FIRST OF ALL ,JUST LIKE TO SAY HELLO TO THE FORUM,IM NEW TO HERE AND TO YAMAHA,heres the story,,last night i bought a 96 yzf,it was from shagger hes made a couple of posts on here about the bike,it has a starting problem,i was told that it would not start on choke,, it now appears its just a complete sod to start at all,when i press the strter it will not fire up although it sound like its doing its best to fire up,,, but as soon as you touch the throttle it just doesnt want to know,i was told that the carbs are flooding ,but theres not much smell of petrol,i was told that the floats want setting,but why was this not done as a lot of other jobs have been carried out to try and sort it,,,its had the carbs balanced,new coils and leeds and ht caps,,its had every size of mainjet fitted..and the vac tap as been relaced with a 2nd hand one,im going to make a start on the bike tomorrow and would realy appreciate any help,i will check the float needles and fuel height and the plugs,

doh forgot to say once the bike does fire up [somthing ive not managed]and warms up it runs great ,,,

sorry for such a long 1st post cheers Ged

Hmmm...

Just having a think.

Why should it run better when warm as the fuel in on the cold side of the engine. The only thing that comes to mind are the bores, rings and valves which might expand and seal better, have you thought of a compression test?

My thoughts excatly Lack of compression = no bang Let us know how you get on m8ty

i spent all of yesterday on the bloody thing,first i tried to start it kept it turning for a while,gave it plenty of throttle and choke ,then checked the plugs,they were bone dry,i was told that it was flooding that was the problem?????,,,,i checked the fuel height and it was 7mm bang on,i stripped out the carbs and they were very clean ,but gave the jets a quick blast of air just to make sure,put everthing back ,pressed the stARTER FOR 10SECS AND THERE WAS A BIG BACKFIRE BACK THROUGH THE AIR BOX AND A FAIR AMOUNT OF SMOKE,i checked the plugs they were soaked in petrol.triec to start it again and it fired up,but only at 1000rpm would not rev past this,then after 30secs vroom vroom it was reving straight over to the red line,,running perfectly normal,,left it for 2 hours and it wont start neither will it start this morning,stating the obvious there must be a problem with the carbs,also somone at some point as messed with the fuel pump,[butchered screws] also the vac tap,

the bike as only 13000 documented mile and a ful stamped service history up to 9000miles ,,and its a minter ,,,the only other thing is i know that it was stood for 3yrs in a garage an dnot used,,,ive only just bought it and i just be out there now on it the weathers great

right just been on the phone to a guy whose stripping his own track bike,ot a set of carbs ,,,vac tap,,and fuel pump for £60,,,he says it runs great appart from low revs when he said it feels like its going to die,,,he told me they all feel like that and i told him about mine and he said it was the fuel height ,[its not ive checked] the emulsion tubes,ive heard about theses tubes b4 causing problems,does anyone know where i can get these from [uk] ive seen them in the states but i need them urgent many thanks Ged

Think you're on the right track there GED.......that diagnosis does sound familiar with those symptoms

Think you're on the right track there GED.......that diagnosis does sound familiar with those symptoms

i hope so mate ,,the carbs should be here friday ,just trying to find a supplier for the emulsion tubes ,,who would be willing to post them,,,,,,,,,,,,,,,

Dry spark plugs, nice indicator there.

LEt us know how you get on the the other set of carbs.

THE 2ND HAND CARBS ARRIVED AND THEY WERE OFF THE EARLIER YZF,NO THROTTLE POSITION SWITCH,PUSH IN MAIN JETS,SO I REMOVED THE JET ASSEMBLY,EMULSION TUBES,NEEDLES AND SLIDES,I ALSO SWAPED OVER THE FLOAT NEEDLES,FROM THE CARBS I GOT TODAY AND FITTED THEM TO THE CARBS I THOUGHT I WAS HAVING PROBLEMS WITH,ANYHOW I PRESSED THE STARTER FOR ABOUT 15SECS AND IT WAS TRYING TO START I THEN GAVE IT HALF THROTTLE AND IT FIRED UP,BUT WOULD ONLY REV TO 1000 RPM ON HALF THROTTLE IT KEPT THIS UP FOR ABOUT A MINUTE THEN IT REVED TO THE RED LINE AND RAN LIKE A NEW BIKE,ALTHOUGH WHENTHE BIKE WAS RUNNING AT 1000RPM IT STANK OF PETROL...IT WAS DOING THIS BEFORE MESSSED WITH THE CARBS,IS IT POSSIBLE THAT THE CARBS MAY NOT BE AT FAULT,EXCLUDING ENINE MECHANICALS,COULD IT BE THE FUEL PUMP???THE VAC TAP???AND CAN ANYONE TEL ME WHAT THE THROTTLE POSITION SENSOR DOES???IT SEEMS THAT THE BIKE AS GOT A COLD STARTING PROBLEM AND GETTING TO MUCH PETROL IMMATERIAL OF WHAT THE CARBS ARE SET AT,ANY HELP WOULD BE GREAT AS I SEEM TO BE FINDING MORE QUESTIONS THAN ANSWERS,,,,

