Date: 19-11-17  Time: 21:48 PM

Author Topic: Last job is to balance the carbs, and I can't seem to get it right  (Read 830 times)

daviee

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #25 on: 11 November 2017, 02:49:54 PM »
if you no so much about suck and blow you would realise inlet side only sucks thats how it creates a vacuum and if you no  so much about cheep vacuum guages then you will realise im right as you set them on a carb not to zero just off the stop needle that is not where you need them to be accurate you need them to be accurate at the vacuum reading the carb gives but of course being a motorbike mechanic and rolling road operator means nothing to balancing carbs you need to no about aircraft's to do that  :z

Disorderlypunk

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #26 on: 13 November 2017, 09:13:05 AM »
ok this is getting out of hand very quickly


so setting them all at the same zero would work in a perfect world and most of the time could work
HOWEVER
due to how these sort of things work they need calibrated in use as they have moving parts and springs and all other things that may not be exactly the same as each other and will show a different reading anywhere other than 1 bar


another way to explain  calbration is  2 torque wrench's sitting on a table, one calibrated, one way out
you have no way to know which is which untill you put them under force on a test rig
ok we dont have a test rig for vacuum BUT WE DO we have four different ones of them
each cylinder is its own test rig giving the same vacuum all the time (ish)

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Jamieg285

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #27 on: 13 November 2017, 02:01:24 PM »
Surely the calibration technique depends on what or how you are trying to measure?

If you are measuring actual values of vacuum, then it's important to get them zeroed properly.

If however you're just trying to balance them, it doesn't matter whether the needle starts at 0 or 100, what's important is that all the guages read the same value for the same level of vacuum.

Therefore, in this argument, I side with Daviee.

Disorderlypunk

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #28 on: 13 November 2017, 02:19:08 PM »
now is the time to take the piss
its time for a poll


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BBROWN1664

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #29 on: 13 November 2017, 02:27:52 PM »

Surely the calibration technique depends on what or how you are trying to measure?

If you are measuring actual values of vacuum, then it's important to get them zeroed properly.

If however you're just trying to balance them, it doesn't matter whether the needle starts at 0 or 100, what's important is that all the guages read the same value for the same level of vacuum.

Therefore, in this argument, I side with Daviee.


This is what I have been saying.


You set the gauges to all read the same to start with. DO NOT use the stop needle, set the gauges a fraction off it if you have one as that way you know all the gauge as are starting at the same point. Atmospheric pressure will try to move the gauge above or below zero so you set it every time you use it.


following that, chances are your gauges are not accurate anyway and have not been professionally calibrated so you are just looking to see that you have the same reading on all four cylinders.
« Last Edit: 13 November 2017, 02:31:37 PM by BBROWN1664 »
Another ex-Fazer rider that is a foccer again

daviee

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #30 on: 13 November 2017, 05:52:37 PM »
if you are wanting to measure the actual vacuum them cheep analogue gauges like the ones pictures  are deffo not the way to do it the will get your carbs close if you calibrate them as  i have said but the best is deffo mercury gauges ,

Hugh Mungus

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #31 on: 13 November 2017, 07:37:33 PM »
If you're wanting to save money by doing the carb balance yourself then buy mercury gauges. They may be more expensive than the other gauges but you're already saving on labour costs at a workshop. So buy some good one's and look after them.


If you've got the cheaper dial gauges you do need to sync them together by using one carb as a bench setting for all four gauges. It is the most accurate way you're going to get a proper reading. Even with mercury gauges it is advisable to do the same to double check that each gauge is giving the same reading as it can point to leaks in the tubes etc.
Pat.

darrsi

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #32 on: 14 November 2017, 06:48:55 AM »
Think i paid around 50 odd quid for my Morgan Carbtune gauges, in used but virtually mint condition.
After the second time of use you've technically saved money through labour costs if you were paying a mechanic, plus after the fifth time of using it you actually get a bit handy at using it, plus your learning curve increases even if it can be a slightly frustrating process with adjustment screws in hard to see daft places and twice now i've kinked my fuel tank pipe so it's run out of fuel mid process.
A very worthwhile and satisfying job once done though, the bike runs really sweet afterwards, as long as your air filter, TPS, and bike in general is in reasonably good order whilst it's being adjusted.  :)
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Hugh Mungus

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #33 on: 14 November 2017, 12:25:06 PM »
It can turn a dog of a bike into a really sweet ride. Always worth doing.
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redmandan

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #34 on: 14 November 2017, 02:12:28 PM »
OK guys, if I can ask some advice again. I've been having another go and I'm stumped again. Made a vid to show my problems:

To re-iterate the video: I have the carbs balanced about as well as I can hope/get with the vaccuum gauges I have. The idle screw is now basically redundant. The only way I can change the idle speed is by turning the centre carb balancing screw, just a quarter of a turn changes about 1000 revs and doesn't affect the balance at all. Am I doing something wrong here? Shall I just put it back together and forget about it?


Thanks for any help

unfazed

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #35 on: 14 November 2017, 04:54:37 PM »
Bet your sorry you asked the first question :lol :lol :lol

Most likely the throttle cables are adjusted incorrectly

Check the adjuster at the handlebar side is backed off fully and if it is loosen the cables at the carburettor end

His Dudeness

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #36 on: 14 November 2017, 05:48:47 PM »
Ohh the joys of bikes :lol Sounds like it's running on three cylinders when it's idling

daviee

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #37 on: 14 November 2017, 08:05:20 PM »
you have the setting miles out you need to  take the carbs off and reset all the ajusters to normal and bench sink them first you proll  have the balance adjusters screwed in to  far thats how your idle is not working unscrew them out as far as you can then set your idle adhyster to control idle speed then adjust your balance

redmandan

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #38 on: 14 November 2017, 08:29:12 PM »
I'm sure you're right daviee but the reality is hard to accept. I just got it all back together, drain/re-fill the coolant again, fiddle about getting the intakes on and off again, getting the fiddly throttle cables off and reattached....

Can anyone tell me exactly how the idle screw works? I understand that the balance screws adjust the pitch of the carb flaps relative to one another. Does the idle screw adjust all flaps equally then, or does it work in another way?

daviee

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #39 on: 14 November 2017, 08:47:30 PM »
basically the idle adjuster is a throttle stop where the cables turn they pully that opens all the butterflys the same the idle adjuster  stops the pully closing to far if you have all the balance adjusters screwed  to far in the will  hold the buterflys open thats why your idle adjuster is not working and if you have your throttle cable adjusted wrong it can affect it aswell that why i said you need to start from the beginning bench ballance the carbs reset the cables etc as you have prolly everything out from where it should be 

Hugh Mungus

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #40 on: 14 November 2017, 09:09:04 PM »
Find the basic settings (must be in a book somewhere or on internet if one of these fine folk don't know.) Set all the carbs to the same settings, adjust throttle cable and idle screw. Then start the balancing process again.
No need to take anything apart. Yet...
Pat.

Disorderlypunk

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #41 on: 14 November 2017, 09:18:57 PM »
if i get my new jets tommorow i will have a look and if i see something i will try and do a little video of what is going on in that region
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tommyardin

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Re: Last job is to balance the carbs, and I can't seem to get it right
« Reply #42 on: 14 November 2017, 10:36:34 PM »
:agree


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