The FZS1000 carburation can be adjusted to run well in a bike with standard airbox/filter and standard exhaust or slipon (I’m using Akrapovic) without resorting to jet kits. This bike is set to run lean low down and rich up top - found after I had a fuelling check done by a respected dyno operator.To fix the lean issue I fitted one size larger pilot jets (#17.5) set Pilot screws to 3.1/4 turns out. It’s not ideal but the stock #15 pilot jets can be used with Pilot screws set to 4.3/4 turns out.Set float height to the standard 13mm which make fuel level the standard 3 to 4mm Standard needles in standard position 3rd groove from top with the std 3mm nylon needle spacers are fine. Fuelling air/fuel ratio is flat so needle tapers are about right.I’ve heard that some bikes have 2.5mm spacers? so these may need raising 0.5mm.Fit 2 size smaller main jets to fix rich top end Main Jets - 127.5 on the outsides cyls 1 and 4, 125 on inside cyls 2 and 3.That’s it.
After doing this mod for several years, I settled on enlarging just one of the three pilot bypass holes (the middle one) and set the mixture screws to 4 turns out.
Quote from: Falcon 269 on 11 February 2023, 06:05:08 pmAfter doing this mod for several years, I settled on enlarging just one of the three pilot bypass holes (the middle one) and set the mixture screws to 4 turns out.Thank you for your answer! May I ask why exactly you switched to drilling one hole and does this apply for the SO kit and MB kit?
Thank you so much for these incredibly detailed answers which are so helpful.Gaz66, so you are saying cleaning the carb ultrasonic is bad?I just bought another carb on eBay to be safe (and leave my current one untouched), it has been already cleaned ultrasonic by the seller. There are also Tourmax repair sets included. Can you see from the photo if they include everything I need?Photos:https://i.imgur.com/3PBMYMw.jpghttps://i.imgur.com/hpeg0Qe.jpghttps://i.imgur.com/cUHBJcy.jpgThe diaphragm seems not included. Would you recommend this:1. https://de.aliexpress.com/item/1005004439949836.htmlor 2. https://de.aliexpress.com/item/1005004511397054.htmlAlso, the seller of the carb also wants to sell me this "Long Boy extended Fuel Screw Set": http://www.factorypro.com/Prod_Pages/prody69.htmlWould you recommend that with the Ivan Kit or is it not needed?Hi Julius ... Think you've misunderstood what I meant re: Ultrasonic cleaning.I meant that if "Air cut diaphragms" are still installed during either solvent or Ultrasonic cleaning, the diaphragms may not survive any contact with solvent, Ultrasonic cleaning is very good in most instances, I use mine for all-sorts, but water/solvent can be trapped withing the diaphragms chamber, along with dirt etc, hence they ideally need to come out when carbs are washed out .... bit of a piss poor design by Mikuni imho but it's something I've come across over the yrs doing countless carb servicing jobs .... Yes I fully recommend buying a set of the diaphragms from Ali-express, if only as a spare set, should you discover yours are in poor condition when stripped, it's clear why they get overlooked, splitting carbs apart is a job often swerved due to it being a fiddly process, it's common sense to replace the fuel o-rings between each carb joint while they're apart, after all they all between 17-22yrs old.I've also found out by trail & error that "Holts EGR cleaner" is awesome at cleaning carbs (externally & internally) cleans brass jets a treat, even had pilot jets remain blocked after a few sessions on the Ultrasonic bath, I also keep a few single strand guitar strings as jet un-blockers, also handy to poke thru carb galleries to ensure nothings stuck fast... just don't let this stuff come in contact with any rubber, hence a full carb strip as mentioned in my previous reply.EGR cleaner is a good option if you don't have the use of an Ultrasonic bath.Extended fuel screw ... is an option, as OEM screws are very hard to get at & be accurate as to how many turns out you're at with carbs in situ on the bike, never seen any on a Gen 1, but I have considered them in the past, it's a pricey option for something that rarely needs to be adjusted after a carb rebuild.Ivans MB kit, is the way forward imho, it may be worth only drilling 1 bypass hole as Mike recommends, as I've drilled 2 & it's clearly too rich at idle & spits sooty deposits from the tailpipe, my white garage door looks like a paintball firing range from exhaust blast, note to self, "Clean the garage door ".
If you have a search around on the forum, you will find somewhere, dyno graph comparisons between both versions and a standard Gen1 as well iirc?
also no one ever mentions separating the carbs to inspect or replace the "Air cut valve" diaphragms, only 1 can be accessed with carbs together, 3 can't so they need to be split apart, seems it's an often neglected part on these Mikuni's, bike won't run correctly without them being in good order, plus you can't fully clean out the carbs effectively with either an ultra-sonic bath or solvents, Solvents will likely damage the diaphragms, I believe they're no longer available from Yamaha, plus they'd be silly money too ...
Quote from: Falcon 269 on 11 February 2023, 06:05:08 pmAfter doing this mod for several years, I settled on enlarging just one of the three pilot bypass holes (the middle one) and set the mixture screws to 4 turns out.You also shorten the springs 12mm instead of 19mm, right?
Btw, to remove the throttle cables I didn't stick the carb into manifold one but just leaned the seat against the bike and used it as a stand which was very comfortable.
Which leads me to refitting the carbs into the intake stubs. If you don't need a crowbar to get them out of the stubs, you don't need straps and levers and Lord knows what else to refit them. Nice one, Julius - good luck with the rest of your work and please let us know when it's up and running.