Carb float height

[mars696]

I took out my carbs yesterday,to adjust the float heights,because of a long time idle-3k rpm stutter.
I find it realy hard to adjust them with the clear hose method...
I adjust them(at least i thought) and put carbs back in.......and guess what.....The bike runs like *@$#$@
It didnt improve the low stutter,and now the engine refuse to go over 6-7 rpm with load.....
I have done everything 9-10 months i am searching for the problem,EVERYTHING i have read here:plugs, plugs caps,carb cleaning,testing coils,tps and much more...
I am so sick of this....

[Punkstig]

Any cracks in the inlet rubbers, or any connections that coud be letting air in, including the inlet rubber caps where you connect to fit scottoiler/ fit gauges for carbs?
You've checked loads of stuff, what about the idle screws? They affect low down revs, not saying it is them, but as you've checked pretty much everything else!?

[mars696]

No air leaks ta all,carb inlets are new.
Pilot screw adjusted,by ear and even with cylinder tacho but nothing change.
Carb cleaned 3 times.They are in mint condition now..except one pilot screw i manage to snap...
The only thing i havent adjust was the float heights....and maybe i souldnt....
Plugs and plugs caps replaced,first and secong coil resitance checked,tps resistance checked.
K&n air filter super clean and oiled.Carbs synced.....and everything i read that might cause the problem.....
Now i have one extra problem to solve.....
I am thinking of buying some spare carbs....
Two mechanics have check my bike,without solution..

[Punkstig]

Where are you located?
Is there anyone on here willing to spend a few hours with you swapping over carbs from their own bike to see if that is 100% the issue before you go off buying a new set!?

[unfazed]

No air leaks ta all,carb inlets are new.
Pilot screw adjusted,by ear and even with cylinder tacho but nothing change.
Carb cleaned 3 times.They are in mint condition now..except one pilot screw i manage to snap...
The only thing i havent adjust was the float heights....and maybe i souldnt....
Plugs and plugs caps replaced,first and secong coil resitance checked,tps resistance checked.
K&n air filter super clean and oiled.Carbs synced.....and everything i read that might cause the problem.....
Now i have one extra problem to solve.....
I am thinking of buying some spare carbs....
Two mechanics have check my bike,without solution..

You cannot adjust the air screws by ear. It can only be adjusted by a CO meter pluged into the bolt holes in the downpipes.
I would advise you to set them all to 2 turns out.
 A common problem I have come accross is people setting the Pilot screws wrong.
The confusion stems from the fact that all the Box Eye models are 2 turns out and the Fox Eye models are 2.5 turns out.
A reason I have come accross for running badly to 3k is sticking choke plungers or cracked plunger rubbers.
Ensure the choke bar is moving freely and all the plungers are returning fully.
I have never seen a float height change with out somebody doing it accidently when cleaning the carbs
The rubber caps on the vacuum take off points can crack through much quicker than the intake rubbers ever will and should be checked regularily.
I presume you have checked the valve clearance ?
 

[reillypadraig]

This may or may not help, but I went trough 2 sets of carbs and ended up paying a fortune to some bollox to dyno jet one set and get it running properly on a dyno, he didn't, just got new carbs, still ran like shit cause of the after market exhaust because carbs came of standard bike, I just removed air filter altogether and it runs great, I know it's not for every one but I removed carbs and cleaned and put back in and adjusted this and that and lifted and dropped needles,

Best advise, mix screws as far as I could see only adjust the idle and up to 3k after that they don't count at all, it's the needles next, dropping the circlip down will increase trottle response and for me it cleared the bogging down, found 1 of the diaphrams was cracked , best way to find out is run an air line through the vent holes and if they all lift evenly then there fine.

Float heights can be done with carbs off, hold carbs at an angle so that the needle at the back is bearly touching and measure 14mm from base to top of float( I can be corrected on that!

Found it easy to do this with a barcode I ripped of a cardboard box,

Try find any leaks either side of carbs, if none then try it and see how it goes but float height isn't always the prob,

If you know anyone close that could lend a set of carbs it's a quick way to find out if your carbs are ready for the bin.



Not word of god but just how I got though it

[mars696]

Hi,thanks for the replies guys.
Reilly are you sure that the float height with the old fashion measure way is 14mm??Because i search all the web and i didnt find anything,only the clear hose way and measurement.
Unfortunately i dont know anyone with the same bike to check with his carbs...

[reillypadraig]

From what I can remember yes it is 14mm, but it's a small problem at idle that this effects, at high rev the vacuum from the cylinders means the fuel in each bowl doesn't get to fill up until u back of the trottle the the bowl fills and only uses what the vacuum demands, as soon a you blast the trottle again it stays around half - 3/4 full because the fuel is constantly going in and out,

I would worry about more important issues with the bike before messing with float height as the main cause

[mars696]

I took out carbs again yesterday and i adjust the float height with the clear hose way.
My God what a pita...
Fortunately the bike come back again,the 5-6k red line solved, [size=78%]but the low end it still there.[/size]

[Craiginuk]

Def Sounds like pilot circuit. I think there are some fine passages under butterflies that get blocked up. Mine is doing the same and i plan to take carbs off to clean when i have a chance.

[unfazed]

Always ensure if using air under pressure to clear the passageways and jets that you blow in the opposite direction to which they work. Blowing them out in the wrong direction can push the dirt further in and prove almost impossible to clear

[keirravn]

Another vote for the airfilter being the cause. Easy to identify just try a run with it out, if its ok replace it with a k and n.

I had an issue with mine when I bought it, it would bog down and stutter at full throttle from around 6 to 8k. I changed the plugs and fuel filter, cleaned and balanced the carbs, and trimmed the ht leads which stopped the stutter but it still bogged down, removed the airfilter and it ran perfect, and still does with a k and n.

When I bought the Bike the air filter had been replaced, but it was some cheap paper element eBay jobbie.