Carb balancing fail.
 

Hello all, a very distressing experience has just been had.
I was trying to synchronise the carbs today with a set of gauges I borrowed from my brother. Whilst using the gauges I found them to be totally duff fluttering all over the place with adjustments making no diference, so I gave up and tried to put it all back together again as I had had to go the long way round(radiator, airbox and obviously tank all moved/removed) and then I started her up and RAAAARRRRRRRRRRRR full throttle with me excersising my wrist in a nocturnal fashion all to no avail.
What in the name of the wee man have I done now?
The throttle is closed on the handlebars but she's revving her head off and backfiring like chitty.
Please help. :confused:

Re: carb tuning WTF
 

sounds like you have adjusted the carbs to rev higher, or maybe one of the valves is stuck open?

Re: carb tuning WTF
 

Have you replaced the two tubes you removed to attach the gauges? If not this extra air will probably cause it to rev.

The gauges will flutter if you don't have the damper tubes in place. Some gauges have a threaded moulding on the hoses you need to remove for use on the SV carbs. If this is the case, use two lengths of hose on each carb so you can still have a damper tube between your carbs and the gauge. Reading this makes it sound complex, but it actually isn't!

Hope this helps?

Re: Carb balancing fail.
 

The gauges have a screw on the face of them to adjust and stop the fluttering but they just didn't seem to settle. When I had given up I though it wise to leave a tube running from the front for easy access next time, but, I might have left it leaking slightly, would this cause the revs to stick?

Re: Carb balancing fail.
 

That would cause the popping. The tube needs a bolt sticking down it to plug it.

First things first what is it revving to? Redline or what?

Re: Carb balancing fail.
 

Yeah revving as much as it can. I have just replaced the plugs as well but don't think this is connected?

Re: Carb balancing fail.
 

dislodged the throttle cable or snagged it..

Re: Carb balancing fail.
 

Did you take the cabs off at anytime? Check that you dont have anything trapped on the throttle linkage and that it moves and snaps shut...on both sides of the carbs. If you removed the throttle cables, then have you put them on the right way round? Again check the throttle action and the linkage action for signs of this. Air leaks will case popping and poor idle more than revving!

The easiest way to balance carbs for the 1st time is to remove them form the bike, fit a length of tubing to the front inlet, then but all back together, then as said but a sutible bung/bolt in the pipe. You then balance the cabrs with the bike warm adn the airbox on, although i always do mine with it off!.

Re: Carb balancing fail.
 

Thanks for the advice I'll go and check to make sure I haven't snagged the cables on anything and make sure they're closing properly.

Re: Carb balancing fail.
 

Connected them backwards perhaps?

Re: Carb balancing fail.
 

Hmmmm all very strange, I hadn't actually removed the carbs but checked the cables and made sure they were closing properly. Dunno if upon looking I had done anything but it all seems well now, reving and ticking over, so a big thanx to all.!!

Re: Carb balancing fail.
 

I remember when I accidently crossed over my CBR throttle cables when I took the carbs off, that was errr......interesting :rolleyes:

Re: Carb balancing fail.
 

Mine is running, sounding really quite cool, big throaty growl, but the cylinders still seem to be in the huff with each other and "hunting" I think best describes the idle.

Re: Carb balancing fail.
 

If the carbs wouldn't balance up you need to check the idle mixture screws and the valve clearances.

Re: Carb balancing fail.
 

Idle mixture and valve clearances???? eeeee god the plot thickens, gonna try and get a working set of gauges and try again, hopefully that will be all that is needed.

Re: Carb balancing fail.
 

There is also the possibility of knackered gauges!

Bear in mind the reading is pulsing naturally (4 stroke cycle, innit). Did you have the damper screw closed far enough?

Re: Carb balancing fail.
 

Yeah I turned it as far as it would go one way and then tried it the other but they still fluttered or rather spun round this way and that. I think the gauges were err very cheap off flea bay so I'm happy enough to presume them duff.

Re: Carb balancing fail.
 

I don't get this at all!
I've taken the air box off to get to the adjuster screw on the carb and now it won't tick over and if I rev too hard it just cuts out. I had another go with the gauges, as pointed out to me I hadn't set them up properly (tube into valve then into gauge ) but now it won't tick over at the appropriate speed for me to adjust.
Can I rev a little and adjust from there or does it have to be done with no revs at all?

