Mixture and Balance

[MarkT]

Hi well I've done about 1500 miles on my fzr now and still love it!! I have never done the carbs but know seems the time. When I first fitted them I put the gauges on them more to check for a good vacuum on all four, but just wanted to ride it so I left them alone!! Now the idle really is getting ragged and when riding speeds JUST above idle it can shudder along until I give it more throttle or change gear. You know my bike now no exup, straight through exhaust etc.
One thing it does do now is when closing the throttle to revs nearly die out then come back up to idle (1500 I have found best). If I remember from my 2 stroke days is the sign of weak mixture so need to possibly set that also.
There has always been a slight flat spot just off idle but I am not expecting this to be perfect with no exup!
No idea what mixture screws are set at but ought to check em by counting the no of turns in

Quite happy doing the balancing which is bound to improve things, but if the revs still drop then come back up I guess I will have to richen mixture!

I was thinking then to put screws at standard 2 1/2 turns out and then screw them in a half at the time until ok?

Any tips or help would be great especially if I'm thinking along the right lines?

Thanks all

[Hogdigerdy Dog]

sounds to me like your getting the measure of the beast

i'd leave the air screws at standard and balance the carbs, you can't really get the mixture right until all the carbs are in tune
mine was running like a bag of sh*t much the same as yours, tickover all over the place but once the carbs were balanced it was like a new bike, it really does make a lot of difference and not just at tickover, right through the rev range it is much crisper and more responsive once the carbs are balanced

get a bottle or something for a mini fuel tank (i use an old lawnmower petrol tank) as you cant balance the carbs with the tank on, it's a right pig reaching the screw with it off

[MarkT]

Thanks for that, just come in from another great ride! I bought a bottle and hose Inc tap from a dealer a few years ago so that's the supply of fuel sorted. (never used it still in bag) I wanted to basically make sure the bike was ok after fitting carbs and it came to life at last. Got forks to change and balance carbs this weekend and I can put fairings back on at last!! After all these years of biking I just love the fzr and still grin whenever I ride it. Thanks for advice!

[MarkT]

How the he'll do you get to the balance screws ? I have spent all morning trying to find no one with torch and mirrors but just can't seem to find them round the back no matter what! I even took air filter off my just ended up burning my hands to bits and loosing a bleed screw washer! They are not madly out but no one is a bit low and could do with a tweak!!
I hate being beat so I have just left it hoping to get some help from here!

Thanks

[Hogdigerdy Dog]

you cant balance the carbs with the tank on, it's a right pig reaching the screw with it off

there's 3 one between number 1 & 2/ one between 2 & 3 / and one between 3 & 4
whip the carbs off and have a look for em, then when you've found em put the carbs back on
it's easier to locate em if you can visualize them, as you can't exactly see em with the carbs and air box on
don't forget just the pressure of the screw driver will change the setting so it's a question of a little tweek then remove the screw driver and see and so on
do 1&2 then 3&4 then balance together with 2&3

[MarkT]

Thanks yes I have a spare set of carbs to see the screws but no matter how I tried I could not get a screwdriver on it! Idle bracket also gets in the way.

[MarkT]

I think I need a special angled screwdriver to make the adjustment? Any idea where I can get one?
Mark

[Hogdigerdy Dog]

don't know that an angled one will help
i used an inspection mirror (dentist's mirror) a bit of light and a lot of patience
it is doable, but as i said earlier a right pig,

EDIT: just been through the pics of my bike and would you believe i don't have any of the carbs (which is strange as i usually take pics of any jobs i do)
could you post a pick of the spare set of carbs and point out the screws, just so we know were on the same page of the hymn book

ok found one on the bay it's the 3 screws between each carb,
level with the center of the butterflies
with the springs on as they adjust both ways, in does one carb out does the other
http://www.ebay.co.uk/itm/YAMAHA-FZR-40 ... 2eb81ccb47

[MarkT]

Thanks very much yes that's the screws! a mirror like you said would be ideal! Using the wife's compact mirror at the mo!! But it's too big really. Only no1 really needs doing but the idle bracket and exup motor is in the way! Have another go tomorrow. I think the mixture screws need a tweak too as when you rev a bit the tickover dies down to 1k then comes back up, and I set idle to about 1.5 to 1.7k to stop it stalling. Without carbs being in balance can't do anything else but I might just put up with the dipping idle.
Thanks for posting
Mark

[Hogdigerdy Dog]

you cant just balance 1 carb

as i said the screw works both ways, as it's attached to 2 carbs then through a link to the other 2
to bring no 1 into balance with no 2, your actually adjusting both, one out a bit and one in a bit, or visa versa
once you've done this,
it will throw out the balance between no 1 & 2 AND no 3 & 4 so you'll need to adjust the center screw as well to bring all 4 together again