will be fitting some cbr 600s to a 1.6 abu ,what size jets shall i start with ?,untill i can get to a rr to get it set up properly thanks

id say 130. that should get you up and running through the rev range as a start and then as you have said a rolling road to get it done properly.

good luck.

id say 130. that should get you up and running through the rev range as a start and then as you have said a rolling road to get it done properly.

good luck.

They're 130/132 as standard. I ran them standard in an AEE and it was very lean,slow. I ran them fine at 150 but it still lacked power top end,id run them 145-150 on a 1.6. to get to the rollers,where they'll be opened further.

thanks guys ,i so cant wait to get this thing going when i do a pics going on here :-D

130 as standard the ones in my cbr600 were 118's! but never tried them standard, just drilled to 150 and they didnt work well, found some 132 i think they were and that sorted it a treat.

600 cbr's (year dependant) ran different needles... you can richen them up by sticking them in a drill and holding some fine emery paper to them (try and stay away from the end of the needle, mearly let an edge just hang over it as you sand the body of the needle) obviously the thinner you get the richer the mix and the further up the needle (to the holding end) the higher rpm you effectivly alter the mix (presuming your springs are setup right..)

to soften a spring SLIGHTLY then squeeze it together around 1/3 (so if its 9cm squeeze it to 6cm ish) with a nut/bolt and a couple washers.... then throw it in the oven. give em half an hour.. once they cool they should settle at a smaller size giving less pressure.. or cut them but ffs do it one ring at a time and CHECK what they do. the problem being they can fall out of there holder on quick throttle/off action. pulling them apart to give you more stiffness will simply make them almost impossible toi match and almost always WAY toos stiff.. the springs are readily avalable in different weights. jets/needles/springs/atomisers/polit's/choke's are all VERRY cheap consumable parts. yes you can bodge it together and it will probably work better than the stock item (made me chuckle mikey ) but its best to set them (give yourself an idea) with such bodgery then order specific replacments..

bottom line is if your gonna be messing wiht carbs your gonna need spares like this. no 2 cars will ever run the same on aftermarket carbs (theres too many variables, even wiht stock engines) so you may aswell stock up on some spares your going to use in the future.. means longer life and a better understanding of your engine at the end of the day.. i can't think of a better way to waste a week/50 quid than a whole load of jets/needles/springs and gettign the thing spot on in every gear, every rpm

or maybe i just have an unhealthy dislike of flatspots? :p

just an FYI, my jets came to £2.45 each from allens performance, drilling jets can kiss my ass when they are that cheap.

runs miles better with a 135 jet currently

didnt trust my first jet set hey ant??!! LOL! bring it round! show me what you have been doing.

I drilled the jets in the carbs ha haaa

Got a few different sets on order from allens performance so hopefully with the use of my new wideband set up I can monitor what the chuff is going on with my carbs/engine.

I will bring it round in a few weeks, need to sort a few niggles out atm

Ant

Drilling jets is accurate,but sanding needles.. You'd never get the profiles identical.

If anyone can find a supplier for alternative needles I'm all ears.

Humer - the carbs are '99-01 type. Yeah there will be differences with older sets.

allen performance is the one for jets/needles..

sanding needles is easy, you can messure them/profile them wiht a vernier caliper a peice of paper and a pen.. a jet you CANT get a guage in and again, if your drilling them they need to be centred (again, by hand a hole naturally wanders up to .2 even with the steadiestr hands, thats a variatoion of 20 jet sizes.. not accurate... also drilling causes markes.) jets are drilled, reamed then polished.. a jet drill is bodge.. it NEVER comes out trhe size youj plan for.. as for drilling them in place. thats just asking for a dead engine.

reprofilling needles is sudgested in every tunning manual I've ever seen and is a largly common thing to do/especially edasy to get accurate.. all you need is a profile table (layout wiht all the needles and a key of how to messure them) and again, draw the needle.. messure a length from the top, then a thickness at this point, you can make any needle from a thick needle (I've made needles from nails befor now) but again, its easy to m esasure.. a jet is near impossible to messure after drilling. and yes, there a couple quid.

you can buy a box of 20 jets in any size you like for 9 quid, times it by 4 and its 36 quid for every jet you will EVER need.. needles arew easy to find.. google "keihin carb needles" READILY avalable.

had a little idea about setting up without a dyno.. if you can hear lean/rich and set the timing up by ewar the spring/needle can be set quite easily using a security camera ands small screen.. drive the car wiht the cam facing ionto the carb... can see how much the slides oppen at what rpm in what gear at what speed.. write EVERYTHING down adn figure the happy meduim. or pay somone 90 quid for an hour on the dyno and 4 springs/jets/needles

how are you all balancing your carbs? or is it a case of "they came off a running bike, the idles will all be the same"? running them out of balance at idle will seriously confuse the bogging/flat spots on first throttle... if your getting a slight misfire on first throttle/comming off the throttle you need to re balance the carbs. (well, you should do this every time you so much as touch the idle speed master control) a cheap single guage you place in the venturi is good or if you can gab 4 vac guages (made for this job) and set the idle speeds up through all the carbs..