Re: Carb balancing fail.
 

Turn the idle adjuster up a bit, it makes it far easier to have a stable idle.

Re: Carb balancing fail.
 

Just a quick update, apparently I'm a male sexual organ.
When adjusting the carbs, the tank is up and disconnected, so therefore after a wee while it runs out of petrol.
DOH!
Anyway all done now and running sweet.
Thanks for your time a patience.
I'm gonna hang my head in shame now. (scuttling away into a corner donning a dunce cap)

Re: Carb balancing fail.
 

Sookie , look at it this way , you have provided a thread for somebody to reference to on a search when they have this problem in the future , or you may be able to help them yourself , it`s all good at the end of the day . I balanced mine the other day on my Pointy K3 and next time I do it I will find it all a lot easier , now pass over the 11" 45 degree bent nose pliers please :)

Re: Carb balancing fail.
 

Try both gauges on one carb in turn - see if they both read the same before adjusting, set the dampers as well - gives a more accurate reading.
Even if they're not able to be set them so they read the same at least you'll be able to allow a correction that will allow you to use them.

Re: Carb balancing fail.
 

You'll need fuel - tee the tap into the vacuum line for that carb. It also sounds like it's running lean, which makes the needles flutter and it will run worse without the airbox, worse still if you have a loud can and not rejetted to compensate. You can work around it though, take the airbox off, remove the appendix collector thing on the left side, put it all back (block up the holes), and you can run it with the airbox and with access to teh adjuster. Finally I can picture the gauges you mean, multi-coloured faces, and they're utter crap, a decent set doesn't have any damping screws. I've used them before, they're worse than useless.

Re: Carb balancing fail.
 

Its really bugging me now, I've balanced the carbs but it still don't sound/feel right. A bit slow on the uptake, like meself, and hunting. Gonna get something to put through them to clean them out and see if that helps.

Re: Carb balancing fail.
 

Have you got a totally stock exhaust etc. on the bike? cos from all you've said it does sound like it's running lean. That could be a blocked jet, though, if the setup is stock, but adding a louder can does need the carburetion modifying to suit.

Re: Carb balancing fail.
 

Its a stock exhaust just now as I had to take the louder one off for the MOT but I think everything has been left alone just a different can stuck on the end, to be honest I'm not really sure being the apparent 5th owner of the bike.

Re: Carb balancing fail.
 

You balanced your carbs on a pointy?
I thought they were fuel injected.. :confused:

Re: Carb balancing fail.
 

Throttle bodies need balancing too. :)

....

Sookie,

I have mentioned this before. My experience with mechanical gauges indicates that they are best stored permanently... in the local landfill.
Make yourself a water manometer. They are far more accurate for balancing carbs than any gauge. No calibration required. The aim is columns at the same height, although a couple of inches won't make a bit of difference and you'll see that (probably more) anyway because carbs generally don't balance equally at all rpms. There are plenty of plans for home made manometers on the net.

Here is one: http://www.obairlann.net/reaper/moto...manometer.html

The only thing that I do that is substantially different is to run the hose to each cylinder (as indicated on the linked page) back down to the base and add a bottle into each line that is just sufficient in volume to hold all of the water in the system - it is not a lot, less than 100ml. I also use 10mm ID tubing for the main part of the gauge (easy to see and easy to fill - the small stuff is very hard to fill) and 4mm ID (I think - use what fits) for the hoses from the bottles to the carbs.

Also, a couple of fuel filters make fine dampers for gauges.

Cheers

Re: Carb balancing fail.
 

I never mentioned Carbs once , Back to school for you :smt081

Re: Carb balancing fail.
 

A big thank you to MattCo.
I now know what this weekend brings.

Re: Carb balancing fail.
 

I know :rolleyes:
Bit like saying "yeah I adjusted mine too, tyre pressures that is" in a thread about headlight adjustment lol...

Re: Carb balancing fail.
 

Not at all. :) Think about your analogy in context of this thread... Carbs and TBs vs tyres and headlights... :)

Cheers

Re: Carb balancing fail.
 

Fine, you win! :lol: