bad carb tune

[nazaaron]

ok exup checked and adjusted.. took it for a ride.. felt the difference actually but still theres that delay at low revs under 8-9k.. still back fires at higher rpm

gonna try and get those floats sorted now!

[nazaaron]

hey every1.. so i did the floats but am still not 100% happy

float heights 15mm from the gasket (at 45 degrees as to not push down on the button thing)
float levels 13mm above the line
needle clip position in the middle (haven't changed)
idle air screw still 3 turns out
exup cleaned and adjusted to line up to the hole
spark plugs cleaned and are good i guess (because they weren't that dirty/oily) (gave it a light sanding between the gap)

bike runs good but still not awesomely awesome

in neutral, stationary and warmed up, full throttle the bike lags at first then increases. this happens through out rev range but more down around 8k rpm.
now i read somewhere, either here or fzr250 forum called 'carb tuning' or something.. someone wrote symptoms and what to do about it step by step
if you know what im talking about please LINK ME! i cant find it!
anyway in that, that person talks about this symptom and to adjust the needle clip position.. is he right? if he is which direction should I adjust it to (up-down is confusing as i don't know which way he looks at the needle)

to add: after a high rpm run i could smell burnt gas.. may be to rich still?

to add again: i haven't synced/ balanced the carbs im just reading up on that now

[DonTZ125]

Factory Pro CV Carb Tuning Procedures

[GreyImport]

Sounds like youre getting there.......

Balance the carbs and see if that helps...which it should.

http://fzr250.com/viewtopic.php?f=20&t=1702

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

I know wat u mean about not finding some info again....I try to save everything I see will be useful and even then I cant find things!

[nazaaron]

hey thanks for the links guys!! really saved me time and helped me out!

ok so did the carb sync.. not a professional sync because i didnt have vacuum gauges.. so i did it how one of the 600 boys did it on the wiki with the guitar string and feel!

wasnt too much of a difference.. i guess my carbs were pretty synced already but anyway i did it.. so i know its synced now, thats another tick of the list

*sigh* problems still there ...

is it normal and am i making a big deal out of nothing???!? its when the revs are high and dropping as u let the throttle close.. then full throttle at around 8k rpm.. lagggg then increases??.. im gonna go take it for a ride and see if its bad while riding..

thoughts anyone!?

[sylvaner01]

G'day buddy, http://www.netrider.net.au/threads/fzr2 ... ng.135481/ is actually my thread haha
I am having similar issues with my bike, here is a link to my thread: http://fzr250.com/viewtopic.php?f=2&t=3 ... 242#p29242

Are you sure the boots which connect the carbies to the head are not cracked? if they are you might be able to get away with coating them with a layer of silicone depending on how badly they are cracked.
Check that the airbox is fitted to the carbies nice and snug, I put a bead of silicone acound each intake point just to be sure NO air was leaking in.
When you did your balancing of the carbs make sure those holes are plugged up well because any air leaking in there will mess with your setting heaps.

Make sure your valve clearance is up to date. It looks hard but it is pretty damn easy to check, I knew nothing about motorbikes a few months ago and even I find the job pretty simple.

Just read how you did your carb sync, never mind what I said before, I would invest in one of these babies : http://www.ebay.com.au/itm/MOTION-PRO-M ... 20c993f83e
it is a one off cost and you can save so much time and hassle.
I brought one of these after attempting to sync using the diy methods and it was so much easier and more accurate.

Anyway, I lowered my fuel level to about 5mm above the line on the carby body and that seems to work pretty well, I might need to do some adjusting to get it to perfecto but if I find the best settings I'll let you know.
Also, one thing I checked today is that my valves on the floats were stopping the flow of fuel without any leaks.
I did this by taking out the carbies and hooking a hose to the fuel inlet. I took the carby float covers off so I could see the floats in action. I then turned the hose on very low and and moved the carby so the valves were stopping the flow of water. If your valves do not stop the flow of water you need new valves.

I'll keep you updated on my progress mate.

[nazaaron]

hey S01 yeah fine tuning these bikes takes sooo long if your noob like me haha

when you checked your float levels was your bike on or was just the battery on? (wondering if that makes a difference) cuz i cant get my levels THAT low with just the battery on.. im about 12-13mm above the line where im pretty sure the needle button that the floats close..is closed. at about 15mm float height.

[sylvaner01]

Hey mate mine pretty much was closed when I set the float heights haha but seems to be working alright.. I'll play around with my air/fuel rAtio when I get some more spare time and I will give you every spec I have and also hopefully make a sticky on all fzr250 websites so other people don't have to start from scratch! Try lowering the fuel level as far as you can, I checked the fuel level on the outside of the carb body by just filling the fuel intake point with water until the carb was full. Make sure the carby is at the same angle as it would be on the bike. Yes this method is a royal pain in the ass but it must be done!

[DonTZ125]

Bear in mind that publicizing a fuel height based on water won't be accurate for most riders, who will be measuring using fuel. Could you remeasure with the carbs installed and hooked up,the key on and the engine off?

[sylvaner01]

I was unaware it makes a difference, point taken. If I get a chance to remeasure I will write it down.

[nazaaron]

hey guys check this video out

http://www.youtube.com/watch?v=aRXkZNkW5i4

this is my bike.. and this video explains better than words what my problem is..
is this normal for fzr250s?
if not normal, can this lag/delay in revs be tuned out?
if it can, how can i tune it out?

it happens throughout rev range but focused on around 9k, yes the bike is warmed up as i just finished a ride.. and i am going from no throttle to full throttle.

[nazaaron]

can anyone confirm this with their fzr250 or even any other carbureted 250 around the 1990s

also there is alot of knocking sound around the engine.. will a valve clearance and adjustment sort that out?

[sylvaner01]

Solved my issues http://www.fzr250.com/viewtopic.php?f=2&t=3940 do a valve clearance check buddy, you might find your valves are way out.