bad carb tune

[nazaaron]

^ awesome!!

yeah ill do some reading and post up a tune that works well for me

cheers guys!

[nazaaron]

so i found this thread while reading up on carb tuning

http://www.netrider.net.au/threads/fzr2 ... ng.135481/

the person mentions something about a needle being set to the second highest clip position. anyone know what hes talking about?

[yamaha_george]

NA,
he is talking about the carb needle attached to the the diaphram & slide. I have never seen an FZR 250 BUT I know Yamaha.
Some of their markets did not allow the owners to mess with carb settings for emission control . The needles in those were fixed . However else where the top of the needle had typically 5 grooves that allowed the needle to be raised or lowered with respect to the cone shape of the needle jet so that fuel metering could be altered slightly for any given throttle slide position.


Having said that the author you refer to leaves the meaning ambiguous :-
"2nd highest clip position"
He could mean the adjusting circlip is in the 2nd position from the top Which actually LOWERS the needle further down the needle jet.
OR
he means the needle is raised to the second highest position by puting the circlip in in the 4th slot from the top (assuming 5 slots in the needle.

If I was trying to sort this phase out I would put the circlip in the darn middle (3rd slot) run the bike.
Then put the circlip in the 4th from top run the bike and see if it feels better or worse and depending on that I would then put the circlip in slot 2.
I personally would do it that way round as the 4th position is richer normally than 2nd and a leaned out bike can be expensive a rich fueled bike will just burn more gas.

[nazaaron]

Gotcha George. Yeah nah i dont recall there being anything to adjust with the diaphram and needle. strange as that guy says hes got a fzr250 3ln that is fully stock..i was assuming it was the same, though one of his jets it different to mine also.

[yamaha_george]

NA,
You would have to take the cap off the carb and VERY carefully lift the diaphram & slide out and take a torch and peer down into the hollow of the slide. Down at the bottom will be a fixing that stops the needle from getting jammed up it may be just a simple washer that the spring seats on. once that washer is out the way the needle IF adjustable can be shook out and you can clearly see the grooves IF it is in fact from a market that allowed that mod .

[nazaaron]

hey George
yeah i found it haha i checked one and it was on the middle.. i havnt changed it so i think il leave it for now (ill open them all and check they all the same before i put it back in)

ok i just wanted to ask now i double checked the floats 2-3-4 were 14mm from the gasket (inside the float chamber) and 1 (the extreme left as you sit on the bike) that float height was 13mm ... would that make such a difference to effect the bike alot?

i set them all now to 14mm now.. i just wanna know if I should adjust them again (like to it 15mm or 12mm) before putting it back on the bike and testing it..

[yamaha_george]

NA,
Ok lets get something straightened out for the readers as a general comment.
ALL 4 carbs do NOT need to be identical they usually are BUT with manufacturing tolerances diff cylinders "breathe" differently.

Having got that out the way I would expect the float heights to be identical, what the float height is and how you measure it with a nifty DIY tool is given else where (WIKI) as to go 12 - 15 depends on how the engine runs rich or lean

For now i would check that all the needles are set the same all the jets are the same number (please note the discussion else where about jet numbering and "flow control" )

I hate to break the news to you although i guess you are learning " owning a bike is not just putting gas in it , the dash of oil and coolant and go ride into the sunset"

Everyone on this board has been there done that to some extent just take notes ask and hopefully some one will have an answer.
I am away for New years with Camala as it his her birthday tomorrow so will not be back till wednesday .
Till next year have a good New years you all.

[nazaaron]

gotcha George
i was reluctant to make and use the nifty tool but i guess il have do it

happy holidays everyone and have a happy new year

[Nik]

NA,
Ok lets get something straightened out for the readers as a general comment.
ALL 4 carbs do NOT need to be identical they usually are BUT with manufacturing tolerances diff cylinders "breathe" differently.

Having got that out the way I would expect the float heights to be identical, what the float height is and how you measure it with a nifty DIY tool is given else where (WIKI) as to go 12 - 15 depends on how the engine runs rich or lean

For now i would check that all the needles are set the same all the jets are the same number (please note the discussion else where about jet numbering and "flow control" )

I hate to break the news to you although i guess you are learning " owning a bike is not just putting gas in it , the dash of oil and coolant and go ride into the sunset"

Everyone on this board has been there done that to some extent just take notes ask and hopefully some one will have an answer.
I am away for New years with Camala as it his her birthday tomorrow so will not be back till wednesday .
Till next year have a good New years you all.