theres so much to go through tbh, mikey.. if yours was lean at slow speed wiht the small jets it is nothign to do wiht jetsa.. the needle was wrong (too thick near the top/slide~) if there fine at fast engine speed wiht the 132's then there fine, change the needles.. now your running flat as hell rich at top at the expense of bottom end fueling wich should be ajusted with the needle... meaning your wasting effective fueling. try the 132's back and ether buy diff needles or use the method above to reduce the diameter of the top of nthe needle... it will be thicker than the rest.. if the needle is fairly straight/flat then its deffo not right for this sort of application as it should be a taperd needle, the taper will cause even richer full throttle/fasat speed mix so you might get away wiht a thin needle and a 126 jet..

but ye, some more semi usefull links...

http://www.carbparts.com/keihin/needles_tu...g_your_carb.htm

http://www.ducatimeccanica.com/needle_chart2.jpg

http://www.iwt.com.au/images/chart1.gif

http://www.rcaer.com/pages/files/walbro_chart.jpg (not slide but the butterfly diaphram all the same)

these are based on the oko (Chineese copy) pwk carbs.. http://www.oko-australia.com.au/sitebuilde...les/needles.jpg still almost identical needles

as always, if the people rolling road tunning your car are drilling jets/sandingf needles and cutting springs you need to find somwhere else... these are quickj solutions to hom,e tunning problems if your waiting for parts but in no way an accurate professional job.. put 2 jets on a flow bench (yes a bloody small one) and you will see they flow .2 out (if drilled in the same jig wiht the same single bit) also, who;s anodizing them for you after you drill them?

ima stop now, as i keep on and on... but ye, get reading/ggogling.. its amazing what you find if you spend 20 mins looking.

The tips of the needles dont reach the jets at all,the jets only govern the maximum amount of fuel the carb can draw. Therefore,the hole could be oval if it liked - as long as its the correct size.

With the drill bit hugged in the hole by the same tension as the other three,during its slow draw out the jet during drilling,the size tolerance between all four jets is absolutely miniscule.

They were drilled to 1.65mm,but a 1.66 bit wont fit in the hole. Kei-Hin themselves dont get them much more accurate than that,and i dont think 0.005 would even make that much of a difference.

Fair point on annodising,but the only problems I've had there were by running part bio ethanol. Wasnt good.

And you certainly couldnt get needle profiles that accurate - i certainly couldnt with my 1/100 Mitutoyo Absolute calipers and what,some sand paper?! Thats a CNC job and no less.

Needles must be new then,and i need some that reflect the nature of the long stroke AFH-cammed engine.

The needle profile just wasnt progressive enough with the CBR900 needles,which are more suited to the longer stroke 8v's. Fine in town driving but leaned out when working hard. Using more progressive CBR600F-X needles has opened up the mid-top under hard labour,but these needles have a step about 60% of the way open and that cant be ideal for the mixture in any engine unless it has variable cam timing.

Cutting the springs was the only way to get them the same length whilst retaining the same rate as eachother - this does increase the spring rate but the length chosen compensates that enough for now (the needle profile isn't ideal anyway,so its hard to tell what an effect this has).

Good economy and a recent MoT prove its not too ill,but i do need to get it on the rollers and try some springs,needles - and drill bits. Though i'll probably use replacement jets simply because they'll be quicker and easier to change,should pay for themselves on reduced labour time. And of course,I've never denied them to be preferable - i just dont see it so critical ime.

Yeah i thought of using the mobile camera for the slides (mine is only 4mp on video but it would suffice). I can almost see down them from the drivers seat,but just cant see the slides!

I cant defend my balancing technique other than to say it works well enough to give me a sweet,stable and legal idle - i take them off and use my mouth.

Cheers for the heads-up with the links btw.

i dont for a min want you to take what I've said as "dont do what mikey's done" as i never ment that, mearly anyone who ISNT too clued up wiht machining work going at there jet's wiht a couple wood bits.. all I'm trying to do is show people of less knowledge that its easier to just buy replacments and it IS hard for the ley man to just drill there jets/cut there springs.. lets face it, there are idiots abpout who take every word literally... i know they dont seat into the jet, they seat into an atomiser wich the jet screws into, the hole on this DOES line up with the middle of the needle (well, should) so at bottom revs the fuyel passes through the jet then hits the needle smack in the middle, splitting it across the needle.. the needle thus hjas to be fairly centred so the fuel doesent just rush up one side and completly miss half the atomiser.. this causes non atomised fuel to reach the venturi (will pop/spit and run rich to lean verry easily at idle) but ye, if your using reamer's specificly for stepping up jet sizes youl be ok and yes unless your using higher strength fuels than the rubbish we buy sat the petrol station the anodizing wont be an iussue (well, unless your car is left more than a week wihtout running.. ali turns horible real quick in fuel) for the cost of them tho its worth an amature just buying some... taking the advice about rouch setup from the board and then a session on the rr to set the needles/spring rates.. it is about the hardest thing to do yourself..

