flat spot at 5-6 thou rpm

[biker bob 12]

I have removed carb 3 times adjusting floats cleaning jets-still the bike flat spots at 5 to 6 thou rpms-if i hold the throttle a bit it will go to max rpms then go past to 7 or 8 or more rpms-carbs are very near syn-tested fuel pump--passed--coil has a crack but not showing a problem--what is wrong.

[Johnj]

Have you tried raising the needle?

[totalmotorcycle]

Are you jets and needles old or original? If Johnj's idea doesn't work then it is most likely they are just worn out after 30 years. (1984 honda v30 magna right?). K&N should have a jet kit replacement for them all. I had to replace all mine on my 1982 Yamaha Seca but after that it ran really strong again.

Mike

[biker bob 12]

Have you tried raising the needle?

How do you raise them? Are you saying the sliders are not lifting the needles enough?
The bike is old but has 18000---can the needles wear out that soon?
I looked into carb kit and the front kit is different than the rear kit--I see no difference--main jets have same # so do slow jets have same #--only difference I could see was the main jet holder has a different hole pattern but look the same size--could I have them mixed up?
I bought a complete carb set (still in the rack with air box) have used all four sliders with needles from the used e-bay carbs also used all four butterflys because they looked better than mine--the bike ran the same as it is now before I swiched parts which caused me to start looking elsewhere for the cause of the hangup in rpm's.
It makes sence--what you are saying--and explains why if when I reach the flat (like it is starving for fuel) and hold the throttle steady then slowly increase it will sometimes get past the stumble and tac out normally---like the sliders are sticking some-as I recall now if I start out with full throttle through all gears (full throttle) it don't stumble--tacks out normally but I am going way to fast now--70mph plus. The longer I stay with this idea the more I remember--when I had the carbs off for cleaning etc. I noticed some sliders would return to seat faster than others when I would move them by hand up and down. A couple would stick open and not close at all so I removed them and re-clean the bore and slider body and then they would close better but not snap shut as some did---some close faster than others. Looks like we are at the heart of the problem here--I am thinking all the sliders should move up and down when moved by hand smartly with no drag--am I right? If so off come the carbs again--can I use say some very fine sandpaper (2000) and buff the bore some and mabe the slider it's self with out harm? Or what kind of cleaner should be used? I cleaned them with gas (slider so as not to harm diaphram) and carb cleaner on bore.
Also having a problem setting idle after warmup--first it's to high then it's too low--may be related to sticky sliders??? YES
Thank you John for your help---and more to come I hope---I am not going to do any thing till I hear what you think about all this.

[Johnj]

The needle is held to the slider with a clip, and there should be several notches on the needle for the clip. The clip should be in the same notch on all four needles. I would try lowering the clip (raise the needle) one notch.

It also sounds like all four of the slides need to be "fit". All the sliders should slide without restriction and snap shut. You are on the right track.

[biker bob 12]

The needle is held to the slider with a clip, and there should be several notches on the needle for the clip. The clip should be in the same notch on all four needles. I would try lowering the clip (raise the needle) one notch.

It also sounds like all four of the slides need to be "fit". All the sliders should slide without restriction and snap shut. You are on the right track.

Ok I understand what you are saying now but my needles have no notches--it is just a needle that looks a lot like a tapered nail--no notches--I could put a washer (small) on the needle shaft that would in effect raise the needle the thickness of the washer??--what I am going to do is remove gas tank and air filter box then I can access the sliders with out having to remove the carbs--buff out the bores with wet and dry 2000 grit and clean them till I get what you describe "fit" and the slides snap shut with out restriction.

Thank you for the help John---bob here will post results when done.

[biker bob 12]

Are you jets and needles old or original? If Johnj's idea doesn't work then it is most likely they are just worn out after 30 years. (1984 honda v30 magna right?). K&N should have a jet kit replacement for them all. I had to replace all mine on my 1982 Yamaha Seca but after that it ran really strong again.

Mike

Thank you Mike for your help--as you may have noticed I have been working with Jhon and I think we have the problem nailed--I would have and still might go the kit rout but as you know they are $50 each =another $200 my bike has been stored for over 5 years in previous owners garage an has only 18000 on it--1984 honda vf500c v30 magna.
Just in passing do you know what the difference is between the two front carbs (down draft) and the two rear carbs (side draft) are??? The main jets and slow jets are same number's and the slider needles are all the same number stamped on them--when you go to order the kits (canada)they say the kits are for front carbs and a different kit for the rear carbs-They are temp out or rear carb kits---Ill be damed if I can see a difference--I called them asking this question and the say the needles are different but I took all four sliders apart and the needles all have 2ve stamped on them?????? I was thinking I may have mixed the parts up??? The manuel also says the carbs are not the same (not telling me the diff Clymer again) Save that the front carbs are down draft and the rear are side draft--I never took the carbs out of the rack (air box) so they are in the correct position with each other

[Johnj]

Down draft means the flow of air through the carb is in a downward direction. You might want to read this.

[HYPERR]

Ok I understand what you are saying now but my needles have no notches--it is just a needle that looks a lot like a tapered nail--no notches--

You have a stock needle. The aftermarket ones have notches and collars so you can raise it.

[biker bob 12]

Ok I understand what you are saying now but my needles have no notches--it is just a needle that looks a lot like a tapered nail--no notches--

You have a stock needle. The aftermarket ones have notches and collars so you can raise it.

Ok--mabe I should just get aftermarked needles--does the needle height affect the idle? Right now my idle is erratic.