Y-G,
aint that the truth, I learned that from you 30 years ago and i am still trying to play catch up with you guys.

Camala see you at the Party monday evening

to the rest of you :- be well , ride safe and keep asking questions ......
Happy New year folks

[nazaaron]

happy New year everyone hope you all hada blast!

got my bike moving again.

float heights all 18mm
float levels around 10-12mm above the exterior carb line
bike still doesn't start without me giving it throttle i think the idle air screw is to high might need to go go from 3turns out to 2.5.. am i right??

also i think the bike is running rich.. the reason i say that is it bogs (like shudders) giving throttle under 9k while it picks up 9k+ with black smoke and backfires
in neutral 1/4 throttle slowly up the revs at 3k gave it a 3/4 throttle.. bogged nd increased.. did the same al the way up to 10k revss..

took it for a road test.. it performed the same as i just explained with the bogging and picked up higher revs..

not sure where to go from here

[GreyImport]

Checkout the exup valve....

http://www.cartestsoftware.com/fz1/exupmaintenance.html

http://www.yamaha-motor.ca/technology/t ... M&tech=EUP

Are the correct spark leads from the coils going tp the correct cylinders?
1 coil sparks 1 and 4 cylinder and the other 2 and 3.

Have u checked the intake manifold rubbers for cracks/splits?

[nazaaron]

hey GI

i did check the manifolds rubbers.. they were split and were slightly restricting air flow into the engine.. i shaved the edges on the inside.. do u reckon i need to buy new ones?

the leads are correct.. ill check them again.. check the spark plugs again to..

im doing the exup today.. let u know how that goes

about the floats.. i see that u have a 3ln aswell any idea what your float heights and levels are?
people say the levels got to be 10mm above the line of the carb.. i just cannot get it that low.. there is this needle with a spring action button, that the floats close when the chamber is full of gas... adjusting the floats heights (18mm right now) the flange is bent in a way that the button doesnt fully close right now.

[GreyImport]

Hey mate
Depends I guess how badly split they are.....I actually checked mine yesterday as I hadnt removed them yet (and your post reminded me! ) and there was alot of crazing and cracking which u ony see when u "bend" them about,especially at the "joints" of the moulding.....I couldnt find any that went thru to the inside but Im going to eventually replace them.......the problem there is they are hard to find and not cheap as (I think) they are pretty much model specific.
Heres some I found on ebay....I would snap these up but the budget wont allow it at the moment as Im trying to get the bike on the road very soon.
They are cylinder specific and are marked 1-4 so they are an individual item.
This seller has all 4 and would probably do a "deal" on buying the set.

http://www.ebay.com.au/itm/330775173330 ... 1423.l2649

I havnt done anything with my carbys yet so I havnt investigated the float level scenario.....from what Ive read so far (from memory) everyone has a different tale.....
The bike ran ok before I pulled it down so im just going to put the carbs back on and see how they go (I need to get it mobile for rego soon ).....also the PO told me the "carbys had been done"...

With the spark leads have u checked the actual wire inside ?...... I unscrewed the caps and cut about 5mm off the ends.....which let me see the condition of the multicore and gave the cap some new stuff to screw into.

Also have u changed the inline fuel filter? ......and there are filters inside the tank.....is your tank clean? ...fuel lines ok?
This is mine...and there was a ton of junk and loose rust inside.

[DonTZ125]

Nazaaron - if the operation of the float needles is impaired, this could very likely be the cause of the latest too-rich running.

To the best of my knowledge, no-one has a good number for the float height or fuel level for a 3LN. The 10mm fuel level is IIRC for the 2KR.

[nazaaron]

hey don.. yeah exactly the 3lns are so awesomly rare they dont have a manual haha its so hard to try and incorporate the 2kr and the 400s manuals to the 3ln..
but yup ill try tuning the floats some more

doing the exup right now.. the links GI posted are a real help THANKS.. the hole doesnt line up even after turning the key on and off.. so il sort that out now and do the floats after that