Air screws / throttle balancing

[scotty]

I'm having a problem getting the air screws set properly prior to balancing the right hand throttle linkage with the twinmax.

I'm initially setting both air screws at 1 1/4 out from being lightly seated. With the engine warm and the twinmax connected this is producing a tickover which is too high and the higher I turn the sensitivity knob up the more the needle pulls to the left. To get the needle back to 0 I have been closing off the right side air screw and the only way I can get the tickover about right (with the needle over 0) is to turn the right side air screw all the way to almost fully closed position which seems wrong to me as there is then a massive difference in openings between the left and right airscrew setting. I believe there should only be about a 1/2 - 1/4 turn difference. If I turn the sensitivity knob down then I can get the needle hovering over 0 without too much trouble but this is somewhat defeating the object of the exercise. On max sensitivity I have also noticed that when I open the throttle up to about 3,000rpm the needle pulls one side of 0 and then pulls the other side when the throttle is closed. When carrying out this adjustment before the needle always pulled in one direction and then settled back at 0 on closing the throttle however this situation may be caused by the airscrew settings being out

The first thing is to get the air screw settings correct and balanced on the twinmax. Any tips here would be greatly appreciated. I must be doing something wrong or should I just forget about trying to get the tickover balanced on the max sensitivity setting ?

Cheers

[winger]

Have to say i've never touched the air screw on the left side in 7 years,or the cable for that matter,i always run max sensitivity as thats the whole point!!,you'll have to ajust both air screws to get the tickover something like,mine runs bang on a 1000 like a watch!!!.

The bit about opening the throttle at 3000,thats as per the book,why are you worried about closeing the throttle!!! it's a steady 3000,hold it at 3 and sensitivity on max and lock the nut off on the cable,i've found it all but impossible single handed,as locking the nut off upsets the sensitivity,you need 1 person holding at 3/4 thousand,so you've got both hands free for locking the nut,and undoing it when the needle moves just as you tighten it up!!!

Going back to the airscrews,your going to have to roughly do it,before you put the TM on,although i have to say,my airscrews maybe out as far as yours i've never checked.

[scotty]

Winger

Like yourself I was only carrying out adjustments on one side and everything was fine. Cannot recall know why I wanted to know how far each airscrew was out but I've altered the settings now so will need to sort. As I understand the twinmax settings.........if the tickover is too high and the needle is pulling to the left then the right is the weak side so one srews in the right airscrew clockwise to shut off air. If I do that I can get the rpm right and the needle to balance over 0 but only with the right airscrew nearly totally shut off which cannot be right. Infact I am now suspecting that the right screw may well have been like this all along. Would this be symptomatic of a problem elsewhere ? Surely one airscrew should not be almost fully closed off.

I'm also wondering how critical the airscrews are to the running of the bike. With fuel injectors/sensors etc the air/petrol mix must be reasonably ok regardless of where the airscrews are set ?

[winger]

Sorry can't help with that,for all i know mine is the same,i've never checked,you'll just have to start from scratch,concentrate on getting the bike running OK first and worry about the number of turns!!! latter.

[mdouglas]

Take all the tension out of both throttle cables first. That way you will know that the throttle cables are not holding one of the butterflies open at idle (which would cause you to compensate through the bleed screws). There are separate butterfly stop screws that determine their rest position. (that you are not supposed to touch and are painted blue once set at the factory).

Set the idle speed and balance with alla the cable tension dialed out and then sort out the cable tensions so that the two throttles open in sync.

[Boxadog 2000]

Wot he said spot on

[scotty]

Thanks Guy's

I managed to get things sorted last night by tweeking the air screws when the engine was cold. I also squirted some WD40 in the end caps where the throttle outer cable beds into the adjuster cap just to meke sure there was some free play. This time round, and with the engine cold, it was fairly easy to get the tickover set right and the twinmax needle balanced on max setting. Both air screw adjustments are now much closer together which is how they should be. Christ knows what was happening before. This time round I removed both fairing panels and made sure the right throttle cable was routed correctly and then used the WD40 to make sure nothing was sticking where it should'nt. I think it's pretty much spot on now though and I've balanced to about 1050rpm rather than the usual 1150rpm. Well, now I've only got to fit the hugger when it arrives from Sandbar as the back of the bike if full of muck at the moment. Was looking forward to a good weekend tomorrow but I think there is more crap weather on the way. This summer has been a complete joke.

[nab 301]

Thanks Guy's

I managed to get things sorted last night by tweeking the air screws when the engine was cold. .

Did you check the valve clearances before attempting to balance the throttle bodies.?

Nigel B.