the thermstat housing between the V so they cant be seen.

Job done.. go have a cup of tea to congratulate yourself! :beer




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Last edited by AMCQ46 on Sun Jan 07, 2018 7:51 pm, edited 5 times in total.
AMcQ
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sirch345
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Re: How to balance your carbs

Post by sirch345 »

Nice job AMcQ with good quality photo's too :thumbup: Well done mate :clap:

The same type of balancer I use myself.

Chris.
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SWAGGER
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Re: How to balance your carbs

Post by SWAGGER »

AMCQ46 wrote:first photo shows the location of the front vacuum take off point.
Image
See that black plastic shroud protecting the carb (I think that's what it's function is) is it supposed to have a hole in it? Mine has .... only just noticed it. Looks like someone has done a half arsed mod in order to access something.
The force is strong with this one!!!

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benny hedges
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Re: How to balance your carbs

Post by benny hedges »

yes the hole is for access to the intake rubber clips
i thought ecactly the same first time i saw it!

you get a more stable / accurate reading if you restrict the vac pipes a bit.
if you havent got restrictor valves with your gauge kit, use a clothes peg on the rubber hose.
turning the screw only alters the balance of the rear cylinder against the front, as the front is not adjustable.
give the bike a good revving between adjustments and let the idle settle down again.
if you do turn the tank back on itself and place it on the seat, be sure to turn it back the same way when you put it back or you will put a twist in the fuel pipes! :oops:
also watch it doesnt vibrate off the subframe when you rev the bike!

i find i can get at the adjuster screw easy enough just by undoing the 2 tank bolts at the front and prop the tank up with something.
it's also easier to make accurate adjustments with an 8mm socket on an extension bar rather than a x head screwdriver, as the screwdriver pushes the actuator cam as you turn it and gives a false reading.
it's one of them things that gets easier the more you do it!

cheers for the guide ali, i cba doing one lol and mine is in bits anyway!! :beer:
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SWAGGER
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Re: How to balance your carbs

Post by SWAGGER »

benny hedges wrote: ... yes the hole is for access to the intake rubber clips ..... i thought ecactly the same first time i saw it! ....
:D Good thought I was gonna have to rectify somefink else. :roll:
The force is strong with this one!!!

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Re: How to balance your carbs

Post by Twinpotter »

Cool :clap:
I use the carbtune to, good kit. :thumbup:
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Re: How to balance your carbs

Post by steveb »

Carb balancing is way beyond my technical ability -

'edit' Having re-read AMcQ's post I think this may be within my abilities. Which leads to me adding another Q below;

How often does it need doing?

Does Halford sell the balancing gauge you used here AMcQ?

How much does a bike shop charge do to the job?
Happy ridin'
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benny hedges
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Re: How to balance your carbs

Post by benny hedges »

m8, it's really easy to do.

the hardest thing is getting the adaptor in under the front carb, just a bit fiddly.
the rest is a doddle.
keep a sharp eye out for one of tony's workshop days!!!

have a look on ebay for vacuum gauges - theres a twin set (round gauges on a blue plate with all the pipes and fittings) for about £20 - thats what i got and it's been great so far.

as with anything else, a shop will charge you a fortune.
thing is, it's a check, and adjust if necessary.
a shop will charge you an arm & a leg and it might not even need adjusting.
You do not have to say anything. But it may harm your defence if you do not mention when posting something which you later rely on in quote. Anything you do say may be ripped to sh*t.
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AMCQ46
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Re: How to balance your carbs

Post by AMCQ46 »

steveb wrote:
How often does it need doing?

Does Halford sell the balancing gauge you used here AMcQ?
Halfords dont sell carb balance kits, but tehre are all types on e-bay if you search using those words

I have to admit I bought the ball balancer off a bloke who sells on e-bay, I should have tried to make one, but was too lazy.
http://cgi.ebay.co.uk/UNIVERSAL-MOTORCY ... 4cf459c124

As benny said, it is a check, only need to adjust if they are out of sync, after 18,000 miles mine were only very, very slightly out [i think a shop would not have bothered adjusting, but I am a perfectionist], so dont expect that you have do it often or that you will need adjustment if you do check it.
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steveb
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Re: How to balance your carbs

Post by steveb »

AMcQ, Benny,

Thanks for you advice, 'how to' and links - I'll have a go at this.

Cheers

Steve
Happy ridin'
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tony.mon
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Re: How to balance your carbs

Post by tony.mon »

AMCQ46 wrote:
after 18,000 miles mine were only very, very slightly out [i think a shop would not have bothered adjusting, but I am a perfectionist]
But when you've got that far you might as well, you've done 99% of the job.
It's not falling off, it's an upgrade opportunity.
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Re: How to balance your carbs

Post by geodude »

I stuck this in a PDF for those that need to print it off :)

How to balance your carbs - VTR1000F
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AMCQ46
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Re: How to balance your carbs

Post by AMCQ46 »

Thanks George, you are now my publisher :thumbup: :lol:
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Re: How to balance your carbs

Post by geodude »

Hehe. Thanks. The invoice is in the post. :cool2
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Re: How to balance your carbs

Post by Wicky »

https://www.davidsilverspares.co.uk/par ... 214MB0000/

Brass screw-in vacuum hose connector for the front cylinder / Boost joint part no. 16214-MB0-000 £2.50

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Last edited by Wicky on Tue Feb 16, 2021 10:19 pm, edited 2 times in total.
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