Suggestions on carb settings please

[Padders]

I have a set of 29mm smoothbores fitted to the Z1000. It ran fine before with a Kerker 4 into 1 and individual filters. I have now fitted a standard airbox and a set of Motad 4 into 2 exhausts. As such its running a bit rich (plug chop confirms) Before I pull the carbs out I want to ensure I have some jets of roughly the right size ready. So all you carb experts what jet sizes would you recommend plus needle advice higher lower middle?

Cheers

[Pigford]

Leave the needles until you've sorted the main jets out.....
Go easy, reduce by about 5% first change... etc

[ash]

29mm smoothbores dont really like an airbox, they are really set for race,

[timdaker]

Can't help feeling that it's a bit like hitching a cart to a racehorse. The standard airbox is the first thing to get rid of if you want extra performance isn't it? well that and the original exhaust.

[RALPHARAMA]

Not too sure that's the case - Steve Debben wrote a very interesting post about original air boxes recently. I have had many bikes with K & N / S & B filters, but in fairness I have found overall usable road performance to be best with a standard air box. Sometimes a more free flowing filter can be added to a standard air box. The fact that the air entering the carbs is still and even rather than being effected by the bike speed etc is easier to deal with.

[debben1]

Hello Padders, not to much experience with Motads but would suggest a starting point of 120-125's although the needle position normally has more effect on fueling at part throttle than the main jets, assuming you are trying to improve part throttle running than full throttle running then experiment with the needles positions first, (also saves spending money).
Airbox will work well with these carbs, fitting the airbox with my RFS38's really improved the fuelling and gave me the best 1/4 mile times over open or with velocity stacks fitted. Regards, Steve

[Padders]

Cheers Steve will be having a play this weekend. any news on the exhaust I sent a pm yesterday.

padders

[debben1]

Hello Padders, PM now read and been replied to, Thanks, Steve.

[chrisNI]

fitting the airbox with my RFS38's really improved the fuelling and gave me the best 1/4 mile times over open or with velocity stacks fitted.

Did you have a K&N in there Steve?

[ash]

Steve it does restrict it though, most drag racers iv seen dont use an airbox but if it worked then fine, when i raced i used twin 40 webs on my zed with no airbox or filters and it flew, its great to just put the 29s on and not mess with jetting and the likes, Go for it Padds

[debben1]

Hello Ash, most drag racers now spend long hours building the airbox, the prostock guys who have to utilise very fine tuning to get results as they are unable to rely on nitrous oxide or turbo charging for there power gains spend hours turning the inside of the body kit into a huge airbox, sealing off every contour and bend so that when the one piece body kit is fitted it creates a seal against another cover which fits over the engine and around the carburretors to create a huge airbox. although my bike is only in the streetbike class I wanted to experiment with these ideas, look at the quick street bikes like the GSXR1000 and ZX10R, remove the airboxes and the power loss is considerable even with out ram air effect. By using larger rubber type velocity stacks into the airbox to match the 38mm inlet tracts gave better results than airfilters or velocity stacks on there own, the airbox was opened out to take the larger venturis, turbulent air before the carburettor is prevented when the airbox is used, quarter mile times reduced by nearly 2/10ths of a second with the airbox fitted, this was after many race meetings of trying various set ups, hope to get the bike into the low nines this year with the new ignition system without the use of Nitrous. Ultimate aim is to get the streetlegal Z into the 8's, without nitrous, but we will see Best Regards, Steve

[ash]

Thanks for that Steve, always good to hear latest info from the guys who are racing today, wish i still could, my days of racing with the likes of Buzzard and Hunter on his Spondon s seems like years gone by,
Good old days
Anyone one want to buy my 40mm / 45/ webber manifold to put on you z1000 head? Carnt see me using it again.
Regards, ASH

[Rich]

Ian - what does it have in 25 pilots, 125 mains? Are you going to be using a filter in the airbox? You could probably do with going to 20 pilots and start about 110 mains. Play with the airscrew to start with for the pilots, if you go over 1 3/4 turns out go for smaller jets.

[GregZ]

I am runnig a stock 900 with 29 smoothies. I have yosh 4-1 with baffle installed. Stock airbox. Needle on the 3 clip. 115 pilots and 117.5 main jets ,air scew 1 1/4 out. Bike runs great.Very windy last weekend and I experimented in the wind riding. Bike pulled hard in all gears .
Very slight hesitaition from rolling take off so I may up the pilots to 117.5.
gregz

[Padders]

Cheers guys for all the suggestions. I have altered the needles one notch and it seems better. Have decided to go back to a 4 into 1 so will wait until I have that pipe on to make an further changes.