anything your stuck wiht/parts you cant find give me a heads up and ill happily see what i can come up with..

on a side note.. if you can almost see them just use 2 cd's as a type of periscope mirror.. only need to cable tie them in place for 20 mins till youve done all your driving or "undfer load" testing.. saves setting the cam up if you dont have a wireless security cam or the like. done this with mini's befor now (2 wing mirrors) just to get a look/make sure what i think is happening is actually happening..

again, you would be supprised how differently they run wiht the original airbox on (can get away with way leaner jets and the needles are completly diffewrent, plus the slides will opperate at a different rpm/vac) well worth trying out if you get 10 mins and have the original airbox lying about... will instantly richen everything up nicely so smaller jet/quicker opening on the slides (as you restrict air the vac increases, meaning your carbs work more fuel through a smaller jet, it also compresses the mix) whoever say's freeflow filters are good for performance is an idiot.. there better than a stock airbox once you reach its limits (usually fuel econimy) but ANY rally/sport specific car will have a box engineer'd specificly for the engine its being used on, the bike box will happily flow more than enopugh for anything upto a 2l engine (considdering a big 1300 bike revs to 13k happily) use an airbox :) makes things so much easier (especially if its the original fitted to the bike carbs) it WONT kill performance.. it literally kills noise and raises the vac pressure inside the venturi

I am tempted to have a bash with this airbox thingymaboby. scrapyard run to doncaster this weekend I think

Ant

I dont have room for the air box,but my filters are almost zero restrictive (just stainless gauze over an open-sided box) so it was basically tuned without one - mine would run like crap with the original air box,for the reasons Minor Confusion says.

hi its me again I've justt spotted that my carbs have 2 inlets and 2 outlets ,i was plannig on using the t piece as like mikeymk ,retaining my original pump.

will t piecing the return work aswell? thanks

Edited 3 December, 200916 yr by bmwe30init

Can you get a pic up of the carbs,showing these outlets?

Can you get a pic up of the carbs,showing these outlets?

I'm not to clued up on adding photos but when i got the carb ,the outlets had fuel hose on them and if you blow in the in the inlets with the floats down and lift up the carbs so there shut then you can hear it comming out what appears to be returns/overflow? i must have early carbs and my main jets were 135 fwiw?

I've had a look and written on the hoses that are connected to these out lets it says emissions/fuel so it still could be breathers or fuel overflow

Edited 4 December, 200916 yr by bmwe30init

The petrol pipes will be low down - any fuel linked outlets higher up will be vents.

The petrol pipes will be low down - any fuel linked outlets higher up will be vents.

cool thats what i want to hear ,so the t off method should still work. thanks

got a case of flat spot itus guys :(

jets are 135 instead of 132 i have no known air leaks but from 4000-5000 rpm it hesitates and then makes power again like a turbo kicks in so to speak

Any ideas?

Ant

No manifold leaks? Unbalanced butterfly chokes?

Jets sound very small,i was running 150 (originally 132) on a standard 1.4 ABD and it was only a little rich if anything. 145 would've been the lowest id have gone (0.05 isnt really accurate enough but i can only get bits in those sizes at the moment and will order ideal jets when i know precisely what to run). Slide rate is obviously a major issue though,these control the profile of the needle and thus your mixture at any given rpm so they must be right.

But if you've had it on the rollers these shouldnt be an issue,taking me back to manifold leaks or unbalanced chokes (though the latter should give more of an effect at lower rpm).

when i set it up i set it up using the co machine, checking the hydrocarbons and setting it to the optimum setting when at idle and then held at 3500rpm, which cleared up the hesitation.

have you changed anything regarding the mixture screws, springs, needles? i know you said you have changed the needles, but they have only gone up a bit from the ones i had in.

good luck, hesitation may be linked to over fueling as before you was hitting a huge flat spot at around 4000rpm, if you have checked for any air leaks etc.

Woohoo, the Mk2 is back together and running again after the saga with the clutch release bearing.

Had it running for ten minutes today but the fan wasnt kicking in despite the thermostat opening, so ill be wiring in a switch to do it manually.

also the bore of my downpipes flexi is greater than the rest of my system, so it needs sorting,only chance i can get is saturday, so just got to find a place that doesnt mind fiddling with systems and take it over there.

does anyone know the factory timing setting for these engines at warm operating temps?

i foookin cannot wait to give the car a wee blat

Also I used the following for my throttle cable

Weber throttle cable part number 99901628

Weber pedal block, part number 99901645

Throttle Cable Adjsut for the above

Weber Pedal Block was the perfect fit for the polo pedal, and the weber throttle cables end was a direct fit with no need for filing into the bike carbs throttle lever assembly.

the true acid test will be when its on the road, but it feels responsive and returns well, although not as quick as i would like. the cable has been left at its standard length, but will be shortened later, i jsut wanted to avoid bad routing and kinks at this teething stage