I am having a go at making carb. needles for an XV535, need to know taper dimentions for 5DZ9 and 5DZ10 needles thanks.

Only of you have ran the engine out of oil...Sounds like the carbs may not be set correctly.. .Did a professional do the rebuild?..What exactly was "rebuilt".. were any parts replaced?
Sounds like the low speed (pilot jets/air screw passages may not be clean as they need to be??)
Please check the compression on each cylinder..remove the spark plugs... hold the throttle (carbs) wide open when you check this.. spin the motor for 5-8 seconds... you should get 120psi. minimum..(and less than 10psi difference).. if less, it might be time to actually rebuild the top end..(new pistons/rings/hone cyl.).. only bore it if absolutely necessary.. get it measured..

There are only 3 parts in a two-cycle carb that ever need to be replaced,,(unless they are actually broken) The needle and seat assy., the jet needle and the needle jet. ..see pic... parts # 41 = needle and seat assy. #6 = jet needle, #37 = needle jet.



The needle and seat regulate the flow of gas into the carb as the floats rise and fall..,, if they are damaged or leaking the carb will overflow with gas., the needle jet is a orifice with a specific size..The jet needle has a specific size, taper, and length..== The jet needle and needle jet work in unison to regulate the flow of gas from right off idle all the way to WFO..the needle jet/jet needle WILL wear over time causing the fuel/air mixture to become richer and richer and start fouling spark plugs..(this is more pronounced on 4-cycle ATV's)...
I hope this has shed some light on your carb situation...
Good luck...
exploded view of mikuni carb Google Search

usually means you have to replace the carb and get the gasket with it. when the needle valve develops a problem they don't intend for you to fix it. this has been my experience.

Hi Shannon:
Possibles:
- Needle valve has been compromised, possibly held open with grit.
Carefully dismantle and blow out all orifices with compressed air.
- Float level set too high. Review the way the float shutoff mechanism works. Make sure the float moves up and down easily and that it still floats as intended. Double check the lever that moves the needle valve. Make sure it is correctly connected to the needle.
Reply as a COMMENT to this post to let me know what you find.
Cheers.

Pull lines from tank making sure where each goes to carb. Rinse tank out with carb. Cleaner then blow out with compressed air. Cut hoses to proper length as old ones but allow 1 extra inch. With this inch cut with scissors making a tapered end, drop oil on holes in tank to lube as you thread line into holes twist and turn hose into tank until you can get to ends of hose with needle nose pliers and then pull hose until you can cut of taper and install fuel filter in correct hose.

Buy new carburator or have it repaired by a carburator specialist. Had the same problem

Hi and welcome to FixYa, I am Kelly.


You can fix this yourself.
(Turn off the fuel selector)
Remove the carb float bowl nut and bowl. Note the gaskets upper and lower. Remove the float pin retaining the float and drop the float and float needle together.
Briefly turn on the fuel selector and then back off. You are flushing debris from the float needle seat. It is a good idea to use carb cleaner to ensure that the float needle seat area is clean.
ALSO spray carb cleaner into the threaded area where the bowl nut attaches. Your cleaning off the metering jet orifice up inside the threaded area.
INSPECT the float needle itself. The rubber tip should be tapered and pliable. If there are any nicks cuts or debris on the end of the needle first wipe it off and determine if you need a replacement float needle.

Reinstall float and needle ensuring you have the float pin properly installed.
CLEAN the bowl NUT along with the float bowl. Then reinstall the the float bowl. 2 gaskets upper and lower must be properly seated.

Turn on the fuel selector...
Test for leaks.

This should fix the leak but... if you still have the problem and did not change the float needle and seat. Change them. The float needle seat can be difficult to remove. I find that air in the fuel supply manifold fitting will blast most of them out but... sometimes I have to use a drill bit the size of the hole to cut the rubber material and then dig it out with a scribe or jewelers screwdriver. Just make sure to clean the hole with carb cleaner before installing the new seat. To install the new seat... reverse the drill bit using the flat chuck driven end and press it into place. Works great!

Thanks for choosing FixYa,
Kelly

The slides are the bits inside the carbs that "slide" up and down when you work the throttle. The needle hangs in the centre of the slide on a clip, the needle will have about 5 grooves machined in it, The needle is small about 3mm in diameter and it is tapered towards the bottom. if you move the clip one groove down, the needle will sit higher and let more fuel through and visa versa. to get to these you have to unscew the tops of the carbs, its a little hard to explain the whole process by writing it down and there will be some small parts to fly off and lose, please make sure the throttle snaps back to idle properly before you test ride it

get yourself a set of cheap calipers from autozone to figure it out for sure, be aware that by changing the filters, you might need to change the carb jets to accomodate the different amount of airflow that you will expierence. Ussually it will take a two step larger jet then what was on it, but not always.

Yes.

1.Remove the Float Bowl, (Turn gas off first), and clean the crud out of the bowl. (Bottom of the carburetor)
There is a brass nut in the middle of the float bowl, which is on the bottom of the carburetor.
There is a fiber, or brass washer on that bolt. DON'T lose it! (Turn it to the left)
The brass bolt, (Main Jet Plug), goes through the float bowl, and into the Main Jet.

Remove the float, (Carefully! If it's a plastic designed float, Don't nick it with your fingernail/s. Also make sure it isn't soaking up gas. If so, {You'll know!}, replace it)

A.DON'T let the float needle valve fall out, when you remove the float! The Float Needle is attached to the float, with a small 'hair spring' clip.

B.DON'T lose the tiny, 'hair spring' clip, that attaches the float needle to the float.
Observe VERY carefully how this tiny spring clip goes on the float, ->Before you remove the float pin. (The float rotates up, and down, on this long round pin) It has to be put back the same exact way)

Handle the float with extreme care. It is set to a certain height. The measurement goes from the bottom of the carburetor body, (Where the side of the float bowl touches), to the top edge of the float.

The top of the Float Needle has a groove cut around it. That 'Hair Spring' clip I described above, clips in this groove. The other end of this 'Hair Clip', goes around a flat area that extends out of the side of the float.
Once you get the float bowl down a bit, you'll see what I'm referring to above.

C.The Float Needle Valve is made of metal, and has a Neoprene, (Like rubber), tip on the end. The Neoprene tip is cone shaped. A light little ring mark on the Neoprene tip is okay.
If the tip is broken, or mushed out, the Float Needle Valve is no good.

More than likely you just have crud in the float bowl, and it is also down in the Float Needle Valve Seat.
(The Float Needle Seat is a brass cylindrical shaped piece. It has a tapered hole inside, down at the bottom. Fuel, {Gas} comes through this tapered hole, and the Float Needle Valve regulates how much. The float raises, which raises the float needle valve. Fuel comes through the tapered hole. The float drops, which lowers the float needle valve, and stops fuel from coming through the tapered hole, and into the float bowl)

After time, the bottom of your gas tank develops rust, from moisture in the gasoline.
Dirt also finds it's way into a bike's gas tank. Also the additives in gasoline accumulate after a while.

If you do not have an inline fuel filter, I advise you buy, and install one. This way you change the fuel filter element, and do not have to tear the carb/s down again.