still having probs, flat spot and spluttering

[lewisdale]

me again!!lol, well my bikes now running but, seems to have a flat spot from about 6-8k then after that splutters all the way to 14k!! ive been informed my jets are#102 and my airbox has got the front missing(new one on way) does anyone have any ideas? fuel system has all been cleaned, new cr9e plugs,new oil,new leads,new coils etc!

[zimm]

what do you mean by the "front missing"? the snorkel bit ?

if so, thats your problem, and its running lean as there's too much airflow, put a piece of gaffa tape across the bottom of the square hole in the airbox where the "snorkel" normally goes.. just make the hole 10mm smaller .. should run better.. its what we had to do to mine on the dyno to get it right when in a hurry and no time to re-jet.

sadly though.. if this fixes it and it behaves just like mine.. it'll be too rich with the snorkel fitted.

[lewisdale]

well i have got the airbox bolted onto the carbs and the filter is sat inside it, but thats all i have, no front? is that what u mean by snorkel?

[RedexRobB]

its the whole front peice of the air box Zimm. Hes got #102 main jets with standard down pipes and that MRS can (sounds very good). I thought they might be far too big for just an end can though?

[zimm]

ahh k ..

lol, yeh.. there's no way it'll pull cleanly with half an airbox..

shoulda said mate, i've got a few spares here:)

102's wont be far off .. needles matter more than being a touch rich at the topend, a dyno will see it, but seat of the pants wont, H's were #98 stock compared to L's which ran #95's..

horrible ugly dirty hack untill you get an airbox front, gaffa tape over the filter to restrict the airflow, add some, ride it, add more if needed, 2 or 3 attempts should get it pulling cleanly.

[lewisdale]

hello mate well ive just bought a complete airbox off ebay but im going to try to get hold of bigb in the meantime to see if hes got the origional front

[lewisdale]

and thinking abut itm it wasnt to bad in first gear, and obviously the faster i go the more air its gonna get which will make it very lean, it was worse in the higher gears

[RedexRobB]

102's wont be far off .. needles matter more than being a touch rich at the topend, a dyno will see it, but seat of the pants wont, H's were #98 stock compared to L's which ran #95's..

So why is my L staggered with #88 and #90's

[zimm]

102's wont be far off .. needles matter more than being a touch rich at the topend, a dyno will see it, but seat of the pants wont, H's were #98 stock compared to L's which ran #95's..

So why is my L staggered with #88 and #90's

dynojet jets or keihin ?

either way, probably because its been dynoed with a stock filter and exhaust, and setup like that .. my L4 was the same. Staggered jetting isnt OE afaik

with jets that small, its possible you have the restricted (smaller) carbs too, as did my L4.

[lewisdale]

how much gaffer tape shall i put on at first? a lot? 3/4 of the front?

[zimm]

strip across the top of the filter and work down from there if it needs it.

let us know how you get on

[lewisdale]

i will do mate, thanks,might even do it today lol

[RedexRobB]

102's wont be far off .. needles matter more than being a touch rich at the topend, a dyno will see it, but seat of the pants wont, H's were #98 stock compared to L's which ran #95's..

So why is my L staggered with #88 and #90's

dynojet jets or keihin ?

either way, probably because its been dynoed with a stock filter and exhaust, and setup like that .. my L4 was the same. Staggered jetting isnt OE afaik

with jets that small, its possible you have the restricted (smaller) carbs too, as did my L4.

Keihin jets. I thought staggering was pretty normal according Rover220 in one of my previous threads? Im gonna measure them up sometime soon as i need to get the tank off and fit the idle adjustment cable i bought new. May take the opportunity to put in #102's in while im at it, although if they turn out to be 30.5mm carbs wouldnt i need to be thinking about different ones?

[lewisdale]

wehayyyyyyyyyyyyyyyy, sorted!!!!!!!! finalyy, had to cover the airfilter about 99% but it flew after that

[zimm]

Keihin jets. I thought staggering was pretty normal according Rover220 in one of my previous threads? Im gonna measure them up sometime soon as i need to get the tank off and fit the idle adjustment cable i bought new. May take the opportunity to put in #102's in while im at it, although if they turn out to be 30.5mm carbs wouldnt i need to be thinking about different ones?

staggered jetting is common, but its not "standard" mine will be going to staggered jetting when i can be fecked to get it on a dyno, the pipes off 2 and 3 blue up a lot quicker than 1 and 4 with all the mains the same, which indicates that the inner 2 do run a bit hotter.

our zx4 ran better with the original beet system after i chucked #100 mains in it.. but thats the only time i've ever bothered twitting about with the smaller carbs... zx4's run #95 mains stock, but its a diff airbox again, (like an H but bigger) and hotter cams. Ultimately the 32's are better.