Date: 23-09-17  Time: 03:00 AM

Author Topic: How to Balance your carbs  (Read 17582 times)

Andrew

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How to Balance your carbs
« on: 03 January 2011, 07:08:23 PM »
Originally posted by pointer2null

The following instructions relate to a MK1 1998 Fazer, other models may be slightly different but the principle is the same.

 
 This is a guide, if you break it, burn it, scratch it, blow up your garage/bike/cat or do yourself any injury then that's your problem!
 
 Some of the tools needed:
  • Long Philips or pozidrive screw driver (to adjust the carbs)
  • 8mm socket (to remove the tank)
  • 10mm socket
  • 5mm Allen key (to remove the tank)
  • Security torx driver to fit the TPS
  • Pair of pliers (to remove the clips on the various pipes etc)
  • Small torch (not essential but damn useful)
  • Carb balancer (I'm using a Morgan)
  • Couple of rags

 The Morgan Carbtune - cost about £50 and well worth it.
 
 You can get them here www.carbtune.com
 
 First of all two notes on safety:
 
 You will need to disconnect and reconnect the fuel tank, petrol is highly flammable and the vapour is explosive in the right conditions. The vapour is heavier than air and can easily collect in an enclosed space. Do not smoke and be very careful to ventilate the area.
 
 You will need to run the engine during the procedure and exhaust fumes are highly toxic. Carbon Monoxide from exhaust fumes is a colourless odourless gas and breathing it will quickly lead to unconsciousness and death. Make sure you work in a well ventilated area or outside. If you are working in a garage you need to take special precautions to prevent a build up of toxic gasses
.
 
 I have an exhaust extraction system in my garage:
 
 
 
 Before starting this ensure that the tick over is set correctly, the air filter is clean, the spark plugs are clean and have the correct gap.
 
 Strictly speaking you should also check your valve clearances, but that is a big job. When I do it myself I will make another HOWTO and post it here.
 
 1) put the bike on it's centre stand and make sure it is stable and not going to fall over.
 2) Next we need to check the setting of the throttle position sensor (TPS)
 3) Switch on the ignition and disconnect the TPS plug, then reconnect it. This puts it into setup mode. The rev counter will now display 0RPM, 5000RPM or 10000 RPM.
 
 
 
 4) If it is showing 0 or 10000 loosen the two security torx screw slightly - just enough so that you can move the TPS housing, but no so much it moves on it's own.
 
 
 
 5) Twist the TPS housing so that the rev counter reads 5000
 6) Tighten the TPS torx screws taking care not to disturb the unit. Switch the ignition off.
 7) Remove the seat
 8)Using the 8mm socket remove the small bolt at the front of the tank just behind the handlebars.
 
 
 
 9) Using the 5mm Allen key loosen the Allen bold at the bottom of the tank.
 10) You can now partially lift the front of the tank, the rear bolt will act like a hinge.
 11) Underneath you will see 3 rubber pipes connected to the tank, a wire and the fuel tap. Two of the pipes are breather tubes and the other largest one is the fuel pipe. The wire is the fuel gauge sensor connection.
 
 
 
 12) Turn the fuel tap to the OFF position.
 13) Using the pliers remove the clips on the two small pipes - the breather tubes, then pull the tubes off the tank itself. Next the fuel pipe - it is a good idea to place a piece of rag under it as there is always a bit of fuel in the pipe that will run out.
 14) You can lift the tank a bit more and disconnect the fuel gauge wire.
 
 
 
 15) Lower the tank and completely remove the Allen bolt from the bottom. The tank can now be lifted off and put somewhere safe.
 16) Next you need to displace the bar that holds the coils and the fuel pump to allow you access to the carb adjustment screws. Remove the two 10mm bolts on either side of the bar and move it back as far as it will go.
 
 
 
 17) Replace the seat
 18) You can now place the tank on the seat back to front - this will allow you to reconnect the fuel line.
 
 
 
 Turn the fuel tap on.
 
 
 
 19) Remove the vacuum port covers on each of the carbs. Numbers two and three are tricky as there isn't much space.
 
 
 
 
 
 
 20) Connect your Carbtune or other vacuum gauge system to the vacuum ports. (If you only have a two way unit, just connect cylinders 1 & 2 first. Then you can repeat the process with 3 & 4 then finally 1 & 4 - remember to put the vacuum port covers on the cylinders you are not measuring!)
 