Too much petrol is usually a symptom of an incorrct float height or sticky/faulty needle.

I think your suffering enough Ged, you must be pulling your hair out!

jeez where to begin,,went to start the bike saturdayand it fired up on half throttle ran at a 1000rpm and stank of petrol after a minute it cleared and ran like a gudun,so its to much fuel,so i put the origional bits back on,the carbs are now as i got the bike ,it wont start ,,,dry plugs,,,so i start to swap all the bits over again to put it back as it was on saturday morning,,,but it still wont start looks like no fuel ,,,the only differandce is the needles are the origionals as the ones that came with the carbs i got are totaly differant ,so im at a complete loss,,,ive spent the best part of 17hrs non stop and im still no better off,all i can do is wait for the new emulsion tubes .needles and plugs to arrive,,,put the carbs back as they were,,, if it still wont start then ill have to put it in a garage, jimjam icve had the floats at every possible height and it makes no differance,the bowls are full of petrol,but the petrol isnt making it to the plugs,,,and theres no blockage also the throttle pos sensor is fine ,anyhow im off to find a short length of rope

the bikes running ,,,it had the wrong needles fitted ,,put the correct needles and emulsion tubes in and fired up great,its a bit lumpy on tick over and maybe a bit too rich but it needs a good run out ,,,which is what it will get as soon as hurricane hilda blows over

Woohooo well done m8 Now she`s running wouldnt it be worth while having the carbs setup at a dyno place? I know it cost`s money but must be worth it to save on stress?

If you live near manchester give jim a call at quill exhaust`s link here http://www.quillexhausts.com/index.php

Tell him lee from grimsby put you in touch What he doesnt know about setting up bike`s isnt worth mentioning m8 His dyno setup`s are very cheap aswell compared to other`s ive seen aswell

....I SPOKE TOO SOON,aarrggh,put me leathers on yesterday went to the yam and it wont start ,so i had one last look at her and all i can say is theres no petrol getting to the plugs.there totaly dry when i would of expected them to be pissed wet through,[plenty choke and throttle]

the reason it started yesterday was because b4 i fitted the airbox i squirted some petrol into the inlets,this was enough to get it to fire over and once warm it runs great,i also fitted a different fuel pump and tap,all to no avail,i think for the first time in 21yrs off messing with cars and bikes i will have to admit defeat and take it to a garage.the real puzzling thing is why is there no petrol when its cold and when its warm it runs great[even the correct colour of plug]

if anyone can recommend a good garage that can collect the bike [bolton /manchester area ]i would be greatful .

finally fix it and shes runnin like a dream,the carbs had the wrong profile needles fitted stopping the bike fuelling correctly on 2and 3 cylinders,it was overfuellin like a sod i put the correct ones in which meant that it was over fueling even more also the plugs on 1 and 2 pots were shot not giving a strong enough spark,the cure put inn the correct parts spend the best part of a month stripping rebuilding and resetting the carbs over and over again ,add 4 new plugs and hey presto,it works tomorrow i shall be phoning in work sick filling her up with the finest optimax and dissapearing into the lancashire country side

a BIG thanks to everyones help esp to shaggar [steve] the prvious owner for his endless patience in answerin my telephone calls,

http://www.allensperformance.co.uk/index.html

https://www.fowlersparts.co.uk

These are sites I used for parts.

Wow that HAS to be the oldest thread to get a reply in quite a while, after 8 years you may not get a reply.

Think we shall lock this one eh.