still got carb trouble!

[1992divvy]

hello again! this fzr is really doin my swede in now>:) a few months ago i was ere asking for help with my fzr's carbs. well after stripping,cleaning rejetting and replacing also a litile swearing i am almost at the point of counselling! now its starting point settings were- 110 mains,2.75 turns pilot,second pos needle clip(out of 7!),K&N drop in,fzr400 slides,24mm float hight. now on that it started idled and reved freely while standing still but just died when trying to ride away. settings that im at now are- 106 mains,1.75 turns pilot,needles 2nd clip no washers or plastic spacer,replacement needle jets,22mm floats and same filter. oh exhaust is micron 4-2-1 with art series 2 race can. now it starts,idles and revs cruelly,but once its been running for about two mins it hits a flat spot which if you twist open the throttle slowly it splutters and almost dies(tried opening the choke and it made no difference!) however if you just snap it open it just misses very slightly and buggers off up the road like a good un! now on my own its frustrating but nearly impossible to ride slowly through town(30 mph) unless im in first and its a tad loud for that! . any ideas cos im fast loosing the will to live! any help would be great chaps. oh has anyone got a set of std needles as its the only thing i aint tried,im in the UK by the way. ride safe. del.

[pnbell]

Well, it sounds like your problem area is mostly low end throttle:

-The the carbs been Sync'd?

-You Said Pilot Screws are only turned 1.75 turns? This seems too lean of a setting, mine are closer to 3.25 turns out...

But this low end hesitation is most likely related to: Carbs being out of Sync and/or Pilot Screw Settings

[pnbell]

p.s. You have a High Flow Air Filter, and High Flow Exhaust, but yet you every change you have made seems to be providing less fuel.. Generally when increasing Air Flow, you'd want to Increase Fuel Flow too. Am i missing something?

*When you rev' the engine: Does it hang at a higher rpm before returning to idle?

[1992divvy]

hi mate thanks for the input! i know about the high flo bits and up jetting to suit,but if i do it only just runs (110 mains and 3+ turns on pilot) it will almost stop running if i try riding with those settings thats why ive leaned it out to get it running this well! went out today and changed the needles for some fatter ones(similar to stock) to try that and it started ok(no choke but its not cold here) and yes it did hang after a blip so i opened up the pilot to get a smooth idle and no hang or dip. popped up and down the road and just about 1/8-1/4 throttle in second on a light load it coughed and spluttered so quick twist and it pulled through and revved cleanly. yes carbs are all pulling together all bang on level! now i know the needle jets can cause all sorts of grief but ive swapped mine over from another set and got exactly the same results! my other needles have a long thin taper compared to presently installed needles as i could not drop em any further i swapped to the others. now one bit i dont think i mentioned is that i think i have fzr 400 slides which have 3mm damper holes and 600s have 1.75 holes. ive sleeved mine to as close as i can to 1.75 and im not sure if they are now moving to slow and causing a rich period just on transition between pilot and needle? would seem logical as they now need less vac to rise and open said fuel system. as i said once you get past the bad bit it goes well enough to spin up the rear in first halfway up my street without clutching it! also the front wheel gets very light just on rolling acceleration! its just the sticky bottom end . grrrrr!

[pnbell]

Cool, well it sounds like you have made some positive progress. You said you swapped the needles, but did you ever check the Emulsion Tubes for wear? The opening gets oval from the needle vibration over time, which causes them to leak fuel before they should. (This is very very common with FZRs; and i'm sure you've already heard this)

Also, if you have not sync'd the carbs, this could be your low end hesitation. Out of Sync carbs will produce inconsistent power from each cylinder and hesitant or jumpy acceleration at low throttle. Out of sync carbs affects all throttle positions but is most noticeable at lower throttle.

[1992divvy]

hi again! well ive given up on the carbs,going for another set as i think mine have been messed with (before me getting in there!) too much and it is going to cost more than the bikes worth just to sort em out, £280 for pattern slides,£50 for needles and £150 ish for jets and then it may not work if the bodies are shot! so got a good working set coming to bolt on then i can ride and maybe sort out these or part them out as the slides are in good condition so they may help someone's 400 to live again! ill let you know how it goes as they should be here by next week. thanks for your help so far,gave me things to think about! ride safe....

[pnbell]

cool, let us know how that works out.

[1992divvy]

hi all,back again as promised! now i put the new(second hand!) carbs on didnt touch a thing and the little bugger fired up first press and ran ok! let it warm up a touch and blipped it and no probs,sounds different too so let it warm up some more( buggered off indoors and had a brew!) come out and although a little lumpy( bearing in mind i didnt even clean em just took em out the box and put em on!) was still100% better! stuffed my vacuum guages on and they were quite a way off so a bit of tweeking and sweet running was resumed. yay! at last. took it up the road and bingo no flat spot no coughing and Christ does it shift now! only issue now is the 'close' cable is to short and all three sets have identical fittings,brackets etc and ive checked the twistgrip and alls ok that end so a bit confused . still minor stuff as i zip tied it safely to the bracket for now as i will modifiy a bracket to suit and refit to be safe. thanks for the help but i do now have some fzr400 slides with good diagrams(6) and 2 fzr600 ones so may be able to get some of the outlay back! cheers,del.

[pnbell]

Wow Cool! Great to hear it worked out.

*Not the first time i have heard someone just give up on a set of carbs and get other ones.