 
 
 You should now have the Carbtune connected, the fuel tank on the seat and connected all ready to go.
 
 21) Start the bike. Allow it to run for a few minutes to warm the engine. When it will tick over normally we are ready to start.
 
 The four carbs on the bike are linked via a shaft. This shaft has three adjustment screws on it. The one on the left side of the bike adjusts carb 1 relative to carb 2. The screw on the right hand side adjusts carb 3 relative to carb 4. The centre screw adjusts carbs 1 & 2 relative to 3 & 4.
 
 This is where the torch comes in handy - they are not easy to see (you'll find the right hand (as sat on the bike) screw the worst).
 
 Diagram as seen from front of bike
 
 
 
 
 
 
 This is an out of balance reading, yours maybe better or worse.
 
 
 
 
 22) Start by making a small adjustment to the left hand screw. After each small adjustment, remove the screwdriver and blip the throttle a few times. You will have to repeat this process a number of time until the vacuum on carbs 1 & 2 reads the same.
 23) When carbs 1 & 2 are balanced, repeat the process with carbs 3 & 4 using the right hand adjustment screw.
 24) When 3 & 4 are balanced use the centre screw to balance 1 & 2 with 3 & 4.
 
 Don't be surprised if you have to repeat steps 22 to 24 several times.
 
 When you are done the Carbtune should look like this.
 
 
 
 Tip: sometimes the carbtune can stick a bit - taping it will allow the indicator rods to settle.
 
 The maximum difference you are allowed is 10mmHG (about 2 1/2 lines on the Morgan, but you can get it much better than that).
 
 When you are happy with the balance, switch of the engine and the fuel tap.
 
 25) Disconnect the Carbtune and replace the vacuum port covers.
 26) Putting everything back is a reversal of the process you followed taking it all of.
 27) Repeat steps 3 to 6 to reset the TPS.
 
 Two things to REMEMBER TO DO:
 
 1) Turn the fuel tap on after refitting the fuel pipe
 2) Make sure the breather hoses are routed correctly and not crushed or kinked under the tank.

Video:
motorcycle carburetor balancing- Carbtune


« Last Edit: 03 January 2011, 07:09:38 PM by Andrew »

Fazerjon

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Re: How to Balance your carbs
« Reply #1 on: 24 December 2011, 08:03:50 PM »
Just balanced my carbs with the aid of your easy to follow steps. Runs like a dream now and its stopped the clutch clatter/ rattle on tickover too!  :lol

pointer2null

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Re: How to Balance your carbs
« Reply #2 on: 18 June 2012, 02:38:57 PM »
nice to see the piccies are back working again. Sort of looked daft with them missing.

JZS 600

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Re: How to Balance your carbs
« Reply #3 on: 18 June 2012, 06:43:02 PM »
After reading this, I feel like doing it myself!
 
After all, what could possibly go wrong,,,,,,,,
 
(I can do the routine stuff easy peasy but the fiddly stuff, I like to have the instructions as plain as possible)

DryRob

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Re: How to Balance your carbs
« Reply #4 on: 17 August 2012, 12:07:47 PM »
I did mine last night and you don't need to disconnect the fuel line, just unbolt the tank and turn it around carefully so you don't pull the pipe off.
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unfazed

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Re: How to Balance your carbs
« Reply #5 on: 11 December 2012, 01:20:28 AM »
A very good set of instructions, but the TPS adjustment should be completed after balancing the carbs.

a68war

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Re: How to Balance your carbs
« Reply #6 on: 22 December 2012, 06:33:45 AM »
Well done, very comprehensive instructions. I've ordered my Carbtune Pro and will give this a go as my tickover is a little uneven, my 1999 Fazer has done 33K miles, but other than that it starts and runs ok. I also have a 2008 Hayabusa and will check that as well sometime :)

Fazerjon

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Re: How to Balance your carbs
« Reply #7 on: 05 January 2013, 03:56:29 PM »
Well done, very comprehensive instructions. I've ordered my Carbtune Pro and will give this a go as my tickover is a little uneven, my 1999 Fazer has done 33K miles, but other than that it starts and runs ok. I also have a 2008 Hayabusa and will check that as well sometime :)
I thought a 2008 Hayabusa was fuel injected, not sure if you can use the carbtune on injected bikes. May be wrong though..... :rolleyes

