bad carb tune

[nazaaron]

hey everyone hope you all having a good Christmas!

so i got a problem with my bike.. most probably a carb issue..
i got a fzr250r 3ln1 1989 with the bdst28 carb
checked out this forum for weeks finding out what all you guys have done to your bikes and i decided to have a go myself.
took the carbs out to give it a clean and did some adjustments here and there.
the bike was running well (really well before i did the adjustment) but now its all gone to shit.........

ok current settings
idle air screw set to 3turn out from the bottom
float heights (as in in the float chamber) is 13mm from the gasket
havn't changed the jets or anything they are all factory.
.. thats basically all i changed.. i dont know what it was originally as i didnt think at the time to measure it before i changed it.

symptoms are
1. the bike doesnt start so nice.. i have to put the choke on full, press the starter button and give it a little throttle and then it starts (cold starts) when the bikes warm no choke but still needs throttle to start. this could be because in order to take the carbs out u have to disconnect the throttle cable so may be i changed that in a bad way when putting it back.

2.the bike has gotten sooo sluggish under 12k rpm... i used to have power from 6k upwards

3. the idle seems like not enough fuel is going in (actually while i ride the whole time i feel there is not enough fuel going into the engine) feels like its gonna die at anytime

ok thats it i think.. please let me know if anyone here has any advice..

cheers - Aaron

[reelrazor]

hmmm running really well 'before'

and

not so much now.

Get back in theer and put it back the way it was. Be very very careful and take your time pulling things apart and mayeb you will catch where you made your mistake(s).

[GreyImport]

Go back and retrace everything u disconnected or moved about.....like cables and lines etc....make sure the choke is set up properly.

If u have been fiddling with the carb settings they may need to be balanced/synced again

[KaspenOne]

yes double check the float hight, afther that check your air screws try 2.5 then 3, then 3.5 , sync your carbs, and make sure all cabels are adjusted properly. if you hav the bog feeling when you give it gas and then all of a sudden it picks up on top end then its going to be a fuel and air mixture adjustment needed, at least that is where i would start. pull your plugs inspect, if they are wet you are running to must gas and its not burning, drowning the engine...

[yamaha_george]

Hi,
Sorry to hear of your problem, BUT I keep hammering this point when you buy a bike BUY A NOTEBOOK for it.
When you work on the bike every measurement is to be noted as you FIND it that way if you inadvertantly alter some thing you can set it back because you wrote the original settings down.

Just because you are John Q Public does not mean you cannot copy the pro-racing team mechanics.
I learned from one visit with one of the best tuners of the day Kel Curruthers (tuner for King Kenny Roberts & the yamaha race team)
Used the "system" on every job i have done since, which is probably why i was offered the franchise and manage yamaha service after only one year in my own business as a bike fettler

[nazaaron]

yeah your totally right George.. i started doing that a little late and wrote only my settings down, instead of how I got it.. but i learned my lesson now haha

can you help me understand that idle air screw.. its at 3 turns out now, i remember it was around 2 and a bit when i got it.. does that make it lean or richer than 3 turns?? with it being more richer it would idle higher??

and also my thinking for the float heights inside the chamber, is that when the carbs are on the bike the higher the floats stop means the more fuel is inside the chamber which means it would have access to more fuel throughout the rev range?? so its at 13mm from the gasket right now the higher the mm the better?? whats a good margin to go up or down by? .5?

[yamaha_george]

N,
I am VERY rusty with FZR settings (not been on the bike or even near it for nearly 2 years ) the float height is critical and in the WIKI I believe that Rage did a piece on float heights& how they alter performance.

Please note float height varies model to model so check the OFFICIAL manual for your Model

As to air screw mixture the RPM will pick up ONLY when the mixture is damn near right. Lean or rich will slow the RPM VERY subtley best to use a stethascope at that time(mind you that may have been age on my part)

[GreyImport]

http://fzr250.com/viewtopic.php?f=31&t=3508

http://fzr250.com/viewtopic.php?f=20&t=1487

http://fzr250.com/viewtopic.php?f=20&t=3451

[yamaha_george]

Hey GI,
that is a great set of links I gotta love the carb stand & fuel level tester pure ingenuity.
Thanks gonna add them to the WIKI

[nazaaron]

dam this sucks i cant view the links.. nor can i sign up to that site.. is there any work around to view those links??

[GreyImport]

To register......

FZR250.com
The Premium FZR250 website! For Registration, or any access problems please email Dave at fzr250.com

Forum is very quiet these days but it has lotsa great info and the occasional poster passes thru....

Try the links via the wiki....

http://fzronline.com/wiki/doku.php?id=t ... _book_list

under "very useful sites"

[nazaaron]

hey thanks GI

the thing is i tried the very useful links and it still comes up to the sign in..

Dave@fzr .. sorry im really slow.. got it thanks

[KaspenOne]

let us know how it works out and what you did

[yamaha_george]

NA,
yeh the first link took me to a sign in too but i closed the browser and then clicked the 2nd link & 3rd link they both work fine for me here in the UK (the web site is hosted& run in Oz )


I have dropped the registered owner of the site & Dave an email asking permission to archive the pages both at Saltmine & here, BUT being holiday season and summer time there in Oz may be new years before we get permission to re-post .

[DonTZ125]

Y_G,

I'm one of the mods on FZR250. Dave is a very pleasant and reasonable fellow, and I have no doubt that he'll give his blessings. If you want, go ahead on my say-so and upload the stuff to the Wiki here.