Kentish

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Re: How to Balance your carbs
« Reply #8 on: 31 December 2013, 08:30:35 AM »
Touching TPS can be a fatal thing to do. I wouldn't touch it myself. My friend did on his bike and completely messed the fuel injection up. My understanding is that it's set at the factory and should never be touched,

Face9

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Re: How to Balance your carbs
« Reply #9 on: 23 May 2014, 12:25:44 PM »
Just did mine this morning, brilliant guide, wouldn't have attempted it otherwise  :D


Before / after:







« Last Edit: 23 May 2014, 12:27:12 PM by Face9 »

Dance the Kung Fu

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Re: How to Balance your carbs
« Reply #10 on: 17 June 2014, 12:52:41 PM »
Thanks for the guide, my bike feels much healthier at low revs now.

keratos

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Re: How to Balance your carbs
« Reply #11 on: 28 July 2014, 10:29:28 PM »
The Yam Shop Manual (section 3-11) mentions nothing about adjusting/checking the TPS whatsoever ?? I didnt do this and the balance is fine and runs perfectly in the sense of carbtune


pointer2null

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Re: How to Balance your carbs
« Reply #12 on: 30 July 2014, 02:59:37 PM »
When you balance the carbs you change the position of the flaps on carbs 1, 2 and 3 relative to 4 where the TPS is. So you can (depending on how much you adjust them) put the TPS out of adjustment. Hence the check.

keratos

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Re: How to Balance your carbs
« Reply #13 on: 30 July 2014, 05:23:47 PM »
When you balance the carbs you change the position of the flaps on carbs 1, 2 and 3 relative to 4 where the TPS is. So you can (depending on how much you adjust them) put the TPS out of adjustment. Hence the check.
ah, it should mention that in the manual surely? ah well. I see you're a C/C++ guy  (char *ptr = null;) !!

Spike1306

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Re: How to Balance your carbs
« Reply #14 on: 21 February 2016, 12:01:48 PM »
Hi

I know this is an old thread but I got linked to it.

I did the firsat part of getting the TPS to the right position, but when I did as the instructions the rev counter did absolutely nothing. Now the TPS is well lets say not in the same place it was when I started as i did not really pay attension to where it was.

What could cause the rev counter to not show a result and any way of setting it without the rev counter???

Apart from that great write up and my carbs are all balanced
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ReflexiveBeef

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Re: How to Balance your carbs
« Reply #15 on: 23 May 2016, 12:59:12 AM »
Hey if any of you chaps are still interested in the topic, can this job be done with the fuel tank in place, and with a short screwdriver (because I'm lazy like that)? Cheers!  :b  I am also a cheapskate in addition to being lazy so was thinking of making a set of carb manometers, courtesy of youtube. Anyone made their own? I just think that in a world of injected bikes, a carbtune won't be a worthwhile long-term investment really. Great tutorial BTW.
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mickvp

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Re: How to Balance your carbs
« Reply #16 on: 23 May 2016, 10:00:54 AM »
I doubt it could be done without at least tilting the tank upwards. And at that, it's only one extra bolt to be able to spin the tank around and strap it to the seat.

You would also need ridiculously small hands to get into the space with a short scrwdriver, so much easier with a long one.

sinto

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Re: How to Balance your carbs
« Reply #17 on: 23 May 2016, 11:24:04 PM »
I doubt it could be done without at least tilting the tank upwards. And at that, it's only one extra bolt to be able to spin the tank around and strap it to the seat.

You would also need ridiculously small hands to get into the space with a short scrwdriver, so much easier with a long one.
I've always found it easier to get someone else to do it and it only cost a bottle or two of Scotlands finest eh Mick?  :thumbup
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mickvp

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Re: How to Balance your carbs
« Reply #18 on: 24 May 2016, 11:21:45 AM »
Aye wel that does help too mate.

Valid point actually, why bother even "making" a set of carb tunes, why not just post your location like Colin above did and see if there is a foccer nearby who can pop round with theirs one day.

sinto

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Re: How to Balance your carbs
« Reply #19 on: 24 May 2016, 11:42:51 AM »
Aye wel that does help too mate.

Valid point actually, why bother even "making" a set of carb tunes, why not just post your location like Colin above did and see if there is a foccer nearby who can pop round with theirs one day.
:agree

And then you'll hopefully get a nice chap who'd come and help you out :)

Don't ya just love foccer bromance :rollin
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